US20030048746A1 - Metropolitan area local access service system - Google Patents
Metropolitan area local access service system Download PDFInfo
- Publication number
- US20030048746A1 US20030048746A1 US09/975,474 US97547401A US2003048746A1 US 20030048746 A1 US20030048746 A1 US 20030048746A1 US 97547401 A US97547401 A US 97547401A US 2003048746 A1 US2003048746 A1 US 2003048746A1
- Authority
- US
- United States
- Prior art keywords
- switch
- network
- vlan
- failover
- ports
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/35—Switches specially adapted for specific applications
- H04L49/356—Switches specially adapted for specific applications for storage area networks
- H04L49/357—Fibre channel switches
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/2852—Metropolitan area networks
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/46—Interconnection of networks
- H04L12/4637—Interconnected ring systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
- H04L69/40—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/35—Switches specially adapted for specific applications
- H04L49/351—Switches specially adapted for specific applications for local area network [LAN], e.g. Ethernet switches
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/35—Switches specially adapted for specific applications
- H04L49/354—Switches specially adapted for specific applications for supporting virtual local area networks [VLAN]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/60—Software-defined switches
- H04L49/602—Multilayer or multiprotocol switching, e.g. IP switching
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q11/0067—Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q11/0071—Provisions for the electrical-optical layer interface
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q2011/0073—Provisions for forwarding or routing, e.g. lookup tables
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q2011/0079—Operation or maintenance aspects
- H04Q2011/0081—Fault tolerance; Redundancy; Recovery; Reconfigurability
Definitions
- the invention generally relates to the field of fiber optic communications networks, and more particularly to a new system and method for deploying and operating a metropolitan area local access distribution network.
- Fiber deployment in Metro Area Networks (“MANs”) has been primarily to carrier and service provider locations, or to a relatively small number of very large commercial office building sites. At the current time, it is estimated that as few as 10% of all commercial buildings in the United States are served with fiber-optic networks.
- a service network provides customers with a highly-available transparent Layer 2 network connection between their edge IP equipment and their subscribers' edge IP equipment.
- Layer 2 known as the bridging or switching layer, allows edge IP equipment addressing and attachment. It forwards packets based on the unique Media Access Control (“MAC”) address of each end station. Data packets consist of both infrastructure content, such as MAC addresses and other information, and end-user content.
- MAC Media Access Control
- Data packets consist of both infrastructure content, such as MAC addresses and other information, and end-user content.
- MAC Media Access Control
- At Layer 2 generally no modification is required to packet infrastructure content when going between like Layer 1 interfaces, like Ethernet to Fast Ethernet. However, minor changes to infrastructure content-not end-user data content-may occur when bridging between unlike types such as FDDI and Ethernet. Additionally, the Ethernet service can inter-connect customers to create an “extended” LAN service.
- Layer 3 known as the routing layer, provides logical partitioning of subnetworks, scalability, security, and Quality of Service (“QoS”). Therefore, it is desirable that the network remain transparent to Layer 3 protocols such as IP. This is accomplished by the combination of a particular network topology combined with failure detection/recovery mechanisms, as more fully described herein.
- Embodiments of the present invention may include the following advantages: (1) in the BDN, a dedicated pair of diversely routed optical fibers for each customer; (2) in the core, a dual physical overlay ring topology; (3) working and protection logical path connectivity; (4) no 802.1D Spanning Tree for recovery; (5) resilience to any single network failure in any device or link; (6) quick recovery times from failure relative to mechanisms based on Spanning Tree; and (7) a failure detection/recovery protocol that is not “active” on any devices other than the devices directly attached to the subscriber.
- FIG. 1 is a schematic diagram of a local distribution portion of an overall fiber optic network, illustrating the relationship between multiple subscribers disposed on collection loops connected to a hub facility via a feeder loop;
- FIG. 2 is a schematic diagram illustrating a typical longest path around an access distribution network
- FIG. 3 is a schematic diagram illustrating an alternative design with nested feeders
- FIG. 4 is a schematic diagram of a dual overlay ring topology within the core
- FIG. 5 is a schematic diagram of a working path and a protection path across the core connecting a subscriber's Layer 3 switch to its carrier/ISP;
- FIG. 6 is a simplified logical diagram of the end-to-end Ethernet service indicating where ESRP is utilized.
- a fiber optic transport network can generally be described in terms of three primary components: (i) a leased transport network (LTN), (ii) a leased distribution network (LDN); and (iii) a built distribution network (BDN), which may be a distribution network in accordance to the present invention (see FIGS. 1 - 6 ).
- LTN leased transport network
- LDN leased distribution network
- BDN built distribution network
- the LTN is the main transport layer of each metropolitan system. It typically consists of a high-bandwidth, flexible DWDM transport pipe used to connect customer locations (such as data centers, co-location hotels, and large customer POPs) to distribution networks.
- customer locations such as data centers, co-location hotels, and large customer POPs
- the distribution networks may comprise both LDN and BDN designs, though either may be excluded. Although similar in general purpose, an LDN and a BDN may use differing architectural approaches to bring traffic to the LTN. While the LDN typically relies on TDM (and sometimes WDM) electronics to multiplex traffic onto limited quantities of fiber, the distribution network according to the present invention uses larger quantities of fiber, enabling a reduced reliance upon multiplexing electronics.
- Each subscriber should have access to a route-diverse connection to the LTN hub.
- these connections are capable of supporting:
- Wavelength services 1000-LX/LH/ZX, OC-48/OC-48c).
- the distribution design is scalable and flexible enough to adapt to the eventual traffic needs of the network. Circuits from multiple subscribers should be reasonably segregated. Where feasible, the distribution architecture should ensure that work requested by one subscriber seldom impacts other subscribers.
- the distribution network comprises a major feeder ring 10 with a series of smaller, subtending collector rings 11 - 13 .
- collector rings are installed to follow city streets.
- Feeder ring 10 accesses at least one LTN Hub 20 , where the distribution network fiber may be terminated to high-density fiber distribution panels (FDPs).
- FDPs high-density fiber distribution panels
- One particular feature of any local distribution architecture is the quantity of fiber run on the distribution network.
- fiber counts will vary based on the logistics of the distribution area, a typical feeder ring 10 will contain 432 fibers, and typical collectors 11 - 13 each will contain 144 fibers. Laterals (e.g., 15 ) extend from the collector rings 11 - 13 to subscriber buildings (e.g., 17 ), and will typically contain 48 fibers.
- each collector ( 11 - 13 ) is preferably deployed with two splice points to the feeder 10 .
- fiber counts may be varied upwardly or downwardly without deviation from the present invention.
- the overall goal of the preferred embodiment is to provide, for each subscriber, optical service with at least one diversely-routed, dedicated fiber pair.
- Circuit protection Isolating each subscriber's optical service on a dedicated fiber pair reduces the possibility that work requested by one subscriber affects other subscribers. This represents a significant advantage in network accessibility when compared to designs that rely on multiple subscribers sharing a TDM resource.
- a primary goal of the preferred embodiment of the BDN design is to reduce the use of electronics at each subscriber site, electronic components will still be required for subscribers who elect to use electrical circuits (e.g., DS-3, 10-base, and 100-base). Electrical circuits must still be converted into optical circuits for transport around the BDN. Due to the distances within the BDN, single-mode fiber connectivity is the preferred embodiment to support the connection between the subscriber site and the hub location. Therefore, additional electronics may be required for subscribers who desire optical circuits when these subscribers occupy locations or operate equipment with an embedded base of Multi-Mode Fiber (“MMF”).
- MMF Multi-Mode Fiber
- FIG. 2 illustrates the longest optical path 25 around the distribution network. This calculation is the sum of the length of the longest collector (shown as 11 ) and the length of the feeder 20 .
- the longest optical path 25 is a significant limitation to be considered in the design of the distribution network, as discussed in greater detail below.
- distribution network fiber can be terminated to high-density Fiber Distribution Panels (FDPs).
- FDPs Fiber Distribution Panels
- subscriber circuits may be cross-connected to ADM equipment, Ethernet switches, or directly to an LTN DWDM system.
- the ADMs and Ethernet switches aggregate circuits with common destinations (e.g., customer locations) and transfer them to the LTN for transport around the metropolitan network.
- a lateral fiber offshoot can be deployed to connect the appropriate feeder 10 fibers to a low-density FDP on the subscriber's premises.
- this FDP will serve as a demarcation point between the distribution network and the subscriber equipment.
- an additional component can be placed at the subscriber's site. This component typically will be a media converter capable of converting an electrical signal into a higher-rate optical signal for transport over the distribution network.
- This converter equipment can usually be powered by the subscriber's AC power facilities, although a small UPS (Uninterruptible Power Supply) device may be required in cases where brownout protection is lacking from the subscriber's AC feed.
- UPS Uninterruptible Power Supply
- Access to multiple-tenant facilities may be similarly designed. A primary difference will often be the equipment location. Any necessary auxiliary electrical equipment (FDP, DSX, patch panel, SONET TDM, Ethernet switch, media converter) may be located either within a Minimum Point of Entry (MPOE) facility inside the building or within the subscriber's location. When it is located within the MPOE, such equipment preferably should be within a protected enclosure (e.g., a cage or locked cabinet). DC power (e.g., ⁇ 48V regulated with battery reserve) may be provided as an option in larger MPOE facilities. However, AC power with a UPS reserve is also feasible.
- Non-Dispersion Shifted Fiber (ND SF) is the preferred fiber for such distribution network deployment.
- NZ-DSF Non-Zero Dispersion Shifted Fibers
- MMF Multi-Mode Fiber
- a 48-count fiber bundle can be run in a single 1.5′′ conduit between the collectors 11 - 13 and subscriber facilities. As a result, most laterals will be single-threaded. A person of ordinary skill in the art will readily appreciate that dual-threaded laterals, and laterals of different fiber counts, may also be run.
- fusion or mechanical splices may be utilized. Mechanical splices are preferably used between the lateral and the Collector fibers. High quality mechanical splices can be obtained that provide typical insertion loss below 0.10 dB.
- Fusion splices are preferably utilized between the lateral and the FDP within the subscriber site. Fusion splices can routinely introduce insertion losses of less than 0.05 dB.
- a collector loop will consist of a 144-count fiber bundle run in a single 4′′ conduit.
- the 4′′ collector can compartmentalized, such as with individual 1.0′′ conduits or “MaxCell”® fabric inner ducts.
- the Collector fibers will utilize one of the Feeder's expansion conduits instead of the 4′′ conduit discussed above.
- Both ends of a Collector loop will not necessarily intersect the Feeder at the same physical location. Fusion splices are preferably utilized between the Collector and Feeder loops.
- feeder loop 10 will consist of a 288 or 432-count fiber bundle run in a single 1.5′′ conduit.
- fiber bundles of greater or lesser count may be used as appropriate.
- Additional conduits preferably will be included along the Feeder path to accommodate future growth.
- a Collector loop runs parallel to a Feeder loop, it is expected that the Collector will utilize one of the Feeder's surplus 1.5′′ conduits instead of the Collector's usual 4′′ conduit.
- Fusion splices should be utilized for all connections to and from Feeder loops. All fusion splices should introduce an insertion loss of no greater than 0.05 dB.
- Feeder 10 fibers can be spliced to pigtails and terminated in the Hub 20 location on initial installation. This reduces the frequency of adding new splices on the feeder loop 10 and reduces the interval required for service activation.
- additional electronic equipment can be deployed at either the subscriber facility or the hub 20 to provide intermediate-reach optics on both sides of the transmission link.
- the distribution network provider deploys a pair of nested Feeder rings 30 in each distribution network.
- the collectors 31 , 32 and 33 closest to the hub 20 are placed on the nested feeder 30 , while the collectors 40 , 41 and 42 located farther out are placed on the longer feeder 40 .
- FIG. 3 displays a generic example of this configuration.
- the longer feeder 40 can remain longer (e.g., more than 7 miles in circumference) without stranding capacity because the collectors closest to the LTN hub 20 have a shorter path available to them.
- the additional cross-section of fiber that completes the interior Feeder may increase the cost of the distribution network, it may also provide the opportunity to place one or more additional Collectors that would have otherwise been difficult to attach to the single Feeder design.
- the distribution network design can be directed based on the guidelines below.
- the longest subscriber path is calculated as follows.
- Each Collector has a corresponding longest circuit path.
- the longest circuit path can be defined as the sum of the circumference of the Collector and the longest route around the Feeder between the Collector and the Hub. This value represents the maximum distance that a subscriber circuit on that Collector can possibly travel en route to the Hub. This value is unique to each Collector on the distribution network. After calculating this value for each collector on the distribution network, the largest of these values would represent the longest subscriber path on that distribution network.
- Any distribution network that meets this requirement can be designed using the conventional single Feeder, multiple Collector architecture.
- any distribution network that falls in this category will encounter complications based on the optical link budget.
- the distribution network should be examined in detail to determine whether a nested feeder approach is appropriate.
- the nested feeder architecture is desirable when a significant portion of potential subscribers must traverse more than nine miles of fiber (longest route around the Feeder) to access the Hub or the additional cross section of fiber added to create an Interior Feeder allows the addition of a new, desirable Collector that would have otherwise been inaccessible.
- any distribution network in this classification gives rise to design problems as one begins to exceed the limits of both Gigabit Ethernet and SONET IR- 1 optics.
- either the distribution network may be configured to utilize the nested feeder architecture, or it can be redesigned to shorten the longest subscriber path.
- Subscribers purchasing SONET services can synchronize their equipment with the Network by line-timing from the optics of the ADM at the Hub.
- subscribers purchasing Ethernet services can line-time from the optics of the system Ethernet Switch at the Hub facility.
- this option is not available for wavelength services, as these circuits bypass any equipment that can connect to a BITS clock.
- Subscribers who desire wavelength services must therefore either provide their own clock source or line-time from the customer equipment that they logically attach to on the far end of the distribution network. Should either of these options be unavailable for a given subscriber circuit, there is still a likely option available to provide error-free service.
- Telcordia compliant devices should contain an internal SONET Minimum Clock (SMC) source or Stratum 3 clock source. Either should provide adequate synchronization for SONET signals. Any equipment free-running on a Stratum 3 or SMC source should operate error-free under normal conditions. The major perceptible difference will be an increase in the frequency of pointer justification events between interconnected devices.
- SMC SONET Minimum Clock
- SONET equipment installed at a subscriber site may be owned and maintained either by the distribution network operator or by the individual subscriber.
- Ethernet equipment installed at a subscriber site will generally be owned and maintained by the subscriber.
- All distribution network electronics installed at subscriber locations that are owned and maintained by the distribution network operator should be remotely manageable, and should be capable of forwarding alarm messages to the system NOC.
- SONET equipment will commonly utilize the SONET Section Data Communications Channel (SDCC) to communicate with the ADM equipment installed at the Hub.
- SDCC SONET Section Data Communications Channel
- a network of the type described herein be substantially always available.
- a desirable network architecture will provide fast recovery from failure to meet uptime objectives. Taking as an example Ethernet as the local loop technology, it is an objective that Ethernet services be highly available. This objective makes the elimination of any Spanning Tree Protocol (“STP”) from the architecture desirable.
- STP Spanning Tree Protocol
- STP is not used because otherwise, network recovery times may be of the order of minutes per failure.
- the network elements which provide redundancy need not be co-located with the primary network elements. This design technique reduces the probability that problems with the physical environment will interrupt service. Problems with software bugs or upgrades or configuration errors or changes can often be dealt with separately in the primary and secondary forwarding paths without completely interrupting service. Therefore, network-level redundancy can also reduce the impact of non-hardware failure mechanisms. With the redundancy provided by the network, each network device no longer needs to be configured for the ultimate in standalone fault tolerance. Redundant networks can be configured to fail-over automatically from primary to secondary facilities without operator intervention. The duration of service interruption is equal to the time it takes for fail-over to occur. Fail-over times as low as a few seconds are possible in this manner.
- the local services network (e.g., Ethernet) according to the preferred embodiment of the present invention comprises a dual overlay ring topology within the core. This topology is shown in FIG. 4. As can be seen, the dual overlay ring topology is a physical topology in which two complete physical paths are disposed to ensure that two data channels are available during normal periods of use so that at least one is available to communicate information in the event the other becomes unavailable.
- This physical topology allows the creation of a working path 50 and a protection path 52 across the network connecting each subscriber (L3 Switch 54 ) to their carrier/ISP (L3 Switches 56 , 58 ).
- the working path 50 can be provisioned on one ring while the protection path 52 can be provisioned on the other ring shown, creating the logical connectivity topology shown in FIG. 5.
- Logical connectivity may be accomplished in many ways, such as by using Ethernet Virtual LAN (VLAN) tagging, as defined in the IEEE 802.1Q standard.
- VLAN Virtual LAN
- a VLAN can be roughly equated to a broadcast domain. More specifically, VLANs can be seen as analogous to a group of end-stations, perhaps on multiple physical LAN segments, which are not constrained by their physical location and can communicate as if they were on a common LAN.
- the 802.1Q header adds two octets to the standard Ethernet frame.
- ports on the Ethernet switches e.g., 54
- the logical connectivity paths are created through the network. This process is somewhat analogous to creating a Permanent Virtual Circuit (“PVC”) in the Frame Relay or ATM environment.
- PVC Permanent Virtual Circuit
- ESRP Extreme Network's Standby Router Protocol
- Additional protocols may be implemented to support detection and recovery of failures that occur at the Carrier/ISP connection.
- Some of these protocols are Hot Standby Router Protocol (“HSRP”) and Virtual Router Redundancy Protocol (“VRRP”).
- HSRP Hot Standby Router Protocol
- VRRP Virtual Router Redundancy Protocol
- standard Layer 2 protection protocols such as 802.1D Spanning Tree are not required in some embodiments of the present invention.
- ESRP is a feature of the Extreme OS (operating system) that allows multiple switches to provide redundant services to users. In addition to providing Layer 3 routing redundancy for IP, ESRP also provides Layer 2 redundancy. The Layer 2 redundancy features of ESRP offer fast failure recovery and provide for a dual-homed system design generally independent of end-user attached equipment.
- ESRP is configured on a per-VLAN basis on each switch.
- This system utilizes ESRP in a two switch configuration, one master and one standby.
- the switches exchange keep-alive packets for each VLAN independently. Only one switch can actively provide Layer 2 switching for each VLAN.
- the switch performing the forwarding for a particular VLAN is considered the “master” for that VLAN.
- the other participating switch for the VLAN is in ‘standby’ mode.
- each participating switch uses the same MAC address and must be configured with the same IP address. It is possible for one switch to be master for one or more VLANs while being in standby for others, thus allowing the load to be split across participating switches.
- ESRP Extreme Discovery Protocol
- a switch If a switch is master, it actively provides Layer 2 switching between all the ports of that VLAN. Additionally, the switch exchanges ESRP packets with other switches that are in standby mode.
- a switch If a switch is in standby mode, it exchanges ESRP packets with other switches on that same VLAN. When a switch is in standby, it does not perform Layer 2 switching services for the VLAN. From a Layer 2 switching perspective, no forwarding occurs between the member ports of the VLAN. This prevents loops and maintains redundancy.
- ESRP can be configured to track connectivity to one or more specified VLANs as criteria for fail-over.
- the switch that has the greatest number of active ports for a particular VLAN takes highest precedence and will become master. If at any time the number of active ports for a particular VLAN on the master switch becomes less than the standby switch, the master switch automatically relinquishes master status and remains in standby mode.
- ESRP can be configured to track connectivity using a simple ping to any outside responder (ping tracking).
- the responder may represent the default route of the switch, or any device meaningful to network connectivity of the master ESRP switch. It should be noted that the responder must reside on a different VLAN than ESRP. The switch automatically relinquishes master status and remains in standby mode if a ping keep-alive fails three consecutive times.
- FIG. 6 depicts ESRP enabled in the switches ( 62 , 63 ) directly attached to the subscriber 60 .
- Port track is used to detect local failure of a link directly connected to these switches while ping track is used to detect core network failures. If a failure is detected anywhere along the active path 64 , ESRP will failover to allow traffic to flow on the standby path 65 .
- ESRP port count can be used to protect dual customer connections to the network.
- ESRP ping tracking is used to protect the core VLAN.
- VRRP or HSRP protects the Carrier/ISP L3 switch.
- a preferred embodiment of the network includes network enhancements, including Extreme Network's ESRP, to support rapid failover of subscriber equipment when a network or core failure occurs.
- ESRP Failover Link Transition Enhancement This enhancement refers to the ability of a “Master” ESRP switch, when transitioning to standby state to “bounce” or restart auto-negotiation on a set of physical ports. This enhancement will cause an end device to flush its Layer 2 forwarding database and cause it to re-broadcast immediately for a new path through the network. This provides the end station the ability to switch from the primary to the secondary path in a very short time.
- This enhancement relates to the ability of a “Master” ESRP switch, when transitioning to a standby state to “bounce” or restart auto-negotiation on a set of physical ports. This is useful in this architecture to inform an end-user Layer 2 device of a failure farther within the network that does not directly impact the end-user Layer 2 device.
- Typical Layer 3 switches use the Address Resolution Protocol (ARP) to populate their forwarding databases. This forwarding database determines which port packets are sent out on based on destination MAC address. Once this information is learned through the ARP process, typical Layer 2 devices will not modify this forwarding information unless one of two events occur.
- ARP Address Resolution Protocol
- a Loss of Signal occurs on the port or 2) the ARP max age timer expires.
- the ARP max age value is set to 5 minutes.
- the Layer 2 device will re-ARP to update its forwarding database information. Therefore, if a failure occurs within the core of the network that does not cause a LOS on the end-user device, that device will continue to forward packets into the network even though they cannot reach their ultimate destination until the ARP max age timer expires. This is known as a black hole situation.
- the enhancement proposed here prevents a black hole situation, by notifying the end device of the core failure by “bouncing” the port to force the equipment to re-ARP to update its forwarding database information immediately.
- the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
- ADM add/Drop Multiplexer.
- a SONET component capable of inserting and removing traffic to/from the SONET line payload.
- ADMs also commonly perform other functions, such as generating/processing APS commands and synchronizing the transport optics to an external clock source.
- APS Automatic Protection Switching.
- BDN Built Distribution Network. A portion of a network dedicated to the aggregation of multiple subscribers. A BDN typically utilizes fiber to provide dedicated fiber links between individual subscribers and a Hub facility.
- BITS Building Integrated Timing Source. A highly accurate and precise clock source used to synchronize multiple nodes on a SONET transport system.
- Chromatic Dispersion A linear effect that causes pulse broadening or compression within an optical transmission system. Chromatic Dispersion is occurs because different wavelengths of light travel at different velocities through the transmission media.
- Collector Loop A fiber loop (typically 144 ct) used to connect multiple subscribers to the larger Feeder loop on a BDN.
- Customer A business entity (such as an ISP or LEC) that provides telecommunications service within a Metropolitan area.
- the BDN operator typically will serve as an intermediate transport mechanism to connect subscribers to various customers.
- DMD Downifferential Mode Delay. A linear effect that degrades the quality of laser transmissions across MMF. A single laser transmission can inadvertently become subdivided upon ingress to MMF. These identical signals traverse unique transmission paths within the large core of MMF and leave the fiber offset in time.
- DS3 Digital Signal 3. A digital signal rate of approximately 44.736 Mb/s corresponding to the North American T3 designator. A plesiochronous transport protocol equivalent to 672 voice lines at 64 kb/s each.
- DWDM Dense Wavelength Division Multiplexing. A method of allowing multiple transmission signals to be transmitted simultaneously over a single fiber by giving each a unique frequency range (or wavelength) within the transmission spectrum. DWDM wavelengths within the C-Band are standardized by the ITU-T.
- Ethernet A standardized (IEEE 802.3) packet-based data transport protocol developed by Xerox Corporation.
- Ethernet Switch A device used to route data packets to their proper destination in an Ethernet-based transport network.
- FDP Fiber Distribution Panel. An enclosure built to organize, manage, and protect physical cross-connections between multiple fiber-optic cables.
- Feeder Loop A fiber loop (typically 432 ct) used to connect multiple collector loops to a Hub facility on a BDN.
- Fusion Splice The process of joining of two discrete fiber-optic cables via localized heating of the fiber ends. Fusion splices are typically characterized as permanent in nature and exhibit relatively minor loss ( ⁇ 0.05 dB) at the fusion point.
- Hub Facility A facility used to connect a distribution network (BDN or LDN) to a transport network (LTN) within a Metropolitan area.
- IR-1 A specification for transmission lasers and receiver photodiodes standardized by Telcordia. IR-1 optics typically provide a 13.0 dB link budget and are optimized for NDSF.
- ITU-T International Telecommunications Union—Telecommunications Standardizations Sector.
- multiple fibers e.g., 48 ct
- LDN Leased Distribution Network. A portion of a network dedicated to the aggregation of multiple subscribers. An LDN typically utilizes fiber to provide fiber links between individual subscribers and a Hub facility.
- LR-1 A specification for transmission lasers and receiver photodiodes standardized by Telcordia. LR-1 optics typically provide a 25 dB link budget and are optimized for NDSF.
- LTN Leased Transport Network. A portion of a network dedicated to connecting various Customer sites to Hub facilities. An LTN will typically utilize TDM and DWDM equipment over a small quantity of leased fiber.
- MCP Modal Conditioning Patch cord.
- Mechanical Splice The process of joining of two discrete fiber-optic cables by aligning them within a mechanical enclosure or adhesive media. Mechanical splices typically utilize an index-matching gel to reduce reflection at the splice point. Expect a moderate power loss (0.10 to 0.20 dB) at the splice point.
- Media Converter A generic classification of devices used to alter protocols and/or media of a transmitted signal.
- MMF Multi-Mode Fiber.
- MMF is typically utilized with LED-based optical transmission systems.
- Modal Distortion A linear effect that causes pulse broadening of transmission signals over MMF. Rays taking more direct paths (fewer reflections in the core) through the MMF core traverse the fiber more quickly than rays taking less direct paths. Modal distortion limits the bandwidth and distance of transmission links over MMF.
- MPOE Minimum Point of Entry. A common space within a multi-tenant building used to interconnect multiple tenants with common external telecommunications facilities.
- NDSF Non Dispersion-Shifted Fiber. Single-mode optical fiber with a nominal zero-dispersion wavelength within the conventional 1310 nm transmission window.
- NZ-DSF Non-Zero Dispersion-Shifted Fiber. Single-mode optical fiber with a nominal zero-dispersion wavelength shifted to reduce chromatic dispersion within the 1530 nm to 1560nm transmission window.
- OC-3 Optical Carrier 3.
- a synchronous transport protocol equivalent to 2016 voice lines at 64 kb/s each. Protocol is specified by Telcordia standards.
- OC-3c Optical Carrier 3, Concatenated.
- OC-12 Optical Carrier 12.
- OC-12c Optical Carrier 12, Concatenated.
- OC-48 Optical Carrier 48.
- OC-48c Optical Carrier 48, Concatenated.
- a non-channelized variant of the OC-48 primarily utilized for data transmissions over SONET. Protocol is specified by Telcordia standards.
- Plesiochronous The relationship between two transmission devices, where each is timed from similar, yet diverse clock sources. A slight difference in either frequency or phase must exist between the diverse clocks.
- POP Point of Presence. The physical facility in which interexchange carriers and local exchange carriers provide access services.
- SMF Single Mode Fiber. A type of optical fiber in which only a single transport path (mode) is available through the core at a given wavelength.
- SONET Synchronous Optical NETwork.
- Use of the SONET TDM protocol is primarily limited to North America.
- Splice Box An enclosure built to organize, manage, and protect physical splices between multiple fiber-optic cables.
- SR A specification for transmission lasers and receiver photodiodes standardized by Telcordia. SR optics typically provide an 8 dB link budget and are optimized for NDSF.
- Subscriber An end-user (or desired end-user) of a Customer's telecommunications service.
- a BDN operator typically will serve as an intermediate transport mechanism between subscribers and customers.
- Synchronous The relationship between two transmission devices, where both are timed from identical clock sources.
- the clocks must be identical in frequency and phase.
- TDM Time-Division Multiplexing. Combining multiple transmission signals into a common, higher-frequency bit-stream.
- WDM Wavelength-Division Multiplexing. A method of allowing multiple transmission signals to be transmitted simultaneously over a single fiber by giving each a unique frequency range (or wavelength) within the transmission spectrum.
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Computer Security & Cryptography (AREA)
- Data Exchanges In Wide-Area Networks (AREA)
- Small-Scale Networks (AREA)
- Optical Communication System (AREA)
- Time-Division Multiplex Systems (AREA)
Abstract
Description
- The invention generally relates to the field of fiber optic communications networks, and more particularly to a new system and method for deploying and operating a metropolitan area local access distribution network.
- The growth of the Internet has created unprecedented demand for high-speed broadband connectivity in telecommunications networks. However, access connections between corporate Local Area Networks (“LANs”) and existing service provider networks, such as those operated by long-haul carriers and Internet Service Providers (“ISPs”), generally have been limited to relatively slow, hard to provision Ti (1.5 Mbps) or DS-3 (45 Mbps) data speeds due to infrastructure limitations in most metropolitan areas.
- The lack of bandwidth throughout metropolitan areas is a function, principally, of two independent factors. First, there is a deficiency in high speed fiber optic access rings and/or fiber optic “tails” into major buildings in metro areas. Second, the existing metropolitan area carriers continue to use older, installed SONET (Synchronous Optical NETwork) architecture which, although it allows data streams of different formats to be combined onto a single high speed fiber optic synchronous data stream, cannot be scaled to meet future bandwidth requirements. Although customer demand for increased bandwidth has been growing at exponential rates, there is a mismatch between carrier long-haul backbones and metro area backbones on the one hand and local loop access on the other hand. Despite the aggressive deployment of fiber-optic networks nationwide, relatively little fiber has been deployed in the local access market or “last mile.” Fiber deployment in Metro Area Networks (“MANs”) has been primarily to carrier and service provider locations, or to a relatively small number of very large commercial office building sites. At the current time, it is estimated that as few as 10% of all commercial buildings in the United States are served with fiber-optic networks.
- Currently, most local connectivity service providers are primarily providing SONET-based services and are investing little in the services required for expanded local connectivity—e.g., Ethernet and Wavelength services. In general, existing local service providers have not moved forward to upgrade local fiber infrastructure to support these latter services.
- In order to provide compatibility and easy upgrading from existing services to new services, it is desirable to provide SONET, Ethernet and Wavelength services in the metropolitan and access segments of the communications infrastructure, making use of a common interface system and fiber optic cables. In this way, it is possible for customers to migrate smoothly and at an opportune time from the traditional SONET-based circuits to Ethernet circuits and, possibly, to transparent wavelengths. Such an evolutionary connectivity path enables customers to access the right amount of bandwidth at the right time.
- In accordance with the present invention, a service network provides customers with a highly-available
transparent Layer 2 network connection between their edge IP equipment and their subscribers' edge IP equipment. -
Layer 2, known as the bridging or switching layer, allows edge IP equipment addressing and attachment. It forwards packets based on the unique Media Access Control (“MAC”) address of each end station. Data packets consist of both infrastructure content, such as MAC addresses and other information, and end-user content. AtLayer 2, generally no modification is required to packet infrastructure content when going between likeLayer 1 interfaces, like Ethernet to Fast Ethernet. However, minor changes to infrastructure content-not end-user data content-may occur when bridging between unlike types such as FDDI and Ethernet. Additionally, the Ethernet service can inter-connect customers to create an “extended” LAN service. -
Layer 3, known as the routing layer, provides logical partitioning of subnetworks, scalability, security, and Quality of Service (“QoS”). Therefore, it is desirable that the network remain transparent toLayer 3 protocols such as IP. This is accomplished by the combination of a particular network topology combined with failure detection/recovery mechanisms, as more fully described herein. - Embodiments of the present invention may include the following advantages: (1) in the BDN, a dedicated pair of diversely routed optical fibers for each customer; (2) in the core, a dual physical overlay ring topology; (3) working and protection logical path connectivity; (4) no 802.1D Spanning Tree for recovery; (5) resilience to any single network failure in any device or link; (6) quick recovery times from failure relative to mechanisms based on Spanning Tree; and (7) a failure detection/recovery protocol that is not “active” on any devices other than the devices directly attached to the subscriber.
- Further features and advantages of the invention will appear more clearly from a reading of the detailed description of the preferred embodiments of the invention, which are given below by way of example only, and with reference to the accompanying drawings, in which like references indicate similar elements, and in which:
- FIG. 1 is a schematic diagram of a local distribution portion of an overall fiber optic network, illustrating the relationship between multiple subscribers disposed on collection loops connected to a hub facility via a feeder loop;
- FIG. 2 is a schematic diagram illustrating a typical longest path around an access distribution network;
- FIG. 3 is a schematic diagram illustrating an alternative design with nested feeders;
- FIG. 4 is a schematic diagram of a dual overlay ring topology within the core;
- FIG. 5 is a schematic diagram of a working path and a protection path across the core connecting a subscriber's
Layer 3 switch to its carrier/ISP; and - FIG. 6 is a simplified logical diagram of the end-to-end Ethernet service indicating where ESRP is utilized.
- A fiber optic transport network can generally be described in terms of three primary components: (i) a leased transport network (LTN), (ii) a leased distribution network (LDN); and (iii) a built distribution network (BDN), which may be a distribution network in accordance to the present invention (see FIGS.1-6).
- The LTN is the main transport layer of each metropolitan system. It typically consists of a high-bandwidth, flexible DWDM transport pipe used to connect customer locations (such as data centers, co-location hotels, and large customer POPs) to distribution networks.
- The distribution networks may comprise both LDN and BDN designs, though either may be excluded. Although similar in general purpose, an LDN and a BDN may use differing architectural approaches to bring traffic to the LTN. While the LDN typically relies on TDM (and sometimes WDM) electronics to multiplex traffic onto limited quantities of fiber, the distribution network according to the present invention uses larger quantities of fiber, enabling a reduced reliance upon multiplexing electronics.
- The following description will focus specifically on the architectural design and operation of a distribution network especially suitable for a BDN, though it may have other applications, particularly to an LDN. Detailed discussions of LTN and LDN designs may be found in other publicly available documents. The distribution network architecture maximizes the saturation of the potential subscriber base at minimal expense and is designed with the following criteria in mind.
- Each subscriber should have access to a route-diverse connection to the LTN hub. In a preferred embodiment, these connections are capable of supporting:
- (1) SONET services that require Line Overhead termination and Automatic Protection Switching (APS) controlled by the distribution network (DS-3, OC-3/OC-3c, OC-12/OC-12c, and OC-48/OC-48c).
- (2) Data devices with SONET interfaces that require Line Overhead termination, but may lack APS functionality (DS-3, OC-3c, OC-12c, and OC-48c).
- (3) Ethernet services (10, 100, and 1000 base).
- (4) Wavelength services (1000-LX/LH/ZX, OC-48/OC-48c).
- In a preferred embodiment, the distribution design is scalable and flexible enough to adapt to the eventual traffic needs of the network. Circuits from multiple subscribers should be reasonably segregated. Where feasible, the distribution architecture should ensure that work requested by one subscriber seldom impacts other subscribers.
- Referring now to FIG. 1, the distribution network comprises a
major feeder ring 10 with a series of smaller, subtending collector rings 11-13. In a common metropolitan-wide network design, collector rings are installed to follow city streets.Feeder ring 10 accesses at least one LTN Hub 20, where the distribution network fiber may be terminated to high-density fiber distribution panels (FDPs). - One particular feature of any local distribution architecture is the quantity of fiber run on the distribution network. Although fiber counts will vary based on the logistics of the distribution area, a
typical feeder ring 10 will contain 432 fibers, and typical collectors 11-13 each will contain 144 fibers. Laterals (e.g., 15) extend from the collector rings 11-13 to subscriber buildings (e.g., 17), and will typically contain 48 fibers. As shown, each collector (11-13) is preferably deployed with two splice points to thefeeder 10. A person of ordinary skill in the art will readily appreciate that fiber counts may be varied upwardly or downwardly without deviation from the present invention. The overall goal of the preferred embodiment is to provide, for each subscriber, optical service with at least one diversely-routed, dedicated fiber pair. - Select embodiments of the presently proposed distribution network architecture have the following advantages over conventional TDM and WDM distribution networks.
- (i) Lower cost—At the present time, the major cost associated with any new fiber run is the cost of opening and closing the trench. Since this cost is substantially independent of the number of fibers being run, the comparison between a bulk-fiber distribution network and a TDM-based distribution network (similar to the LDN design), for example, becomes mainly a comparison between costs of fiber versus electronics. On relatively short fiber runs (like a distribution network), additional fiber is generally less expensive than TDM electronics. When the costs associated with space, power, operation, maintenance, and management of the TDM electronics is added, the cost advantages of a bulk-fiber approach increase dramatically.
- (ii) Manageability—Connecting subscribers to a distribution network becomes a relatively simple task of splicing fibers between the subscriber building and the collector. This design eliminates an extra layer of TDM circuit provisioning and management. Requirements of TDM software upgrades and equipment failures are likewise reduced.
- (iii) Scalability—Since each subscriber's optical service may be on a dedicated fiber pair, significant capacity exists at the outset and there is no concern regarding TDM circuit fill ratios or provisioning anomalies. This design also minimizes the need for TDM reconfigurations to support capacity expansions.
- (iv) Circuit protection—Isolating each subscriber's optical service on a dedicated fiber pair reduces the possibility that work requested by one subscriber affects other subscribers. This represents a significant advantage in network accessibility when compared to designs that rely on multiple subscribers sharing a TDM resource.
- Although a primary goal of the preferred embodiment of the BDN design is to reduce the use of electronics at each subscriber site, electronic components will still be required for subscribers who elect to use electrical circuits (e.g., DS-3, 10-base, and 100-base). Electrical circuits must still be converted into optical circuits for transport around the BDN. Due to the distances within the BDN, single-mode fiber connectivity is the preferred embodiment to support the connection between the subscriber site and the hub location. Therefore, additional electronics may be required for subscribers who desire optical circuits when these subscribers occupy locations or operate equipment with an embedded base of Multi-Mode Fiber (“MMF”).
- FIG. 2 illustrates the longest
optical path 25 around the distribution network. This calculation is the sum of the length of the longest collector (shown as 11) and the length of thefeeder 20. The longestoptical path 25 is a significant limitation to be considered in the design of the distribution network, as discussed in greater detail below. - The physical connections of circuits and facilities on the distribution network are described in greater detail below. Exemplary subscriber connections can be found by reference to FIGS.3-7, discussed below.
- LTN Hubs
- At
LTN Hub 20 locations, distribution network fiber can be terminated to high-density Fiber Distribution Panels (FDPs). From these locations, subscriber circuits may be cross-connected to ADM equipment, Ethernet switches, or directly to an LTN DWDM system. The ADMs and Ethernet switches aggregate circuits with common destinations (e.g., customer locations) and transfer them to the LTN for transport around the metropolitan network. - Single-Tenant Subscriber Facilities
- In a single-tenant subscriber facility, a lateral fiber offshoot can be deployed to connect the
appropriate feeder 10 fibers to a low-density FDP on the subscriber's premises. For optical services, this FDP will serve as a demarcation point between the distribution network and the subscriber equipment. For electrical services, an additional component can be placed at the subscriber's site. This component typically will be a media converter capable of converting an electrical signal into a higher-rate optical signal for transport over the distribution network. This converter equipment can usually be powered by the subscriber's AC power facilities, although a small UPS (Uninterruptible Power Supply) device may be required in cases where brownout protection is lacking from the subscriber's AC feed. - Multiple-Tenant Subscriber Facilities
- Access to multiple-tenant facilities may be similarly designed. A primary difference will often be the equipment location. Any necessary auxiliary electrical equipment (FDP, DSX, patch panel, SONET TDM, Ethernet switch, media converter) may be located either within a Minimum Point of Entry (MPOE) facility inside the building or within the subscriber's location. When it is located within the MPOE, such equipment preferably should be within a protected enclosure (e.g., a cage or locked cabinet). DC power (e.g., −48V regulated with battery reserve) may be provided as an option in larger MPOE facilities. However, AC power with a UPS reserve is also feasible.
- Fiber Plant
- At present, the majority of optical circuits transported over the distribution network preferably will utilize 1310 nm lasers and therefore, Non-Dispersion Shifted Fiber (ND SF) is the preferred fiber for such distribution network deployment. Non-Zero Dispersion Shifted Fibers (NZ-DSF) and Multi-Mode Fiber (MMF), though not presently preferred, may be used in alternative embodiments.
- Subscriber Laterals
- Normally, a 48-count fiber bundle can be run in a single 1.5″ conduit between the collectors11-13 and subscriber facilities. As a result, most laterals will be single-threaded. A person of ordinary skill in the art will readily appreciate that dual-threaded laterals, and laterals of different fiber counts, may also be run. Depending on system requirements, fusion or mechanical splices may be utilized. Mechanical splices are preferably used between the lateral and the Collector fibers. High quality mechanical splices can be obtained that provide typical insertion loss below 0.10 dB. Fusion splices are preferably utilized between the lateral and the FDP within the subscriber site. Fusion splices can routinely introduce insertion losses of less than 0.05 dB.
- Collector Loops
- In a preferred embodiment, a collector loop will consist of a 144-count fiber bundle run in a single 4″ conduit. The 4″ collector can compartmentalized, such as with individual 1.0″ conduits or “MaxCell”® fabric inner ducts. In cases where a single Collector runs in the same trench as a Feeder loop, it is expected that the Collector fibers will utilize one of the Feeder's expansion conduits instead of the 4″ conduit discussed above. Both ends of a Collector loop will not necessarily intersect the Feeder at the same physical location. Fusion splices are preferably utilized between the Collector and Feeder loops.
- In order to minimize the frequency of adding new splices between Collector and Feeder loops, a reasonable quantity of splices will be generated at the outset to cover the near-term growth of traffic on the distribution network.
- Feeder Loops
- In most cases,
feeder loop 10 will consist of a 288 or 432-count fiber bundle run in a single 1.5″ conduit. A person of ordinary skill in the art will readily appreciate that fiber bundles of greater or lesser count may be used as appropriate. Additional conduits preferably will be included along the Feeder path to accommodate future growth. In cases where a Collector loop runs parallel to a Feeder loop, it is expected that the Collector will utilize one of the Feeder's surplus 1.5″ conduits instead of the Collector's usual 4″ conduit. Fusion splices should be utilized for all connections to and from Feeder loops. All fusion splices should introduce an insertion loss of no greater than 0.05 dB. -
Feeder 10 fibers can be spliced to pigtails and terminated in theHub 20 location on initial installation. This reduces the frequency of adding new splices on thefeeder loop 10 and reduces the interval required for service activation. - An Alternative Embodiment—Additional Equipment
- In this embodiment, in addition to the conventional feeder/collector architecture, additional electronic equipment can be deployed at either the subscriber facility or the
hub 20 to provide intermediate-reach optics on both sides of the transmission link. - For example, with respect to SONET equipment, a series of ADMs will already exist at the hub locations to aggregate subscriber traffic, and IR-1 optics can be supported on each optical interface of the ADMs. Wavelength services pose a more complex problem. Since these services enter the DWDM directly at the Hub, they are limited by the current SR client-side interface on the DWDM equipment. Since it is unlikely that any wavelength service below an OC-48 or Gigabit Ethernet data rate will be used in this context (as this would require dedicating a DWDM wavelength to an OC-3 or OC-12 rate circuit), this would only pose a problem for OC-48 or Gigabit Ethernet wavelength services.
- In the case of Gigabit Ethernet services, upgrading a subscriber to a GBIC equivalent to the Finisar 1319-5A-30 would improve the optical reach to roughly 16.3 miles. This is less than one mile shorter than the range of a bi-directional IR-1 link. The OC-48/OC-48c case is more difficult. To support this service, a subscriber positioned near a Hub either should use LR-1 optics (assuming they are available on the subscriber equipment), or place an OC-48 regenerator at the Hub location.
- Second Alternative Embodiment—Nested Feeders
- In this scenario, the distribution network provider deploys a pair of nested Feeder rings30 in each distribution network. The
collectors hub 20 are placed on the nestedfeeder 30, while thecollectors longer feeder 40. FIG. 3 displays a generic example of this configuration. With the FIG. 3 type of configuration, thelonger feeder 40 can remain longer (e.g., more than 7 miles in circumference) without stranding capacity because the collectors closest to theLTN hub 20 have a shorter path available to them. - Although the additional cross-section of fiber that completes the interior Feeder may increase the cost of the distribution network, it may also provide the opportunity to place one or more additional Collectors that would have otherwise been difficult to attach to the single Feeder design.
- Decision Rule for Distribution Network Variants
- In significant part, the distribution network design can be directed based on the guidelines below. In each case, the longest subscriber path is calculated as follows. Each Collector has a corresponding longest circuit path. The longest circuit path can be defined as the sum of the circumference of the Collector and the longest route around the Feeder between the Collector and the Hub. This value represents the maximum distance that a subscriber circuit on that Collector can possibly travel en route to the Hub. This value is unique to each Collector on the distribution network. After calculating this value for each collector on the distribution network, the largest of these values would represent the longest subscriber path on that distribution network.
- Longest Subscriber Path is less than 9 Miles
- Any distribution network that meets this requirement can be designed using the conventional single Feeder, multiple Collector architecture.
- Longest Subscriber Path is between 9 and 16 Miles
- Any distribution network that falls in this category will encounter complications based on the optical link budget. With this in mind, the distribution network should be examined in detail to determine whether a nested feeder approach is appropriate. In most cases, the nested feeder architecture is desirable when a significant portion of potential subscribers must traverse more than nine miles of fiber (longest route around the Feeder) to access the Hub or the additional cross section of fiber added to create an Interior Feeder allows the addition of a new, desirable Collector that would have otherwise been inaccessible.
- Longest Subscriber Path is greater than 16 Miles
- Any distribution network in this classification gives rise to design problems as one begins to exceed the limits of both Gigabit Ethernet and SONET IR-1 optics. In this case, either the distribution network may be configured to utilize the nested feeder architecture, or it can be redesigned to shorten the longest subscriber path.
- Synchronization
- Subscribers purchasing SONET services can synchronize their equipment with the Network by line-timing from the optics of the ADM at the Hub. Similarly, subscribers purchasing Ethernet services can line-time from the optics of the system Ethernet Switch at the Hub facility. However, this option is not available for wavelength services, as these circuits bypass any equipment that can connect to a BITS clock. Subscribers who desire wavelength services must therefore either provide their own clock source or line-time from the customer equipment that they logically attach to on the far end of the distribution network. Should either of these options be unavailable for a given subscriber circuit, there is still a likely option available to provide error-free service. Depending on the age of the equipment, Telcordia compliant devices should contain an internal SONET Minimum Clock (SMC) source or
Stratum 3 clock source. Either should provide adequate synchronization for SONET signals. Any equipment free-running on aStratum 3 or SMC source should operate error-free under normal conditions. The major perceptible difference will be an increase in the frequency of pointer justification events between interconnected devices. - Depending on the situation, SONET equipment installed at a subscriber site may be owned and maintained either by the distribution network operator or by the individual subscriber. Ethernet equipment installed at a subscriber site will generally be owned and maintained by the subscriber.
- All distribution network electronics installed at subscriber locations that are owned and maintained by the distribution network operator should be remotely manageable, and should be capable of forwarding alarm messages to the system NOC. SONET equipment will commonly utilize the SONET Section Data Communications Channel (SDCC) to communicate with the ADM equipment installed at the Hub.
- The Ethernet Services Network
- Resiliency
- It is desirable that a network of the type described herein be substantially always available. In addition, a desirable network architecture will provide fast recovery from failure to meet uptime objectives. Taking as an example Ethernet as the local loop technology, it is an objective that Ethernet services be highly available. This objective makes the elimination of any Spanning Tree Protocol (“STP”) from the architecture desirable. In a preferred embodiment, STP is not used because otherwise, network recovery times may be of the order of minutes per failure.
- The network elements which provide redundancy need not be co-located with the primary network elements. This design technique reduces the probability that problems with the physical environment will interrupt service. Problems with software bugs or upgrades or configuration errors or changes can often be dealt with separately in the primary and secondary forwarding paths without completely interrupting service. Therefore, network-level redundancy can also reduce the impact of non-hardware failure mechanisms. With the redundancy provided by the network, each network device no longer needs to be configured for the ultimate in standalone fault tolerance. Redundant networks can be configured to fail-over automatically from primary to secondary facilities without operator intervention. The duration of service interruption is equal to the time it takes for fail-over to occur. Fail-over times as low as a few seconds are possible in this manner.
- Dual Physical Overlay Ring Core Topology
- The local services network (e.g., Ethernet) according to the preferred embodiment of the present invention comprises a dual overlay ring topology within the core. This topology is shown in FIG. 4. As can be seen, the dual overlay ring topology is a physical topology in which two complete physical paths are disposed to ensure that two data channels are available during normal periods of use so that at least one is available to communicate information in the event the other becomes unavailable.
- This physical topology allows the creation of a working
path 50 and aprotection path 52 across the network connecting each subscriber (L3 Switch 54) to their carrier/ISP (L3 Switches 56, 58). The workingpath 50 can be provisioned on one ring while theprotection path 52 can be provisioned on the other ring shown, creating the logical connectivity topology shown in FIG. 5. - Logical connectivity may be accomplished in many ways, such as by using Ethernet Virtual LAN (VLAN) tagging, as defined in the IEEE 802.1Q standard. A VLAN can be roughly equated to a broadcast domain. More specifically, VLANs can be seen as analogous to a group of end-stations, perhaps on multiple physical LAN segments, which are not constrained by their physical location and can communicate as if they were on a common LAN. The 802.1Q header adds two octets to the standard Ethernet frame. By configuring ports on the Ethernet switches (e.g.,54) to be part of the specific customer's VLAN, the logical connectivity paths are created through the network. This process is somewhat analogous to creating a Permanent Virtual Circuit (“PVC”) in the Frame Relay or ATM environment.
- Extreme Network's Standby Router Protocol (“ESRP”) may be used to detect and recover from failures that occur within the Ethernet Network. Additional protocols may be implemented to support detection and recovery of failures that occur at the Carrier/ISP connection. Some of these protocols are Hot Standby Router Protocol (“HSRP”) and Virtual Router Redundancy Protocol (“VRRP”). Note that
standard Layer 2 protection protocols such as 802.1D Spanning Tree are not required in some embodiments of the present invention. - Overview of ESRP
- ESRP is a feature of the Extreme OS (operating system) that allows multiple switches to provide redundant services to users. In addition to providing
Layer 3 routing redundancy for IP, ESRP also providesLayer 2 redundancy. TheLayer 2 redundancy features of ESRP offer fast failure recovery and provide for a dual-homed system design generally independent of end-user attached equipment. - ESRP is configured on a per-VLAN basis on each switch. This system utilizes ESRP in a two switch configuration, one master and one standby. The switches exchange keep-alive packets for each VLAN independently. Only one switch can actively provide
Layer 2 switching for each VLAN. The switch performing the forwarding for a particular VLAN is considered the “master” for that VLAN. The other participating switch for the VLAN is in ‘standby’ mode. - For a VLAN with ESRP enabled, each participating switch uses the same MAC address and must be configured with the same IP address. It is possible for one switch to be master for one or more VLANs while being in standby for others, thus allowing the load to be split across participating switches.
- To have two or more switches participate in ESRP, the following must be true. For each VLAN to be made redundant, the switches must have the ability to exchange packets on the
same Layer 2 broadcast domain for that VLAN. Multiple paths of exchange can be used, and typically exist in most network system designs that take advantage of ESRP. In order for a VLAN to be recognized as participating in ESRP, the assigned IP address for the separate switches must be identical. ESRP must be enabled on the desired VLANs for each switch. Extreme Discovery Protocol (EDP) must be enabled on the ports that are members of the ESRP VLANs. - Master Switch Behavior
- If a switch is master, it actively provides
Layer 2 switching between all the ports of that VLAN. Additionally, the switch exchanges ESRP packets with other switches that are in standby mode. - Standby Switch Behavior
- If a switch is in standby mode, it exchanges ESRP packets with other switches on that same VLAN. When a switch is in standby, it does not perform
Layer 2 switching services for the VLAN. From aLayer 2 switching perspective, no forwarding occurs between the member ports of the VLAN. This prevents loops and maintains redundancy. - ESRP Tracking
- ESRP can be configured to track connectivity to one or more specified VLANs as criteria for fail-over. The switch that has the greatest number of active ports for a particular VLAN takes highest precedence and will become master. If at any time the number of active ports for a particular VLAN on the master switch becomes less than the standby switch, the master switch automatically relinquishes master status and remains in standby mode.
- Additionally, ESRP can be configured to track connectivity using a simple ping to any outside responder (ping tracking). The responder may represent the default route of the switch, or any device meaningful to network connectivity of the master ESRP switch. It should be noted that the responder must reside on a different VLAN than ESRP. The switch automatically relinquishes master status and remains in standby mode if a ping keep-alive fails three consecutive times.
- A simplified drawing of the logical topology is shown in FIG. 6, indicating where ESRP is utilized in the present distribution network design. FIG. 6 depicts ESRP enabled in the switches (62, 63) directly attached to the subscriber 60. Port track is used to detect local failure of a link directly connected to these switches while ping track is used to detect core network failures. If a failure is detected anywhere along the
active path 64, ESRP will failover to allow traffic to flow on thestandby path 65. As shown, ESRP port count can be used to protect dual customer connections to the network. ESRP ping tracking is used to protect the core VLAN. In the exemplary embodiment shown, VRRP or HSRP protects the Carrier/ISP L3 switch. - ESRP Enhancements
- A preferred embodiment of the network includes network enhancements, including Extreme Network's ESRP, to support rapid failover of subscriber equipment when a network or core failure occurs. In the context of ESRP, this is referred to as “ESRP Failover Link Transition Enhancement.” This enhancement refers to the ability of a “Master” ESRP switch, when transitioning to standby state to “bounce” or restart auto-negotiation on a set of physical ports. This enhancement will cause an end device to flush its
Layer 2 forwarding database and cause it to re-broadcast immediately for a new path through the network. This provides the end station the ability to switch from the primary to the secondary path in a very short time. - This enhancement relates to the ability of a “Master” ESRP switch, when transitioning to a standby state to “bounce” or restart auto-negotiation on a set of physical ports. This is useful in this architecture to inform an end-
user Layer 2 device of a failure farther within the network that does not directly impact the end-user Layer 2 device. As background:Typical Layer 3 switches use the Address Resolution Protocol (ARP) to populate their forwarding databases. This forwarding database determines which port packets are sent out on based on destination MAC address. Once this information is learned through the ARP process,typical Layer 2 devices will not modify this forwarding information unless one of two events occur. First, a Loss of Signal (LOS) occurs on the port or 2) the ARP max age timer expires. Typically, the ARP max age value is set to 5 minutes. When this timer expires, theLayer 2 device will re-ARP to update its forwarding database information. Therefore, if a failure occurs within the core of the network that does not cause a LOS on the end-user device, that device will continue to forward packets into the network even though they cannot reach their ultimate destination until the ARP max age timer expires. This is known as a black hole situation. The enhancement proposed here prevents a black hole situation, by notifying the end device of the core failure by “bouncing” the port to force the equipment to re-ARP to update its forwarding database information immediately. - Although certain preferred embodiments of the present invention have been described above by way of example, it will be understood that modifications may be made to the disclosed embodiments without departing from the scope of the invention, which is defined by the appended claims. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
- ADM—Add/Drop Multiplexer. A SONET component capable of inserting and removing traffic to/from the SONET line payload. ADMs also commonly perform other functions, such as generating/processing APS commands and synchronizing the transport optics to an external clock source.
- APS—Automatic Protection Switching. A SONET fault recovery protocol standardized by Telcordia. APS will generally provide fault recovery in less than 50 ms.
- BDN—Built Distribution Network. A portion of a network dedicated to the aggregation of multiple subscribers. A BDN typically utilizes fiber to provide dedicated fiber links between individual subscribers and a Hub facility.
- BITS—Building Integrated Timing Source. A highly accurate and precise clock source used to synchronize multiple nodes on a SONET transport system.
- Chromatic Dispersion—A linear effect that causes pulse broadening or compression within an optical transmission system. Chromatic Dispersion is occurs because different wavelengths of light travel at different velocities through the transmission media.
- Collector Loop—A fiber loop (typically 144 ct) used to connect multiple subscribers to the larger Feeder loop on a BDN.
- Customer—A business entity (such as an ISP or LEC) that provides telecommunications service within a Metropolitan area. The BDN operator typically will serve as an intermediate transport mechanism to connect subscribers to various customers.
- DMD—Differential Mode Delay. A linear effect that degrades the quality of laser transmissions across MMF. A single laser transmission can inadvertently become subdivided upon ingress to MMF. These identical signals traverse unique transmission paths within the large core of MMF and leave the fiber offset in time.
- DS3—
Digital Signal 3. A digital signal rate of approximately 44.736 Mb/s corresponding to the North American T3 designator. A plesiochronous transport protocol equivalent to 672 voice lines at 64 kb/s each. - DWDM—Dense Wavelength Division Multiplexing. A method of allowing multiple transmission signals to be transmitted simultaneously over a single fiber by giving each a unique frequency range (or wavelength) within the transmission spectrum. DWDM wavelengths within the C-Band are standardized by the ITU-T.
- Ethernet—A standardized (IEEE 802.3) packet-based data transport protocol developed by Xerox Corporation.
- Ethernet Switch—A device used to route data packets to their proper destination in an Ethernet-based transport network.
- FDP—Fiber Distribution Panel. An enclosure built to organize, manage, and protect physical cross-connections between multiple fiber-optic cables.
- Feeder Loop—A fiber loop (typically 432 ct) used to connect multiple collector loops to a Hub facility on a BDN.
- Fusion Splice—The process of joining of two discrete fiber-optic cables via localized heating of the fiber ends. Fusion splices are typically characterized as permanent in nature and exhibit relatively minor loss (<0.05 dB) at the fusion point.
- Hub Facility—A facility used to connect a distribution network (BDN or LDN) to a transport network (LTN) within a Metropolitan area.
- IR-1—A specification for transmission lasers and receiver photodiodes standardized by Telcordia. IR-1 optics typically provide a 13.0 dB link budget and are optimized for NDSF.
- ITU-T—International Telecommunications Union—Telecommunications Standardizations Sector.
- Lateral—A fiber spur containing multiple fibers (e.g., 48 ct) used to connect a Collector loop to a subscriber site.
- LDN—Leased Distribution Network. A portion of a network dedicated to the aggregation of multiple subscribers. An LDN typically utilizes fiber to provide fiber links between individual subscribers and a Hub facility.
- LR-1—A specification for transmission lasers and receiver photodiodes standardized by Telcordia. LR-1 optics typically provide a 25 dB link budget and are optimized for NDSF.
- LTN—Leased Transport Network. A portion of a network dedicated to connecting various Customer sites to Hub facilities. An LTN will typically utilize TDM and DWDM equipment over a small quantity of leased fiber.
- MCP—Modal Conditioning Patch cord. A hybrid fiber-optic cable used to overcome DMD problems by allowing a laser to mimic the overfilled launch characteristics of an LED.
- Mechanical Splice—The process of joining of two discrete fiber-optic cables by aligning them within a mechanical enclosure or adhesive media. Mechanical splices typically utilize an index-matching gel to reduce reflection at the splice point. Expect a moderate power loss (0.10 to 0.20 dB) at the splice point.
- Media Converter—A generic classification of devices used to alter protocols and/or media of a transmitted signal.
- MMF—Multi-Mode Fiber. A fiber-optic cable with a relatively large (50 to 62 μm) transmission core that allows signals to traverse multiple, discrete transmission paths (modes) within the cable. MMF is typically utilized with LED-based optical transmission systems.
- Modal Distortion—A linear effect that causes pulse broadening of transmission signals over MMF. Rays taking more direct paths (fewer reflections in the core) through the MMF core traverse the fiber more quickly than rays taking less direct paths. Modal distortion limits the bandwidth and distance of transmission links over MMF.
- MPOE—Minimum Point of Entry. A common space within a multi-tenant building used to interconnect multiple tenants with common external telecommunications facilities.
- NDSF—Non Dispersion-Shifted Fiber. Single-mode optical fiber with a nominal zero-dispersion wavelength within the conventional 1310 nm transmission window.
- NZ-DSF—Non-Zero Dispersion-Shifted Fiber. Single-mode optical fiber with a nominal zero-dispersion wavelength shifted to reduce chromatic dispersion within the 1530 nm to 1560nm transmission window.
- OC-3—
Optical Carrier 3. The optical equivalent to an STS-3, with a digital signal rate of approximately 155.52 Mb/s. A synchronous transport protocol equivalent to 2016 voice lines at 64 kb/s each. Protocol is specified by Telcordia standards. - OC-3c—
Optical Carrier 3, Concatenated. A non-channelized variant of the OC-3, primarily utilized for data transmissions over SONET. Protocol is specified by Telcordia standards. - OC-12—
Optical Carrier 12. The optical equivalent to an STS-12, with a digital signal rate of approximately 622.08 Mb/s. A synchronous transport protocol equivalent to 8064 voice lines at 64 kb/s each. Protocol is specified by Telcordia standards. - OC-12c—
Optical Carrier 12, Concatenated. A non-channelized variant of the OC-12, primarily utilized for data transmissions over SONET. Protocol is specified by Telcordia standards. - OC-48—Optical Carrier 48. The optical equivalent to an STS-48, with a digital signal rate of approximately 2.488 Gb/s. A synchronous transport protocol equivalent to 32256 voice lines at 64 kb/s each. Protocol is specified by Telcordia standards.
- OC-48c—Optical Carrier 48, Concatenated. A non-channelized variant of the OC-48, primarily utilized for data transmissions over SONET. Protocol is specified by Telcordia standards.
- Plesiochronous—The relationship between two transmission devices, where each is timed from similar, yet diverse clock sources. A slight difference in either frequency or phase must exist between the diverse clocks.
- POP—Point of Presence. The physical facility in which interexchange carriers and local exchange carriers provide access services.
- SMF—Single Mode Fiber. A type of optical fiber in which only a single transport path (mode) is available through the core at a given wavelength.
- SONET—Synchronous Optical NETwork. A circuit-based transmission/restoration protocol defined by Telcordia standards. Use of the SONET TDM protocol is primarily limited to North America.
- Splice Box—An enclosure built to organize, manage, and protect physical splices between multiple fiber-optic cables.
- SR—A specification for transmission lasers and receiver photodiodes standardized by Telcordia. SR optics typically provide an 8 dB link budget and are optimized for NDSF.
- Subscriber—An end-user (or desired end-user) of a Customer's telecommunications service. A BDN operator typically will serve as an intermediate transport mechanism between subscribers and customers.
- Synchronous—The relationship between two transmission devices, where both are timed from identical clock sources. The clocks must be identical in frequency and phase.
- TDM—Time-Division Multiplexing. Combining multiple transmission signals into a common, higher-frequency bit-stream.
- WDM—Wavelength-Division Multiplexing. A method of allowing multiple transmission signals to be transmitted simultaneously over a single fiber by giving each a unique frequency range (or wavelength) within the transmission spectrum.
Claims (18)
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/975,474 US20030048746A1 (en) | 2001-09-12 | 2001-10-11 | Metropolitan area local access service system |
EP02784076A EP1435153B1 (en) | 2001-10-11 | 2002-10-10 | Metropolitan area local access service system |
AT02784076T ATE325483T1 (en) | 2001-10-11 | 2002-10-10 | SERVICE SYSTEM FOR LOCAL ACCESS IN A METROPOLITAN NETWORK |
DE60211191T DE60211191D1 (en) | 2001-10-11 | 2002-10-10 | SERVICE SYSTEM FOR LOCAL ACCESS IN A METROPOLITAN NETWORK |
PCT/US2002/032469 WO2004010653A1 (en) | 2001-10-11 | 2002-10-10 | Metropolitan area local access service system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/952,284 US20030048501A1 (en) | 2001-09-12 | 2001-09-12 | Metropolitan area local access service system |
US09/975,474 US20030048746A1 (en) | 2001-09-12 | 2001-10-11 | Metropolitan area local access service system |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/952,284 Continuation US20030048501A1 (en) | 2001-09-12 | 2001-09-12 | Metropolitan area local access service system |
Publications (1)
Publication Number | Publication Date |
---|---|
US20030048746A1 true US20030048746A1 (en) | 2003-03-13 |
Family
ID=25492743
Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/952,284 Abandoned US20030048501A1 (en) | 2001-09-12 | 2001-09-12 | Metropolitan area local access service system |
US09/975,474 Abandoned US20030048746A1 (en) | 2001-09-12 | 2001-10-11 | Metropolitan area local access service system |
US11/087,938 Expired - Fee Related US8031589B2 (en) | 2001-09-12 | 2005-03-23 | Metropolitan area local access service system |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/952,284 Abandoned US20030048501A1 (en) | 2001-09-12 | 2001-09-12 | Metropolitan area local access service system |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/087,938 Expired - Fee Related US8031589B2 (en) | 2001-09-12 | 2005-03-23 | Metropolitan area local access service system |
Country Status (3)
Country | Link |
---|---|
US (3) | US20030048501A1 (en) |
EP (1) | EP1425881A2 (en) |
WO (1) | WO2003024029A2 (en) |
Cited By (37)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030048501A1 (en) * | 2001-09-12 | 2003-03-13 | Michael Guess | Metropolitan area local access service system |
US20040081144A1 (en) * | 2002-09-17 | 2004-04-29 | Richard Martin | System and method for access point (AP) aggregation and resiliency in a hybrid wired/wireless local area network |
US20040098501A1 (en) * | 2002-10-29 | 2004-05-20 | Finn Norman W. | Multi-bridge lan aggregation |
US20040160895A1 (en) * | 2003-02-14 | 2004-08-19 | At&T Corp. | Failure notification method and system in an ethernet domain |
US20040165595A1 (en) * | 2003-02-25 | 2004-08-26 | At&T Corp. | Discovery and integrity testing method in an ethernet domain |
US20050007951A1 (en) * | 2003-07-11 | 2005-01-13 | Roger Lapuh | Routed split multilink trunking |
US20050022179A1 (en) * | 2003-07-21 | 2005-01-27 | Alcatel | Software replacement method and related software replacement system |
US20050031263A1 (en) * | 2002-08-29 | 2005-02-10 | Micron Technology, Inc. | Resistive heater for thermo optic device |
US20050147027A1 (en) * | 2002-08-30 | 2005-07-07 | Nokia Corporation | Method, system and hub for loop initialization |
US20050265676A1 (en) * | 2004-05-28 | 2005-12-01 | Ju-Chang Han | Optical fiber for metro network |
US20060093295A1 (en) * | 2004-11-02 | 2006-05-04 | Fujitsu Limited | Multimode fiber transmission system |
FR2882166A1 (en) * | 2005-02-16 | 2006-08-18 | Alcatel Sa | IP data conversion device for e.g. UMTS type network, has managing units to order Ethernet line protection units to place active and standby gateways in standby and active states, respectively, if units have not already placed them |
US20060245351A1 (en) * | 2005-05-02 | 2006-11-02 | Moni Pande | Method, apparatus, and system for improving ethernet ring convergence time |
US7145865B1 (en) * | 2002-06-26 | 2006-12-05 | Bellsouth Intellectual Property Corp. | Method for moving network elements with minimal network outages in an active ATM network |
US20070019642A1 (en) * | 2005-06-24 | 2007-01-25 | Infinera Corporation | Virtual local area network configuration for multi-chassis network element |
US20070076594A1 (en) * | 2005-09-16 | 2007-04-05 | Khan Mohiuddin M | Method and system of providing redundancy in a network device |
US7209435B1 (en) * | 2002-04-16 | 2007-04-24 | Foundry Networks, Inc. | System and method for providing network route redundancy across Layer 2 devices |
US20070140109A1 (en) * | 2003-12-12 | 2007-06-21 | Norbert Lobig | Method for protection switching of geographically separate switching systems |
US20070211730A1 (en) * | 2005-09-13 | 2007-09-13 | Richard Cuthbert | Message handling in a local area network having redundant paths |
US20080025332A1 (en) * | 2004-12-31 | 2008-01-31 | Huawei Technologies Co., Ltd. Huawei Administration Building | Method for Protecting Data Service in Metropolitan Transmission Network |
US20080089647A1 (en) * | 2002-08-29 | 2008-04-17 | Micron Technology, Inc | Resonator for thermo optic device |
US20080144634A1 (en) * | 2006-12-15 | 2008-06-19 | Nokia Corporation | Selective passive address resolution learning |
US20080226247A1 (en) * | 2002-08-29 | 2008-09-18 | Micron Technology, Inc. | Waveguide for thermo optic device |
CN100423495C (en) * | 2003-10-01 | 2008-10-01 | 日本电气株式会社 | Method and apparatus for resolving deadlock of auto-negotiation sequence between switches |
US20080313314A1 (en) * | 2005-01-28 | 2008-12-18 | Siemens Aktiengesellschaft | Method and Apparatus for Assigning Packet Addresses to a Plurality of Devices |
US20090175202A1 (en) * | 2005-09-23 | 2009-07-09 | Nokia Siemens Networks Gmbh & Co. Kg | Method for Augmenting a Network |
US20090274153A1 (en) * | 2002-10-01 | 2009-11-05 | Andrew Tai-Chin Kuo | System and method for implementation of layer 2 redundancy protocols across multiple networks |
US20100074265A1 (en) * | 2008-09-19 | 2010-03-25 | Oki Electronic Industry Co., Ltd. | Packet synchronization switching method and gateway device |
CN101980488A (en) * | 2010-10-22 | 2011-02-23 | 中兴通讯股份有限公司 | Address resolution protocol (ARP) table entry management method and three-layer exchanger |
WO2011026324A1 (en) * | 2009-09-02 | 2011-03-10 | 中兴通讯股份有限公司 | Distributed electrical cross device, and system and method thereof for implementing sub-network connection (snc) cascade protection |
US7911937B1 (en) * | 2003-05-30 | 2011-03-22 | Sprint Communications Company L.P. | Communication network architecture with diverse-distributed trunking and controlled protection schemes |
US20110258346A1 (en) * | 2008-06-27 | 2011-10-20 | Laith Said | Method and System for Link Aggregation |
US8218434B1 (en) * | 2004-10-15 | 2012-07-10 | Ciena Corporation | Ethernet facility and equipment protection |
US20120195189A1 (en) * | 2011-01-31 | 2012-08-02 | Dawei Wang | System and method for providing communication connection resilience |
US8264947B1 (en) * | 2005-06-15 | 2012-09-11 | Barclays Capital, Inc. | Fault tolerant wireless access system and method |
US8451711B1 (en) * | 2002-03-19 | 2013-05-28 | Cisco Technology, Inc. | Methods and apparatus for redirecting traffic in the presence of network address translation |
US8654630B2 (en) | 2010-03-19 | 2014-02-18 | Brocade Communications Systems, Inc. | Techniques for link redundancy in layer 2 networks |
Families Citing this family (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6717922B2 (en) * | 2002-03-04 | 2004-04-06 | Foundry Networks, Inc. | Network configuration protocol and method for rapid traffic recovery and loop avoidance in ring topologies |
US7489867B1 (en) * | 2002-05-06 | 2009-02-10 | Cisco Technology, Inc. | VoIP service over an ethernet network carried by a DWDM optical supervisory channel |
US7200331B2 (en) * | 2002-07-15 | 2007-04-03 | Lucent Technologies Inc. | Wavelength routing on an optical metro network subtended off an agile core optical network |
US7292542B2 (en) * | 2003-03-05 | 2007-11-06 | At&T Bls Intellectual Property, Inc. | Method for traffic engineering of connectionless virtual private network services |
US7345991B1 (en) * | 2003-05-28 | 2008-03-18 | Atrica Israel Ltd. | Connection protection mechanism for dual homed access, aggregation and customer edge devices |
WO2006071131A1 (en) * | 2004-12-27 | 2006-07-06 | Fragoso Freitas Simoes Fernand | Implementation method for a fixed optical communication network |
KR100694231B1 (en) * | 2006-01-16 | 2007-03-14 | 삼성전자주식회사 | Apparatus and mehtod for processing packet |
EP1865662A1 (en) * | 2006-06-08 | 2007-12-12 | Koninklijke KPN N.V. | Connection method and system for delivery of services to customers |
MX2009001629A (en) | 2006-08-21 | 2009-02-23 | Afl Telecommunications Llc | Fiber distribution hub. |
DE102007015449B4 (en) * | 2007-03-30 | 2009-09-17 | Siemens Ag | Method for reconfiguring a communication network |
DE102007015539B4 (en) * | 2007-03-30 | 2012-01-05 | Siemens Ag | Method for reconfiguring a communication network |
US7836360B2 (en) * | 2007-04-09 | 2010-11-16 | International Business Machines Corporation | System and method for intrusion prevention high availability fail over |
EP2206325A4 (en) * | 2007-10-12 | 2013-09-04 | Nortel Networks Ltd | Multi-point and rooted multi-point protection switching |
GB0906290D0 (en) * | 2009-04-09 | 2009-05-20 | Nomura Internat Plc | Ultra low latency securities trading infrastructure |
US8412042B2 (en) * | 2010-04-21 | 2013-04-02 | Cisco Technology, Inc. | Innovative architecture for fully non blocking service aggregation without O-E-O conversion in a DWDM multiring interconnection node |
US9491041B2 (en) * | 2011-03-07 | 2016-11-08 | Tejas Networks Limited | Ethernet chain protection switching |
US9264303B2 (en) | 2011-03-11 | 2016-02-16 | Tejas Networks Limited | Protection switching method and system provision by a distributed protection group |
DE102013110784B4 (en) * | 2012-10-05 | 2021-03-18 | Zte (Usa) Inc. | SERVICE-SENSITIVE FLEXIBLE IPOWDM NETWORK AND OPERATING PROCEDURES |
US9769058B2 (en) | 2013-05-17 | 2017-09-19 | Ciena Corporation | Resilient dual-homed data network hand-off |
EP3288221B1 (en) * | 2015-05-26 | 2020-05-06 | Nippon Telegraph And Telephone Corporation | Method and apparatus for reducing network delay in a passive optical network |
Citations (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4871225A (en) * | 1984-08-24 | 1989-10-03 | Pacific Bell | Fiber optic distribution network |
US5107490A (en) * | 1985-04-24 | 1992-04-21 | Artel Communications Corporation | Ring-type communication network |
US5418785A (en) * | 1992-06-04 | 1995-05-23 | Gte Laboratories Incorporated | Multiple-channel token ring network with single optical fiber utilizing subcarrier multiplexing with a dedicated control channel |
US5530782A (en) * | 1993-10-22 | 1996-06-25 | Sumitomo Electric Industries, Ltd. | Intermediate branching method for optical path |
US5835696A (en) * | 1995-11-22 | 1998-11-10 | Lucent Technologies Inc. | Data router backup feature |
US5920410A (en) * | 1994-06-08 | 1999-07-06 | British Telecommunications Public Limited Company | Access network |
US6088328A (en) * | 1998-12-29 | 2000-07-11 | Nortel Networks Corporation | System and method for restoring failed communication services |
US6108300A (en) * | 1997-05-02 | 2000-08-22 | Cisco Technology, Inc | Method and apparatus for transparently providing a failover network device |
US6236640B1 (en) * | 1997-02-03 | 2001-05-22 | Siemens Aktiengesellschaft | Method for alternate circuiting of transmission equipment in ring architectures for bidirectional transmission of ATM cells |
US6330229B1 (en) * | 1998-11-09 | 2001-12-11 | 3Com Corporation | Spanning tree with rapid forwarding database updates |
US6519399B2 (en) * | 2001-02-19 | 2003-02-11 | Corning Cable Systems Llc | Fiber optic cable with profiled group of optical fibers |
US6539022B1 (en) * | 1995-04-25 | 2003-03-25 | Enterasys Networks, Inc. | Network device with multicast forwarding data |
US6565269B2 (en) * | 2001-02-07 | 2003-05-20 | Fitel Usa Corp. | Systems and methods for low-loss splicing of optical fibers having a high concentration of fluorine to other types of optical fiber |
US20030179700A1 (en) * | 1999-01-15 | 2003-09-25 | Saleh Ali Najib | Method for restoring a virtual path in an optical network using 1‘protection |
US6654379B1 (en) * | 1998-10-08 | 2003-11-25 | Telecommunications Research Laboratories | Integrated ring-mesh network |
US20040081093A1 (en) * | 1998-02-03 | 2004-04-29 | Haddock Stephen R. | Policy based quality of service |
US6751191B1 (en) * | 1999-06-29 | 2004-06-15 | Cisco Technology, Inc. | Load sharing and redundancy scheme |
US6766482B1 (en) * | 2001-10-31 | 2004-07-20 | Extreme Networks | Ethernet automatic protection switching |
US6826158B2 (en) * | 2000-03-02 | 2004-11-30 | Onfiber Communications, Inc. | Broadband tree-configured ring for metropolitan area networks |
US6834056B2 (en) * | 2001-06-26 | 2004-12-21 | Occam Networks | Virtual local area network protection switching |
US6963575B1 (en) * | 2000-06-07 | 2005-11-08 | Yipes Enterprise Services, Inc. | Enhanced data switching/routing for multi-regional IP over fiber network |
US7246168B1 (en) * | 1998-11-19 | 2007-07-17 | Cisco Technology, Inc. | Technique for improving the interaction between data link switch backup peer devices and ethernet switches |
US7289428B2 (en) * | 2001-08-13 | 2007-10-30 | Tellabs Operations, Inc. | Inter-working mesh telecommunications networks |
Family Cites Families (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3071007B2 (en) * | 1991-10-22 | 2000-07-31 | 富士通株式会社 | Communication network control method |
FR2736777B1 (en) * | 1995-07-12 | 1997-08-08 | Alcatel Nv | OPTICAL TRANSMISSION NETWORK WITH WAVELENGTH MULTIPLEXING |
DE19526172C1 (en) * | 1995-07-18 | 1997-01-30 | Siemens Ag | Method for transmitting ATM digital signals from a program unit, in particular digital data-compressed video distribution signals |
US7430164B2 (en) * | 1998-05-04 | 2008-09-30 | Hewlett-Packard Development Company, L.P. | Path recovery on failure in load balancing switch protocols |
US6370110B1 (en) * | 1998-09-16 | 2002-04-09 | At&T Corp | Back-up restoration technique for SONET/SHD rings |
US6351582B1 (en) * | 1999-04-21 | 2002-02-26 | Nortel Networks Limited | Passive optical network arrangement |
US6415323B1 (en) * | 1999-09-03 | 2002-07-02 | Fastforward Networks | Proximity-based redirection system for robust and scalable service-node location in an internetwork |
US6512614B1 (en) * | 1999-10-12 | 2003-01-28 | At&T Corp. | WDM-based architecture for flexible switch placement in an access network |
US7164698B1 (en) * | 2000-03-24 | 2007-01-16 | Juniper Networks, Inc. | High-speed line interface for networking devices |
AU2001238090A1 (en) * | 2000-04-01 | 2001-10-15 | Corning Incorporated | Heating method and device |
US7009933B2 (en) * | 2001-01-30 | 2006-03-07 | Broadcom Corporation | Traffic policing of packet transfer in a dual speed hub |
US7058296B2 (en) * | 2001-03-12 | 2006-06-06 | Lucent Technologies Inc. | Design method for WDM optical networks including alternate routes for fault recovery |
US6470032B2 (en) * | 2001-03-20 | 2002-10-22 | Alloptic, Inc. | System and method for synchronizing telecom-related clocks in ethernet-based passive optical access network |
CA2392942C (en) * | 2001-07-10 | 2010-03-16 | Tropic Networks Inc. | Protection system and method for resilient packet ring (rpr) interconnection |
US7123836B2 (en) * | 2001-07-16 | 2006-10-17 | Avago Technologies Fiber Ip (Singapore) Pte. Ltd. | All-optical network distribution system |
EP1461890B1 (en) * | 2001-09-04 | 2008-12-17 | Rumi Sheryar Gonda | Method for supporting sdh/sonet aps on ethernet |
US20030048501A1 (en) * | 2001-09-12 | 2003-03-13 | Michael Guess | Metropolitan area local access service system |
US6826056B2 (en) * | 2001-12-11 | 2004-11-30 | Hewlett-Packard Development Company, L.P. | Systems for use with data storage devices |
US20030223379A1 (en) * | 2002-05-28 | 2003-12-04 | Xuguang Yang | Method and system for inter-domain loop protection using a hierarchy of loop resolving protocols |
-
2001
- 2001-09-12 US US09/952,284 patent/US20030048501A1/en not_active Abandoned
- 2001-10-11 US US09/975,474 patent/US20030048746A1/en not_active Abandoned
-
2002
- 2002-09-06 EP EP02768815A patent/EP1425881A2/en not_active Withdrawn
- 2002-09-06 WO PCT/US2002/028457 patent/WO2003024029A2/en not_active Application Discontinuation
-
2005
- 2005-03-23 US US11/087,938 patent/US8031589B2/en not_active Expired - Fee Related
Patent Citations (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4871225A (en) * | 1984-08-24 | 1989-10-03 | Pacific Bell | Fiber optic distribution network |
US5107490A (en) * | 1985-04-24 | 1992-04-21 | Artel Communications Corporation | Ring-type communication network |
US5418785A (en) * | 1992-06-04 | 1995-05-23 | Gte Laboratories Incorporated | Multiple-channel token ring network with single optical fiber utilizing subcarrier multiplexing with a dedicated control channel |
US5530782A (en) * | 1993-10-22 | 1996-06-25 | Sumitomo Electric Industries, Ltd. | Intermediate branching method for optical path |
US5920410A (en) * | 1994-06-08 | 1999-07-06 | British Telecommunications Public Limited Company | Access network |
US6539022B1 (en) * | 1995-04-25 | 2003-03-25 | Enterasys Networks, Inc. | Network device with multicast forwarding data |
US5835696A (en) * | 1995-11-22 | 1998-11-10 | Lucent Technologies Inc. | Data router backup feature |
US6236640B1 (en) * | 1997-02-03 | 2001-05-22 | Siemens Aktiengesellschaft | Method for alternate circuiting of transmission equipment in ring architectures for bidirectional transmission of ATM cells |
US6108300A (en) * | 1997-05-02 | 2000-08-22 | Cisco Technology, Inc | Method and apparatus for transparently providing a failover network device |
US20040081093A1 (en) * | 1998-02-03 | 2004-04-29 | Haddock Stephen R. | Policy based quality of service |
US6654379B1 (en) * | 1998-10-08 | 2003-11-25 | Telecommunications Research Laboratories | Integrated ring-mesh network |
US6330229B1 (en) * | 1998-11-09 | 2001-12-11 | 3Com Corporation | Spanning tree with rapid forwarding database updates |
US7246168B1 (en) * | 1998-11-19 | 2007-07-17 | Cisco Technology, Inc. | Technique for improving the interaction between data link switch backup peer devices and ethernet switches |
US6088328A (en) * | 1998-12-29 | 2000-07-11 | Nortel Networks Corporation | System and method for restoring failed communication services |
US20030179700A1 (en) * | 1999-01-15 | 2003-09-25 | Saleh Ali Najib | Method for restoring a virtual path in an optical network using 1‘protection |
US6751191B1 (en) * | 1999-06-29 | 2004-06-15 | Cisco Technology, Inc. | Load sharing and redundancy scheme |
US6826158B2 (en) * | 2000-03-02 | 2004-11-30 | Onfiber Communications, Inc. | Broadband tree-configured ring for metropolitan area networks |
US6963575B1 (en) * | 2000-06-07 | 2005-11-08 | Yipes Enterprise Services, Inc. | Enhanced data switching/routing for multi-regional IP over fiber network |
US6565269B2 (en) * | 2001-02-07 | 2003-05-20 | Fitel Usa Corp. | Systems and methods for low-loss splicing of optical fibers having a high concentration of fluorine to other types of optical fiber |
US6519399B2 (en) * | 2001-02-19 | 2003-02-11 | Corning Cable Systems Llc | Fiber optic cable with profiled group of optical fibers |
US6834056B2 (en) * | 2001-06-26 | 2004-12-21 | Occam Networks | Virtual local area network protection switching |
US7289428B2 (en) * | 2001-08-13 | 2007-10-30 | Tellabs Operations, Inc. | Inter-working mesh telecommunications networks |
US6766482B1 (en) * | 2001-10-31 | 2004-07-20 | Extreme Networks | Ethernet automatic protection switching |
Cited By (80)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030048501A1 (en) * | 2001-09-12 | 2003-03-13 | Michael Guess | Metropolitan area local access service system |
US8451711B1 (en) * | 2002-03-19 | 2013-05-28 | Cisco Technology, Inc. | Methods and apparatus for redirecting traffic in the presence of network address translation |
US9450893B2 (en) | 2002-04-16 | 2016-09-20 | Brocade Communications Systems, Inc. | System and method for providing network route redundancy across layer 2 devices |
US8014301B2 (en) * | 2002-04-16 | 2011-09-06 | Brocade Communications Systems, Inc. | System and method for providing network route redundancy across layer 2 devices |
US20090296565A1 (en) * | 2002-04-16 | 2009-12-03 | Foundry Networks, Inc. | System and method for providing network route redundancy across layer 2 devices |
US7558195B1 (en) | 2002-04-16 | 2009-07-07 | Foundry Networks, Inc. | System and method for providing network route redundancy across layer 2 devices |
US8593987B2 (en) | 2002-04-16 | 2013-11-26 | Brocade Communications Systems, Inc. | System and method for providing network route redundancy across layer 2 devices |
US7209435B1 (en) * | 2002-04-16 | 2007-04-24 | Foundry Networks, Inc. | System and method for providing network route redundancy across Layer 2 devices |
US7408874B2 (en) * | 2002-06-26 | 2008-08-05 | At&T Delaware Intellectual Property, Inc. | Method for moving network elements with minimal network outages in an active ATM network |
US20070242679A1 (en) * | 2002-06-26 | 2007-10-18 | Earl Meggison | Method for moving network elements with minimal network outages in an active atm network |
US7145865B1 (en) * | 2002-06-26 | 2006-12-05 | Bellsouth Intellectual Property Corp. | Method for moving network elements with minimal network outages in an active ATM network |
US20060098911A1 (en) * | 2002-08-29 | 2006-05-11 | Micron Technology, Inc. | Resistive heater for thermo optic device |
US7565039B2 (en) | 2002-08-29 | 2009-07-21 | Micron Technology, Inc. | Resistive heater for thermo optic device |
US7936955B2 (en) | 2002-08-29 | 2011-05-03 | Micron Technology, Inc. | Waveguide for thermo optic device |
US20060228084A1 (en) * | 2002-08-29 | 2006-10-12 | Micron Technology, Inc. | Resistive heater for thermo optic device |
US20100220958A1 (en) * | 2002-08-29 | 2010-09-02 | Blalock Guy T | Waveguide for thermo optic device |
US20110206332A1 (en) * | 2002-08-29 | 2011-08-25 | Blalock Guy T | Waveguide for thermo optic device |
US9042697B2 (en) | 2002-08-29 | 2015-05-26 | Micron Technology, Inc. | Resonator for thermo optic device |
US7720341B2 (en) | 2002-08-29 | 2010-05-18 | Micron Technology, Inc. | Waveguide for thermo optic device |
US7706647B2 (en) | 2002-08-29 | 2010-04-27 | Micron Technology, Inc. | Resistive heater for thermo optic device |
US8111965B2 (en) | 2002-08-29 | 2012-02-07 | Micron Technology, Inc. | Waveguide for thermo optic device |
US7509005B2 (en) | 2002-08-29 | 2009-03-24 | Micron Technology, Inc. | Resistive heater for thermo optic device |
US20050031263A1 (en) * | 2002-08-29 | 2005-02-10 | Micron Technology, Inc. | Resistive heater for thermo optic device |
US8195020B2 (en) | 2002-08-29 | 2012-06-05 | Micron Technology, Inc. | Resonator for thermo optic device |
US20080226247A1 (en) * | 2002-08-29 | 2008-09-18 | Micron Technology, Inc. | Waveguide for thermo optic device |
US20080089647A1 (en) * | 2002-08-29 | 2008-04-17 | Micron Technology, Inc | Resonator for thermo optic device |
US20050147027A1 (en) * | 2002-08-30 | 2005-07-07 | Nokia Corporation | Method, system and hub for loop initialization |
US20040081144A1 (en) * | 2002-09-17 | 2004-04-29 | Richard Martin | System and method for access point (AP) aggregation and resiliency in a hybrid wired/wireless local area network |
US8462668B2 (en) | 2002-10-01 | 2013-06-11 | Foundry Networks, Llc | System and method for implementation of layer 2 redundancy protocols across multiple networks |
US9391888B2 (en) | 2002-10-01 | 2016-07-12 | Foundry Networks, Llc | System and method for implementation of layer 2 redundancy protocols across multiple networks |
US20090274153A1 (en) * | 2002-10-01 | 2009-11-05 | Andrew Tai-Chin Kuo | System and method for implementation of layer 2 redundancy protocols across multiple networks |
US20040098501A1 (en) * | 2002-10-29 | 2004-05-20 | Finn Norman W. | Multi-bridge lan aggregation |
US10536296B2 (en) | 2002-10-29 | 2020-01-14 | Cisco Technology, Inc. | Multi-bridge LAN aggregation |
US8051211B2 (en) * | 2002-10-29 | 2011-11-01 | Cisco Technology, Inc. | Multi-bridge LAN aggregation |
US10530607B2 (en) | 2002-10-29 | 2020-01-07 | Cisco Technology, Inc. | Multi-bridge LAN aggregation |
US20040160895A1 (en) * | 2003-02-14 | 2004-08-19 | At&T Corp. | Failure notification method and system in an ethernet domain |
US20040165595A1 (en) * | 2003-02-25 | 2004-08-26 | At&T Corp. | Discovery and integrity testing method in an ethernet domain |
US7911937B1 (en) * | 2003-05-30 | 2011-03-22 | Sprint Communications Company L.P. | Communication network architecture with diverse-distributed trunking and controlled protection schemes |
US7463579B2 (en) * | 2003-07-11 | 2008-12-09 | Nortel Networks Limited | Routed split multilink trunking |
US20050007951A1 (en) * | 2003-07-11 | 2005-01-13 | Roger Lapuh | Routed split multilink trunking |
US8813068B2 (en) * | 2003-07-21 | 2014-08-19 | Alcatel Lucent | Software replacement method and related software replacement system |
US20050022179A1 (en) * | 2003-07-21 | 2005-01-27 | Alcatel | Software replacement method and related software replacement system |
CN100423495C (en) * | 2003-10-01 | 2008-10-01 | 日本电气株式会社 | Method and apparatus for resolving deadlock of auto-negotiation sequence between switches |
US8089980B2 (en) * | 2003-12-12 | 2012-01-03 | Siemens Aktiengesellschaft | Method for protection switching of geographically separate switching systems |
US20070140109A1 (en) * | 2003-12-12 | 2007-06-21 | Norbert Lobig | Method for protection switching of geographically separate switching systems |
US20050265676A1 (en) * | 2004-05-28 | 2005-12-01 | Ju-Chang Han | Optical fiber for metro network |
US7305165B2 (en) * | 2004-05-28 | 2007-12-04 | Samsung Electronics Co., Ltd. | Optical fiber for metro network |
US8218434B1 (en) * | 2004-10-15 | 2012-07-10 | Ciena Corporation | Ethernet facility and equipment protection |
US7454108B2 (en) * | 2004-11-02 | 2008-11-18 | Fujitsu Limited | Multimode fiber transmission system |
US20060093295A1 (en) * | 2004-11-02 | 2006-05-04 | Fujitsu Limited | Multimode fiber transmission system |
US20080025332A1 (en) * | 2004-12-31 | 2008-01-31 | Huawei Technologies Co., Ltd. Huawei Administration Building | Method for Protecting Data Service in Metropolitan Transmission Network |
US8416683B2 (en) * | 2004-12-31 | 2013-04-09 | Huawei Technologies Co., Ltd. | Method for protecting data service in metropolitan area transport network |
US7730168B2 (en) | 2005-01-28 | 2010-06-01 | Nokia Siemens Networks Gmbh & Co. Kg. | Method and apparatus for assigning packet addresses to a plurality of devices |
US20080313314A1 (en) * | 2005-01-28 | 2008-12-18 | Siemens Aktiengesellschaft | Method and Apparatus for Assigning Packet Addresses to a Plurality of Devices |
FR2882166A1 (en) * | 2005-02-16 | 2006-08-18 | Alcatel Sa | IP data conversion device for e.g. UMTS type network, has managing units to order Ethernet line protection units to place active and standby gateways in standby and active states, respectively, if units have not already placed them |
EP1694009A1 (en) * | 2005-02-16 | 2006-08-23 | Alcatel | Device having a high availability for translation of IP over ATM data in IP over Ethernet data |
US20060245351A1 (en) * | 2005-05-02 | 2006-11-02 | Moni Pande | Method, apparatus, and system for improving ethernet ring convergence time |
CN101151543B (en) * | 2005-05-02 | 2011-09-07 | 思科技术公司 | Method, apparatus, and system for improving Ethernet ring convergence time |
US7688716B2 (en) * | 2005-05-02 | 2010-03-30 | Cisco Technology, Inc. | Method, apparatus, and system for improving ethernet ring convergence time |
US8264947B1 (en) * | 2005-06-15 | 2012-09-11 | Barclays Capital, Inc. | Fault tolerant wireless access system and method |
US20070019642A1 (en) * | 2005-06-24 | 2007-01-25 | Infinera Corporation | Virtual local area network configuration for multi-chassis network element |
US7792017B2 (en) * | 2005-06-24 | 2010-09-07 | Infinera Corporation | Virtual local area network configuration for multi-chassis network element |
US8300646B2 (en) * | 2005-09-13 | 2012-10-30 | Siemens Enterprise Communications Gmbh & Co. Kg | Message handling in a local area network having redundant paths |
US20070211730A1 (en) * | 2005-09-13 | 2007-09-13 | Richard Cuthbert | Message handling in a local area network having redundant paths |
US7778268B2 (en) * | 2005-09-16 | 2010-08-17 | Acme Packet, Inc. | Method and system of providing redundancy in a network device |
US20070076594A1 (en) * | 2005-09-16 | 2007-04-05 | Khan Mohiuddin M | Method and system of providing redundancy in a network device |
US7885193B2 (en) | 2005-09-23 | 2011-02-08 | Nokia Siemens Networks Gmbh & Co. Kg | Method for augmenting a network |
US20090175202A1 (en) * | 2005-09-23 | 2009-07-09 | Nokia Siemens Networks Gmbh & Co. Kg | Method for Augmenting a Network |
US20080144634A1 (en) * | 2006-12-15 | 2008-06-19 | Nokia Corporation | Selective passive address resolution learning |
US20110258346A1 (en) * | 2008-06-27 | 2011-10-20 | Laith Said | Method and System for Link Aggregation |
US9473382B2 (en) * | 2008-06-27 | 2016-10-18 | Telefonaktiebolaget Lm Ericsson (Publ) | Method and system for link aggregation |
US20100074265A1 (en) * | 2008-09-19 | 2010-03-25 | Oki Electronic Industry Co., Ltd. | Packet synchronization switching method and gateway device |
US9401878B2 (en) * | 2008-09-19 | 2016-07-26 | Oki Electric Industry Co., Ltd. | Packet synchronization switching method and gateway device |
US9276690B2 (en) * | 2009-09-02 | 2016-03-01 | Zte Corporation | Distributed electrical cross device, and system and method thereof for implementing sub-network connection (SNC) cascade protection |
US20120163796A1 (en) * | 2009-09-02 | 2012-06-28 | Zte Corporation | Distributed electrical cross device, and system and method thereof for implementing sub-network connection (snc) cascade protection |
WO2011026324A1 (en) * | 2009-09-02 | 2011-03-10 | 中兴通讯股份有限公司 | Distributed electrical cross device, and system and method thereof for implementing sub-network connection (snc) cascade protection |
US8654630B2 (en) | 2010-03-19 | 2014-02-18 | Brocade Communications Systems, Inc. | Techniques for link redundancy in layer 2 networks |
CN101980488A (en) * | 2010-10-22 | 2011-02-23 | 中兴通讯股份有限公司 | Address resolution protocol (ARP) table entry management method and three-layer exchanger |
US8902734B2 (en) * | 2011-01-31 | 2014-12-02 | Telefonaktiebolaget L M Ericsson (Publ) | System and method for providing communication connection resilience |
US20120195189A1 (en) * | 2011-01-31 | 2012-08-02 | Dawei Wang | System and method for providing communication connection resilience |
Also Published As
Publication number | Publication date |
---|---|
EP1425881A2 (en) | 2004-06-09 |
WO2003024029A3 (en) | 2003-07-31 |
US20030048501A1 (en) | 2003-03-13 |
US8031589B2 (en) | 2011-10-04 |
US20050180339A1 (en) | 2005-08-18 |
WO2003024029A2 (en) | 2003-03-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US8031589B2 (en) | Metropolitan area local access service system | |
US10237634B2 (en) | Method of processing traffic in a node in a transport network with a network controller | |
US7660238B2 (en) | Mesh with protection channel access (MPCA) | |
US6532088B1 (en) | System and method for packet level distributed routing in fiber optic rings | |
US7606886B1 (en) | Method and system for providing operations, administration, and maintenance capabilities in packet over optics networks | |
US7315511B2 (en) | Transmitter, SONET/SDH transmitter, and transmission system | |
US7649847B2 (en) | Architectures for evolving traditional service provider networks and methods of optimization therefor | |
EP1302035B1 (en) | Joint IP/optical layer restoration after a routewr failure | |
US7606224B2 (en) | Transmission apparatus for making ring switching at SONET/SDH and RPR levels | |
US7170851B1 (en) | Systems and methods for automatic topology provisioning for SONET networks | |
US7002907B1 (en) | System and methods for automatic equipment provisioning for SONET networks | |
US20040109408A1 (en) | Fast protection for TDM and data services | |
WO2004010653A1 (en) | Metropolitan area local access service system | |
EP2472778A1 (en) | Method for time division multiplex service protection | |
US20060062246A1 (en) | Multi-service transport apparatus for integrated transport networks | |
EP1435153B1 (en) | Metropolitan area local access service system | |
EP1246408B1 (en) | Mapping of data frames from a local area network into a synchronous digital telecommunications system | |
Cisco | Overview | |
Cisco | Overview | |
Cisco | Cisco ONS 15454 SDH Product Overview, Release 3.3 | |
Jones et al. | Sprint long distance network survivability: today and tomorrow | |
Lam et al. | Optical Ethernet: Protocols, management, and 1–100 G technologies | |
Alegria et al. | The WaveStar™ BandWidth Manager: The key building block in the next-generation transport network | |
Graber et al. | Multi-service switches and the Service Intelligent™ optical architecture for SONET/SDH metro networks | |
Hamad | Performance analysis and management of RPR (resilient packet ring) rings attached to an new large layer 2 (L2) networks (NLL2N) |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SILICON VALLEY BANK, CALIFORNIA Free format text: SECURITY INTEREST;ASSIGNOR:ONFIBER COMMUNICATIONS, INC.;REEL/FRAME:014514/0548 Effective date: 20030815 |
|
AS | Assignment |
Owner name: ONFIBER COMMUNICATIONS, INC., TEXAS Free format text: RELEASE;ASSIGNOR:SILICON VALLEY BANK;REEL/FRAME:017093/0859 Effective date: 20050925 |
|
AS | Assignment |
Owner name: QWEST COMMUNICATIONS INTERNATIONAL INC., COLORADO Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ONFIBER COMMUNICATIONS, INC.;REEL/FRAME:019781/0759 Effective date: 20070830 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |