Q-in-Q Ethernet rings

Inactive Publication Date: 2010-09-23
RPX CLEARINGHOUSE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007]An aspect of the present invention is to provide a simple, resilient and high-speed virtual ring for frame-based traffic such as Ethernet that redresses one or more of the deficiencies in the prior art as described above. The resilient virtual ring has a plurality of nodes interconnected by working and protection virtual paths. The virtual ring will have a working path in which traffic flows in one direction, and a protection path in which the traffic flows in the opposite direction. It is conceivable to have multiple virtual rings which have the same routing for the working path and for the protection paths. It is similarly possible to envision multiple virtual rings where the routing is a mirror image, the routing of one or more rings protection path corresponding to the routing of the working path or path of other rings. It is similarly possible to consider a node to simultaneously be a ring node on several topologically disjoint rings at the same time. Each virtual ring implements a unique Ethernet broadcast domain. Each virtual ring is implemented via configured connectivity for a set of VLANs. Traffic upon insertion into the ring is tagged using ring tags which serve to identify the originating station on the ring and are associated with the specific broadcast domain. These tags are removed when the traffic leaves the ring. For Ethernet, these ring tags are VLAN IDs (VIDS) and the insertion of VLAN tags is described in IEEE standard 802.1ad. When traffic enters the ring, the ingress node tags the traffic with a working-path VID which also identifies the entry point to the ring.

Problems solved by technology

Because of its “flood-and-learn” nature, standard Ethernet (IEEE 802.3) is generally unsuitable for network topologies where there is more than one path between any two nodes.
The existence of a parallel path creates a loop around which the Ethernet frames circle endlessly, thus overburdening the network.
Deployment of large (metro area) Ethernet rings is hindered, however, by the fact that Ethernet rings are prone to endlessly loop unless protocols such as IEEE 802.lD Spanning Tree Protocol (STP) or IEEE 802.1W Rapid Reconfiguration are used to detect and disable parallel branches that create loops.
While Spanning Tree Protocol and Rapid Reconfiguration can eliminate loops on Ethernet rings, these protocols introduce recovery lags in the order of tens of seconds, i.e. the time to recover from a fault in the ring is unacceptably high for customers who expect seamless connectivity and undetectable fault correction.
Thus, even if all the other components of the Ethernet switches are capable of handling higher rates, as is currently achievable, the ring MAC-PHY chip limits the overall bit-rate of the ring.

Method used

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Embodiment Construction

[0034]In general, and as will be elaborated below with respect to the specific embodiments illustrated in FIGS. 1-6, the present invention provides both a resilient, virtual ring for frame-based traffic such as, preferably, Ethernet as well as a method of routing frame-based (e.g. Ethernet) traffic over a resilient, virtual ring. Although the embodiments described below are implemented in Ethernet, it should be understood that the invention could be applied to other frame-based networks.

[0035]A resilient, virtual Ethernet ring designated generally by reference numeral 10 in FIG. 1A has a plurality of nodes (labelled A, B, C and D) interconnected by a working path 12 and a protection path 14 per ring node, FIG. 1A being an exemplar of a single instance of what would be replicated once per node on the ring. Each path being implemented via VLAN configuration (the blocking and unblocking of ports). As will be appreciated by those of ordinary skill in the art, the virtual ring can be vir...

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Abstract

A resilient virtual Ethernet ring has nodes interconnected by working and protection paths. Each node has a set of VLAN IDs (VIDs) for tagging traffic entering the ring by identifying the ingress node and whether the traffic is on the working or protection path. MAC addresses are learned in one direction around the ring. A port aliasing module records in a forwarding table a port direction opposite to a learned port direction. Each node can also cross-connect working and protection paths. If a span fails, the two nodes immediately on either side of the failure are cross-connected to fold the ring working-path traffic is cross-connected onto the protection path at the first of the two nodes and is then cross-connected back onto the working path at the second of the two nodes so that traffic always ingresses and egresses the ring from the working path.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This is the first application filed for the present invention.TECHNICAL FIELD[0002]The present invention relates generally to Ethernet and, in particular, to Ethernet rings for Metro Area Networks.BACKGROUND OF THE INVENTION[0003]Because of its “flood-and-learn” nature, standard Ethernet (IEEE 802.3) is generally unsuitable for network topologies where there is more than one path between any two nodes. The existence of a parallel path creates a loop around which the Ethernet frames circle endlessly, thus overburdening the network. Therefore, Ethernet is best suited to a tree topology rather than a ring. However, ring topologies are desirable for deploying Ethernet in Metro Area Networks where ring topologies are desirable, e.g. for resiliency.[0004]Deployment of large (metro area) Ethernet rings is hindered, however, by the fact that Ethernet rings are prone to endlessly loop unless protocols such as IEEE 802.lD Spanning Tree Protocol (ST...

Claims

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Application Information

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IPC IPC(8): H04L12/28H04L12/26
CPCH04L12/437H04L12/465H04L2012/421H04L41/0668H04L12/4641
InventorALLAN, DAVIDBRAGG, NIGELHOLNESS, MARC
OwnerRPX CLEARINGHOUSE