Shortest path bridging in a multi-area network

摘要

A method that improves multi-area routed Ethernet network design, in which multipath implementation in each of the areas is independent of each other area to allow optimal network design in each area. The network implements a shortest path bridging medium access control (SPBM) protocol. The areas include a Level 2 (L2) routing area coupled to a Level 1 (L1) routing area via multiple area border bridges (ABBs). The L1 routing area including a backbone edge bridge (BEB) coupled to the ABBs via multiple L1 multipath instances identified by respective backbone VLAN identifiers (B-VIDs). The ABBs receive an advertisement from the BEB that indicates a set of BEB identifiers, each of which identifies the BEB and is associated with a respective B-VID. Each of the BEB identifiers is unique. The ABBs also advertise into the L2 routing area, and translate the B-VIDs based on service identifiers for frames transiting the ABBs.

主权项

1. A method performed by an area border bridge (ABB) in a routed Ethernet network that comprises multiple routing areas, wherein multipath implementation in each of the areas is independent of each other area to allow optimal network design in each of the areas, the network implementing a shortest path bridging medium access control (SPBM) protocol for sending frames across the areas, wherein the areas include a Level 2 (L2) routing area coupled to a Level 1 (L1) routing area via a plurality of ABBs, the L1 routing area including a backbone edge bridge (BEB) coupled to the ABBs via a plurality of L1 multipath instances that are identified by respective L1 backbone VLAN identifiers (B-VIDs), and wherein each L1 multipath instance provides the shortest path from the BEB to a virtualized node representing the L2 routing area by transiting a respective one of the plurality of ABBs, the method comprising the steps of:
receiving, by the ABBs, an advertisement from the BEB that indicates a set of BEB identifiers, each of which identifies the BEB and is associated with a respective one of the L1 B-VIDs, wherein each BEB identifier is unique, and wherein the advertisement further indicates that a given one of the BEB identifiers is associated with a given L1 B-VID and a service identifier, the given L1 B-VID identifying a given one of the L1 multipath instances that transits into the L2 routing area via a transit ABB; advertising, by the transit ABB, into the L2 routing area, indicating that the given BEB identifier is associated with the service identifier and an L2 B-VID identifying an L2 multipath instance, to thereby allow frames destined for the BEB via the given L1 multipath instance to be forwarded to the transit ABB, wherein the given BEB identifier is advertised only by the transit ABB among the plurality of ABBs; translating, by the transit ABB based on the service identifier, the given L1 B-VID into the L2 B-VID for data frames that transit from the L1 routing area to the L2 routing area; and translating, by the transit ABB based on the service identifier, the L2 B-VID into the given L1 B-VID for data frames that transit from the L2 routing area to the L1 routing area; and the method which is enhanced to permit reassignment of services to different multipath instances without loss of frames, comprising further the steps of: setting, by a management system, receivers of a service in a given one of the routing areas to listen to advertisements of a B-VID A and advertisements of a B-VID B, wherein each of B-VID A and B-VID B identifies a multipath instance in the given routing area; setting by the management system transmitters of the service in the given routing area to transmit on both multipath instances identified by the B-VID A and the B-VID B, with the B-VID A being active and the B-VID B being in standby; setting the transmitters of the service in the given routing area to transmit on both multipath instances identified by the B-VID A and the B-VID B, with the B-VID B being active and the B-VID A being in standby; causing the ABBs through which the service is transmitted to update their translation tables to indicate that the service has migrated to the B-VID B in the given routing area; and removing all instances of the B-VID A associated with the service to thereby complete migration of the service from the B-VID A to the B-VID B.