Virtual links in a routed ethernet mesh network
Virtual links may be used to divert traffic within an Ethernet network without affecting overall traffic patterns on the Ethernet network. In one embodiment, the virtual link may be established on the network via a routing system in use on the network. Nodes on a defined path for the virtual link will install forwarding state for the virtual link so that traffic may follow the defined path through the network. The logical view of the virtual link, from a routing perspective however, has the same cost as the shortest path between the endpoints of the virtual link and, accordingly, does not affect other traffic patterns on the network. Once established, the end nodes on the virtual path will have two equal cost paths through the network—one following the shortest path tree and one along the path for the virtual link. The end nodes may use a tie breaking process in an Equal Cost Multi Path (ECMP) selection process to preferentially select the virtual link over the shortest path.
1. A method of using virtual links in a routed Ethernet mesh network, the method comprising the steps of:
receiving, by a node on the routed Ethernet mesh network, a routing system link state advertisement containing a virtual link description, which incorporates an explicit route object, the explicit route object defining a path for the virtual link through the routed Ethernet mesh network between two end points on the interior of the routed Ethernet mesh network, the virtual link description further specifying a list of dataplane identifiers to be associated with the virtual link on the network and administrative status;
wherein the virtual link is advertised as having a same cost metric as a shortest path between the two end points instead of its own cost metric such that other traffic patterns on the routed Ethernet mesh network are not disrupted; and
wherein an Equal Cost Multi Path (ECMP) tie breaking process is used to select between the virtual link and the shortest path between the two end points.
2. The method of claim 1 , the method further comprising the steps of determining, by the node, whether the node is on the path for the virtual link through the routed Ethernet mesh network.
3. The method of claim 2 , wherein if the node is on the path for the virtual link through the routed Ethernet mesh network, the method further comprising the step of installing a cross-connect for the dataplane identifiers.
4. The method of claim 1 , wherein the virtual link is a Traffic Engineered (TE) virtual link, and wherein the routing system link state advertisement advertising the TE virtual link further includes an explicit metric associated with the virtual link.
5. The method of claim 4 , further comprising installing, by the node, the TE virtual link in a network routing topology database as if it were a real link on the routed Ethernet mesh network.
6. The method of claim 4 , further comprising the step of implementing a handshake protocol to avoid loop formation.
7. The method of claim 1 , further comprising the step of implementing a handshake protocol to avoid loop formation.
8. The method of claim 7 , wherein the handshake protocol further conveys state information to enable the two end points to coordinate activation and deactivation of the virtual link.
9. An Ethernet node using virtual links in a routed Ethernet mesh network, the Ethernet node comprising:
an interface configured to receive a routing system link state advertisement containing a virtual link description, which incorporates an explicit route object, the explicit route object defining a path for the virtual link through the routed Ethernet mesh network between two end points on the interior of the routed Ethernet mesh network, the virtual link description further specifying a list of dataplane identifiers to be associated with the virtual link on the network and administrative status;
wherein the virtual link is advertised as having a same cost metric as a shortest path between the two end points instead of its own cost metric such that other traffic patterns on the routed Ethernet mesh network are not disrupted; and
wherein an Equal Cost Multi Path (ECMP) tie breaking process is used to select between the virtual link and the shortest path between the two end points.
10. The Ethernet node of claim 9 , wherein the Ethernet node is configured to determine whether the node is on the path for the virtual link through the routed Ethernet mesh network.
11. The Ethernet node of claim 10 , wherein if the Ethernet node is on the path for the virtual link through the routed Ethernet mesh network, the Ethernet node is configured to install a cross-connect for the dataplane identifiers.
12. The Ethernet node of claim 9 , wherein the virtual link is a Traffic Engineered (TE) virtual link, and wherein the routing system link state advertisement advertising the TE virtual link further includes an explicit metric associated with the virtual link.
13. The Ethernet node of claim 12 , wherein the Ethernet node is configured to install the TE virtual link in a network routing topology database as if it were a real link on the routed Ethernet mesh network.
14. The Ethernet node of claim 12 , wherein the Ethernet node is configured to implement a handshake protocol to avoid loop formation.
15. The Ethernet node of claim 9 , wherein the Ethernet node is configured to implement a handshake protocol to avoid loop formation.
16. The Ethernet node of claim 15 , wherein the handshake protocol further conveys state information to enable the two end points to coordinate activation and deactivation of the virtual link.