System and method for restoration in a multimedia IP network
Disclosed herein are systems, methods, and computer readable media for modifying IP backbone link weights such that multicast traffic and unicast traffic will not travel on a same path between nodes. The method comprises assigning link weights to nodes within an IP backbone such that multicast forwarding paths and unicast forwarding paths are failure disjoint, and delivering undelivered multicast packets using IP unicast encapsulation to the loopback address of next hop router on a multicast tree upon link/interface failure.
1. A method of modifying IP backbone link weights such that multicast traffic and unicast traffic will travel on disjoint paths between nodes, the method comprising:
assigning link weights to nodes within an IP backbone such that multicast forwarding paths and unicast forwarding paths are failure disjoint to yield assigned link weights, wherein the IP backbone is an undirected network graph that is at least 2-connected; and
delivering undelivered multicast packets using IP unicast encapsulation to a next hop router on a multicast tree upon network failure, and wherein the assigned link weights are determined by:
(a) starting from a source node, locating a series of network links that form a ring;
(b) initializing a graph as nodes and links of the ring;
(c) initializing weights along one direction of the ring as high cost and in another direction as low cost; and
(d) iteratively adding links without weights to the graph by finding a series of links that form a chain whose endpoints terminate at the graph, wherein unidirectional links in one direction have a high cost and unidirectional links in another direction have a low cost, until all links are assigned weights.
2. The method of claim 1 , wherein multicast packets are assigned a higher forwarding priority.
3. The method of claim 1 , wherein encapsulated unicast packets are assigned a lower forwarding priority.
4. A system for modifying IP backbone link weights such that multicast traffic and unicast traffic will not travel on a same link along the same direction between nodes, the system comprising:
a first module configured to control a processor to assign link weights to nodes within an IP backbone such that multicast forwarding paths and unicast forwarding paths are failure disjoint to yield assigned link weights, wherein the IP backbone is an undirected network graph that is at least 2-connected; and
a second module configured to deliver undelivered multicast packets using IP unicast encapsulation to a next hop router on a multicast tree upon link failure, and wherein the assigned link weights are determined by:
(a) starting from a source node, locating a series of network links that form a ring;
(b) initializing a graph as nodes and links of the ring;
(c) initializing weights along one direction of the ring as high cost and another direction as low cost; and
(d) iteratively adding links without weights to the graph by finding a series of links that form a chain whose endpoints terminate at the graph, wherein unidirectional links in one direction have a high cost and unidirectional links in another direction have a low cost, until all links are assigned weights.
5. The system of claim 4 , wherein multicast packets are assigned a higher forwarding priority.
6. The system of claim 4 , wherein encapsulated unicast packets are assigned a lower forwarding priority.
7. A non-transitory computer-readable medium storing a computer program having instructions for modifying IP backbone link weights such that multicast traffic and unicast traffic will not travel on a same path between nodes, the instructions comprising:
assigning link weights to nodes within an IP backbone such that multicast forwarding paths and unicast forwarding paths are failure disjoint to yield assigned link weights, wherein the IP backbone is an undirected network graph that is at least 2-connected; and
delivering undelivered multicast packets using IP unicast encapsulation to a next hop router on a multicast tree upon link failure, and wherein the assigned link weights are determined by:
(a) starting from a source node, locating a series of network links that form a ring;
(b) initializing a graph as nodes and links of the ring;
(c) initializing weights along one direction of the ring as high cost and another direction as low cost; and
(d) iteratively adding links without weights to the graph by finding a series of links that form a chain whose endpoints terminate at the graph, wherein unidirectional links in one direction have a high cost and unidirectional links in another direction have a low cost, until all links are assigned weights.
8. The non-transitory computer-readable medium of claim 7 , wherein multicast packets are assigned a higher forwarding priority.
9. The non-transitory computer-readable medium of claim 7 , wherein encapsulated unicast packets are assigned a lower forwarding priority.