摘要:
For a survivable portion of a network, a backup port for a first router of the survivable network, to reach a destination node in the event of a single node failure, may be determined by (a) accepting a routing path graph having the destination node, wherein the routing path graph includes one or more links terminated by one or more primary ports of the first router; and (b) for each router of at least a part of the routing path graph, (1) assuming that the current router is removed, defining (A) a first part of the routing path graph including the destination node, and (B) a second part of the routing path graph separated from the first part wherein the second part defines one or more sub-graphs, and (2) determining the backup port for the first router by examining at least one of the one or more sub-graphs to find a link to the first part of the routing path graph.
摘要:
A router in a survivable portion of a network may forward packets to a destination node even in the event of a double-link failure. For a given destination node, the router has previously been configured with a primary port, a primary backup port, and a secondary backup port. The router receives a packet addressed to the destination node within the survivable portion of the network, wherein the packet includes information indicating that the packet has encountered a failure. The router then selects one of (A) the primary port, (B) the primary backup port and (C) the secondary backup port on which to forward the received packet, such that a backup path with no dead loops is defined. The router may obtain a recovery distance of at least one of (A) the primary backup port based on a backup path to which it leads, and (B) the secondary backup port based on a backup path to which it leads, and may further obtain counter information in a packet indicative of a failure distance. In this case, the router may select a port whose recovery distance is greater than the failure distance. The router may identify a pattern of the failure. In this case, the router may make its selection using a forwarding policy associated with the identified pattern.
摘要:
Backup ports for a first router of the survivable network are determined so that the first router can reach a destination node in the event of a double link failure. A routing path graph having the destination node is accepted. The routing path graph includes one or more links terminated by one or more primary ports of the first router. For each router of at least a part of the routing path graph, assuming that a link terminated by a primary port of the first router is removed, a first part of the routing path graph including the destination node and a second part of the routing path graph (sub-graph) separated from the first part are defined. Two exits for the sub-graph to reach the graph are determined. A primary backup port and a secondary backup port are determined for the first router using the determined two exits.
摘要:
For a survivable portion of a network, a backup port for a first router of the survivable network, to reach a destination node in the event of a single node failure, may be determined by (a) accepting a routing path graph having the destination node, wherein the routing path graph includes one or more links terminated by one or more primary ports of the first router; and (b) for each router of at least a part of the routing path graph, (1) assuming that the current router is removed, defining (A) a first part of the routing path graph including the destination node, and (B) a second part of the routing path graph separated from the first part wherein the second part defines one or more sub-graphs, and (2) determining the backup port for the first router by examining at least one of the one or more sub-graphs to find a link to the first part of the routing path graph.
摘要:
For a survivable portion of a network, a backup port for a first router of the survivable network, to reach a destination node in the event of a single link failure, may be determined by (a) accepting a routing path graph having the destination node, wherein the routing path graph includes one or more links terminated by one or more primary ports of the first router, and (b) for each router of at least a part of the routing path graph, (1) assuming that a link terminated by a primary port of the current router is removed, defining (A) a first part of the routing path graph including the destination node, and (B) a second part of the routing path graph separated from the first part wherein the second part defines a sub-graph, and (2) determining the backup port for the first router by examining the sub-graph with respect to the first part of the routing path graph.
摘要:
Backup ports for a first router of the survivable network are determined so that the first router can reach a destination node in the event of a double link failure. A routing path graph having the destination node is accepted. The routing path graph includes one or more links terminated by one or more primary ports of the first router. For each router of at least a part of the routing path graph, assuming that a link terminated by a primary port of the first router is removed, a first part of the routing path graph including the destination node and a second part of the routing path graph (sub-graph) separated from the first part are defined. Two exits for the sub-graph to reach the graph are determined. A primary backup port and a secondary backup port are determined for the first router using the determined two exits.
摘要:
A router in a survivable portion of a network may forward packets to a destination node even in the event of a double-link failure. For a given destination node, the router has previously been configured with a primary port, a primary backup port, and a secondary backup port. The router receives a packet addressed to the destination node within the survivable portion of the network, wherein the packet includes information indicating that the packet has encountered a failure. The router then selects one of (A) the primary port, (B) the primary backup port and (C) the secondary backup port on which to forward the received packet, such that a backup path with no dead loops is defined. The router may obtain a recovery distance of at least one of (A) the primary backup port based on a backup path to which it leads, and (B) the secondary backup port based on a backup path to which it leads, and may further obtain counter information in a packet indicative of a failure distance. In this case, the router may select a port whose recovery distance is greater than the failure distance. The router may identify a pattern of the failure. In this case, the router may make its selection using a forwarding policy associated with the identified pattern.
摘要:
A scheme to achieve fast recovery from SRLG failures in the IP layer is described. An exemplary scheme, called multi-section shortest path first (“MSSPF”), builds on the idea of IP Fast Reroute (“IPFRR”), guarantees 100% recovery of SRLG failures and causes no dead loops. Given a source node, a destination node, and a shared risk group failure on a next hop from the source node to the destination node, failure recovery information may be determined by (1) accepting a graph representing network topology information including the source node and the destination node, (2) determining a node which is able to reach the destination node using a route which does not include the source node, wherein a path from the source node to the determined node is not affected by the shared risk group failure, and (3) storing, in association with the shared risk group failure, both (i) a network address associated with the determined node and (ii) an alternative output port of the source node using the shortest path from the source node to the determined node.
摘要:
In one embodiment, the extrusion process can comprise: feeding a thermoplastic polycarbonate resin to an extruder; heating the resin to a temperature sufficient to attain a melt viscosity of less than or equal to about 300 Pa.s; extruding the heated resin; and passing the extruded resin through a gap between two solid metal calendering rolls to produce a film. The film has a birefringence of less than or equal to about 50 nm.
摘要:
A scheme to achieve fast recovery from SRLG failures in the IP layer is described. An exemplary scheme, called multi-section shortest path first (“MSSPF”), builds on the idea of IP Fast Reroute (“IPFRR”), guarantees 100% recovery of SRLG failures and causes no dead loops. Given a source node, a destination node, and a shared risk group failure on a next hop from the source node to the destination node, failure recovery information may be determined by (1) accepting a graph representing network topology information including the source node and the destination node, (2) determining a node which is able to reach the destination node using a route which does not include the source node, wherein a path from the source node to the determined node is not affected by the shared risk group failure, and (3) storing, in association with the shared risk group failure, both (i) a network address associated with the determined node and (ii) an alternative output port of the source node using the shortest path from the source node to the determined node.