Virtual Node Ingress Protection for Multipoint LSPs
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Solution Overview
Problem
Existing multipoint Label Switched Paths (LSPs) in computer networks face significant downtime and slow service restoration when the root node fails, particularly in multicast applications like IP television, due to the need to tear down and reestablish the entire LSP with a new forwarding equivalence class.
Innovation Solution
Implementing a virtual node as a root node that remains constant across primary and backup ingress nodes, allowing traffic to be rerouted along a backup path within the same multipoint LSP without reestablishing the entire path, using virtual node identifiers and pre-established tunnels for rapid convergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire multipoint LSP is torn down and reestablished after a root node failure, then the network can maintain accurate routing information, but the service restoration time becomes unacceptably long for multicast applications
Solution Approach 1:
The patent segments the multipoint LSP into two independent parts: the downstream segment from egress nodes to the merge point (which remains intact) and the upstream segment from the root node to the merge point (which is reestablished). This segmentation allows the downstream segment to continue functioning during failure recovery, enabling fast service restoration without complete LSP teardown while maintaining routing accuracy through separate FEC management for each segment.
2Measurement precision
If a new FEC is created based on the new root node address, then the routing information remains accurate, but the convergence time increases due to complete LSP reestablishment
Solution Approach 1:
The patent divides the FEC management into two segments: the downstream FEC identifier (based on egress node and merge point) remains unchanged and continues to identify the downstream segment, while only the upstream FEC (based on root node address) needs to be updated. This segmentation allows routing information to remain accurate for the downstream segment while enabling fast convergence by avoiding complete FEC reestablishment.
Solution Approach 2:
The patent performs preliminary actions by pre-establishing backup root nodes and maintaining their FEC information in advance. When a root node failure occurs, the backup root node can immediately take over using pre-configured FEC information, eliminating the need for complete LSP reestablishment and enabling rapid convergence while maintaining routing accuracy.
3Stability of the object's composition
If the multipoint LSP is completely reestablished, then network topology changes are accurately reflected, but network bandwidth is wasted during the reestablishment process
Solution Approach 1:
The patent segments the LSP reestablishment process to only rebuild the upstream segment from the new root node to the merge point, while the downstream segment from the merge point to egress nodes remains active and continues to carry traffic. This segmentation accurately reflects network topology changes in the upstream segment while preserving bandwidth-efficient traffic flow through the intact downstream segment, avoiding complete LSP teardown and reestablishment.
Data Source
AI summary
Techniques include providing ingress protection for multipoint label switched paths (LSPs). According to the techniques, a primary ingress node and a backup ingress node of a network are both configured to advertise a virtual node identifier of a virtual node as a next hop for a multicast source. Two or more egress nodes of the network then use the virtual node as a root node reachable through the primary ingress node to establish a multipoint LSP. After the multipoint LSP is established, the primary ingress node forwards traffic of the multicast source on the multipoint LSP. When failure occurs at the primary ingress node, the backup ingress node forwards the traffic of the multicast source along a backup path and onto the same multipoint LSP with the virtual node as the root node reachable through the backup ingress node. The techniques enable ingress protection without tearing down the multipoint LSP.