Multicast RSVP Fast Reroute Neighbor Identification
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Solution Overview
Problem
In multicast RSVP fast reroute (FRR) scenarios, there are challenges in correctly identifying the Point of Local Repair (PLR) that transmitted a backup RSVP Path message and the Merge Point (MP) that transmitted a backup RSVP Resv message due to multiple upstream or downstream neighbor routers, leading to potential timeouts and traffic disruption.
Innovation Solution
The PLR sets the SENDER_TEMPLATE object of backup Path messages to include the outgoing interface IP address on the primary path, and the PLR associates downstream neighbor backup interface IP addresses with primary interface IP addresses to uniquely identify the MP using the HOP and FILTER_SPEC objects in backup Resv messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the PLR uses standard RSVP FRR signaling without modifications, then the signaling process is simple, but the PLR and MP cannot be uniquely identified when multiple upstream or downstream neighbor routers exist
Solution Approach 1:
The patent modifies specific fields (SENDER_TEMPLATE and HOP objects) in the RSVP signaling messages to contain locally relevant identification information. The SENDER_TEMPLATE object includes the primary path outgoing interface IP address of the PLR, while the HOP object includes the backup path outgoing interface IP address. This local differentiation enables unique identification of PLR and MP without requiring global changes to the RSVP protocol structure.
2Reliability
If the PLR associates backup interface IP addresses with primary interface IP addresses, then neighbor router identification becomes accurate, but the processing complexity increases
Solution Approach 1:
The patent performs preliminary association between backup interface IP addresses and primary interface IP addresses before fast reroute activation. The PLR pre-establishes mappings between its primary path outgoing interface addresses and backup path outgoing interface addresses, and similarly associates downstream neighbor routers' backup interfaces with their primary interfaces. This preliminary preparation enables rapid and accurate identification during failure scenarios without complex real-time processing.
3Adaptability or versatility
If existing RFCs are leveraged for identification, then protocol compatibility is maintained, but identification accuracy may be insufficient in complex topologies
Solution Approach 1:
The patent changes the parameter values within existing RSVP message fields rather than introducing new message types or protocol structures. Specifically, it modifies the IP address values in the SENDER_TEMPLATE object and HOP object to encode identification information. This approach maintains compatibility with existing RFCs while providing sufficient identification accuracy for complex network topologies by utilizing the flexibility of existing parameter fields.
Data Source
AI summary
Techniques for performing neighbor router identification in the context of multicast RSVP fast reroute. In one set of embodiments, these techniques enable a Merge Point (MP) to correctly identify a Point of Local Repair (PLR) that transmitted a backup RSVP Path message in the scenario where the MP has multiple upstream neighbor routers. In another set of embodiments, these techniques enable a PLR to correctly identify an MP that transmitted a backup RSVP Resv message in the scenario where the PLR has multiple downstream neighbor routers.