BIER Fast Reroute Using Enhanced BIFT Backup Paths
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Solution Overview
Problem
There is currently no architecture for supporting Bit Index Explicit Replication (BIER) fast re-route (BIER-FRR) to handle network failures such as node or link failures effectively.
Innovation Solution
The development of enhanced bit index forwarding tables (BIFTe) that provide fast rerouting by building on existing bit index forwarding tables (BIFT) to handle network failures, utilizing IP loop-free alternates (LFAs) and BIER network topologies to create backup paths for packet forwarding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional BIFT is used for packet forwarding in BIER domains, then packet routing is simple and efficient, but the system cannot handle network failures such as node or link failures
Solution Approach 1:
The patent pre-computes backup next-hop addresses and backup forwarding bit masks for potential failure scenarios before actual failures occur. The enhanced BIFT stores multiple next-hop addresses (primary and backup) and multiple forwarding bit masks (primary and backup) for each destination BFER, enabling immediate switchover upon failure without real-time computation
Solution Approach 2:
The patent segments the forwarding information by separating primary and backup forwarding paths into distinct entries within the enhanced BIFT. Each destination BFER has independent primary and backup next-hop addresses and forwarding bit masks, allowing selective activation of backup paths without affecting primary forwarding operations
2Speed
If backup paths are pre-computed and stored in enhanced BIFT, then fast rerouting is enabled upon failure, but memory and processing resources are consumed
Solution Approach 1:
The enhanced BIFT structure serves multiple functions: it maintains primary forwarding paths for normal operation, stores backup paths for failure scenarios, and provides a unified forwarding table that works for both normal and failure conditions. This eliminates the need for separate backup table structures
Solution Approach 2:
The patent computes and stores backup forwarding information only for critical failure scenarios rather than all possible failures. The backup next-hop addresses and forwarding bit masks are maintained for each destination BFER, providing sufficient protection without exhaustive redundancy
Data Source
AI summary
A method implemented by a network node in a BIER domain includes obtaining, by a control plane of the network node, an IP LFA from a FIB or RIB through a first interface, using, by the control plane of the network node, the IP LFA to build a BIFTe when the IP LFA is an expected type, accessing, by the control plane of the network node, a BIER network topology in an LSDB through a second interface, computing an LFA of the expected type, and using the LFA to build the BIFTe when the IP LFA is not of the expected type, updating, by the control plane of the network node, the BIFTe in a data plane of the network node through a third interface; and forwarding, by the data plane of the network node, BIER packets using the BIFTe to avoid a failure.