BIER Fast Reroute with Bit Indexed Routing Table Backup Entries
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Solution Overview
Problem
Traditional multicast systems face challenges with high computational resource usage and unnecessary packet delivery due to complex control plane information management, leading to performance limitations and inefficiencies in network scalability and bandwidth utilization.
Innovation Solution
The implementation of Bit Indexed Explicit Replication (BIER) with fast reroute capability, which reduces state information by attaching receiver information to packets as bits and using bit positions for forwarding, eliminating the need for multicast distribution trees and per-group state information at each node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional multicast systems are used, then packet delivery to multiple receivers is achieved, but control plane information management becomes complex and consumes high computational resources
Solution Approach 1:
The patent extracts the receiver identification information from the control plane and embeds it directly into the packet header as a bit string. This removes the need for complex control plane state information at each router, as the receiver information is now self-contained in the packet itself, enabling stateless multicast forwarding.
Solution Approach 2:
The patent changes the representation of receiver information from traditional multicast group addresses and distribution trees to a compact bit string format. Each bit position in the string corresponds to a specific egress router or receiver group, allowing efficient indexing and forwarding decisions without complex control plane state.
2Adaptability or versatility
If traditional multicast distribution trees are maintained, then packet forwarding to multiple destinations is enabled, but per-group state information at each node increases memory and processing requirements
Solution Approach 1:
The patent removes the need for per-group state information at intermediate routers by extracting all necessary forwarding information into the packet header. The bit string in the header contains all receiver identification information needed for forwarding decisions, eliminating the need for routers to maintain per-multicast-group state tables.
Solution Approach 2:
The packet itself carries all the information needed for its own forwarding through the network. The bit string in the packet header serves as a self-contained forwarding instruction set that enables each router to make forwarding decisions without consulting external control plane state,实现ing stateless multicast.
3Reliability
If fast reroute capability is added to BIER, then traffic loss during failures is minimized, but forwarding table complexity increases
Solution Approach 1:
The patent pre-computes and stores backup next-hop information in the forwarding table alongside primary next-hop entries. When a link or node failure is detected, the router can immediately switch to the pre-computed backup path without requiring complex real-time recalculations, thus minimizing traffic loss while maintaining a relatively simple forwarding table structure.
Data Source
AI summary
Methods, devices and program instructions are disclosed for performing bit indexed explicit replication (BIER) including fast reroute capability. One embodiment of a method includes receiving, from an egress node of a BIER network, an advertisement at a forwarding node, where the advertisement identifies a mapping of the egress node to a bit position of a packet bit string to be carried by a packet through the network. The embodiment further includes generating or updating a primary entry for the egress node in a bit indexed routing table (BIRT) for the forwarding node, and determining whether a backup entry for the egress node is to be included in the BIRT. In response to a determination that a backup entry is to be included, the embodiment further includes generating or updating the backup entry in the BIRT.