Cross-AS BIER Route Updates Using BGP Path Attributes
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Solution Overview
Problem
Existing technologies face challenges in efficiently exchanging BIER information across autonomous systems, limiting effective multicast packet forwarding between different BIER domains.
Innovation Solution
A method and apparatus for exchanging BIER information across autonomous systems by using a route notifying mechanism that includes collecting BFR IDs and notifying a route UPDATE message with NLRI and BIER Path Attribute, enabling BIFT forwarding entries to be added in network devices, facilitating BIER route notification between ASs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing route notifying mechanisms are used, then route information can be exchanged between autonomous systems, but BIER information cannot be effectively exchanged across autonomous systems
Solution Approach 1:
The patent extends the BGP UPDATE message format by adding a new Path Attribute type (type 271) specifically for carrying BIER information. This parameter change allows the existing BGP protocol to transport new types of routing information (BIER paths, BFR-IDs, forwarding bit masks) without requiring a completely new protocol, thus enabling BIER information exchange across autonomous systems while maintaining protocol compatibility
Solution Approach 2:
The patent introduces ASBRs (Autonomous System Border Routers) as intermediary devices that perform BIER route summarization and translation between different autonomous systems. These ASBRs collect BIER information from internal BFRs, summarize it into condensed route entries with forwarding bit masks, and advertise them to external autonomous systems via extended BGP updates, thereby enabling efficient cross-AS BIER information exchange
2Loss of information
If detailed BIER information is advertised across autonomous systems, then complete routing information is available, but message size and processing complexity increase
Solution Approach 1:
The patent segments BIER information into two distinct components: (1) BFR-IDs that identify egress routers, and (2) forwarding bit masks (F-BMs) that encode the paths to reach those egress routers. This segmentation allows the routing information to be structured in a compact format where multiple BFRs can be represented efficiently using bit mask operations, reducing the overall information size while maintaining completeness
Solution Approach 2:
The patent performs BIER route summarization in advance at the ASBR before advertising routes to external autonomous systems. The ASBR pre-computes forwarding bit masks that represent aggregated paths to multiple BFRs, condensing what would otherwise be numerous detailed route entries into fewer summarized entries. This preliminary summarization reduces the volume of information that needs to be processed and exchanged between autonomous systems
Data Source
AI summary
The present disclosure provides route notifying methods and electronic devices. In an embodiment, a first ASBR in a first AS carries an NLRI as well as a newly-added BIER Path Attribute in a UPDATE message and notifies them to a second AS. BIER information in the autonomous system is exchanged between the ASs in a cross-AS BIER scenario, and BIER route notifying between the ASs in the cross-AS BIER scenario is realized.