BGP-LS Pseudowire Propagation Across Administrative Systems
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Solution Overview
Problem
Conventional pseudowire systems face challenges in establishing and maintaining end-to-end connections across multiple Administrative Systems (ASs), with high route processor switchover convergence times and operational complexity, especially when using targeted label distribution protocol (LDP) or border gateway protocol (BGP), which are not always available or necessary, particularly with technologies like Segment Routing.
Innovation Solution
The solution involves using Border Gateway Protocol Link State (BGP-LS) messages to propagate pseudowire data across multiple ASs, enabling end-to-end pseudowire connections by modifying existing Interior Gateway Protocol (IGP) and BGP-LS messaging to support pseudowire data transmission between Provider Edge (PE) routers across different ASs, utilizing Network Layer Reachability Information (NLRI) that includes Type Length Values (TLVs) consistent with IPv4, IPv6, and OSPF/IS-IS protocols, and employing External Border Gateway Protocol (eBGP) peering and Route Reflectors for efficient data distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional pseudowire systems use targeted label distribution protocol (LDP) or border gateway protocol (BGP) for configuration, then pseudowire connections can be established within a single Administrative System, but the systems cannot support end-to-end pseudowire connections across multiple Administrative Systems
Solution Approach 1:
The patent segments the pseudowire configuration into two distinct protocol layers: LDP handles local pseudowire setup within an AS, while BGP-LS handles inter-AS pseudowire propagation. This segmentation allows each protocol to operate independently in its designated scope, enabling multi-AS connectivity without requiring a single protocol to handle all complexity.
Solution Approach 2:
BGP-LS acts as an intermediary between LDP and the inter-AS routing infrastructure. It receives pseudowire information from LDP within an AS and propagates it to PE routers in other ASs, mediating the transition from intra-AS to inter-AS pseudowire establishment without direct LDP communication between distant ASs.
2Reliability
If LDP is used for pseudowire configuration in high available systems, then pseudowire connections can be maintained, but route processor switchover convergence time becomes high
Solution Approach 1:
BGP-LS pre-establishes pseudowire information distribution paths across multiple ASs before actual pseudowire traffic needs to flow. PE routers receive and cache pseudowire information from BGP-LS in advance, so when a route processor switchover occurs, the convergence is faster because the pseudowire configuration data is already available locally rather than needing to be requested during the switchover.
3Adaptability or versatility
If conventional pseudowire systems use single-AS configuration protocols, then implementation is simpler, but they cannot support pseudowire links extending across two or more Administrative Systems
Solution Approach 1:
BGP-LS serves multiple functions: it propagates pseudowire information across AS boundaries, maintains synchronization between PE routers in different ASs, and works seamlessly with existing LDP-based intra-AS pseudowire establishment. This multi-functionality enables multi-AS support while reusing existing protocol infrastructure, thereby limiting the increase in operational complexity.
Data Source
AI summary
Servicing a pseudowire communication across multiple Administrative Systems (AS) by components of packet data networks. A first Provider Edge (PE) router of a first AS receives a first Interior Gateway Protocol (IGP) message from a source PE router of the first AS that includes pseudowire data. The first PE router creates a first Border Gateway Protocol Link State (BGP-LS) message that includes the pseudowire data and transmits the first BGP-LS message to a second PE router of a second AS and intended for a destination PE router of the second AS. The first PE router then receives a second BGP-LS message from the second PE router that includes modified pseudowire data. The first PE router creates a second IGP message that includes the modified pseudowire data and transmits the second IGP message to the source PE router.