Ingress Replication for Segment Routing Migration
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Solution Overview
Problem
In computer networks, especially during migration from RSVP to Segment Routing (SR) protocols, network devices such as PE routers may not know which devices are SR aware, leading to issues in establishing appropriate tunnels for multicast traffic, resulting in some routers being unable to receive multicast traffic.
Innovation Solution
Ingress PE routers determine the SR awareness of egress PE routers using BGP extended community attributes or static policies, and initiate the establishment of SR tunnels for SR-capable routers and non-SR tunnels for unaware routers, ensuring multicast traffic delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the network uses a mix of SR-aware and non-SR devices during migration, then network compatibility is improved, but tunnel establishment complexity increases
Solution Approach 1:
The network is segmented into SR-aware and non-SR device groups, with separate tunnel establishment procedures for each segment. The ingress router divides the egress router list into two categories and applies different tunnel setup methods accordingly, resolving the complexity of unified tunnel management across heterogeneous devices
Solution Approach 2:
The tunnel establishment process becomes dynamic based on the capabilities of egress routers. The ingress router adaptively selects between SR and non-SR tunnel protocols by checking the SR-capable flag in BGP routes, allowing the network to flexibly handle mixed device environments during migration
2Reliability
If SR tunnels are established to all egress routers, then multicast traffic delivery is improved, but resource waste increases due to unused tunnels
Solution Approach 1:
The ingress router performs preliminary classification of egress routers into SR-capable and non-SR categories before establishing tunnels. By checking the SR-capable flag in advance and creating only the appropriate tunnel types, the system avoids wasting resources on establishing unnecessary SR tunnels to non-SR devices while ensuring all devices receive multicast traffic
3Productivity
If the network migrates to SR protocol, then network modernization is improved, but interoperability with legacy systems deteriorates
Solution Approach 1:
Different parts of the network are assigned different protocol qualities based on their capabilities. SR tunnels are used where both endpoints are SR-aware, while non-SR tunnels are used for legacy devices. This local differentiation allows the network to modernize with SR where possible while maintaining interoperability with legacy systems where needed
Data Source
AI summary
In some examples, a network device may determine whether a first egress network device is segment routing (SR) aware. Based on the first egress network device being SR aware, the network device may initiate establishment of an SR tunnel toward the first egress network device. The network device may forward multicast traffic on the SR tunnel. The network device may also determine whether a second egress network device is SR aware. Based on the second egress network device not being segment routing aware, the network device may initiate establishment of a non-SR tunnel toward the second egress network device. The network device may forward multicast traffic on the non-SR tunnel.