Bi-directional Segment Routing via Association Identifiers
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Solution Overview
Problem
Segment routing networks lack the ability to establish bi-directional paths, as they do not maintain per LSP state during transit or at endpoints, making it difficult to recognize incoming SR policies and create bi-directional LSPs.
Innovation Solution
The use of association identifiers, such as association labels or association segment identifiers, to bind two uni-directional SR policies in an SR network, allowing correlation of incoming and outgoing SR policies and enabling bi-directional LSPs by encoding these identifiers in packet headers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If segment routing networks use source routing paradigm without per LSP state maintenance, then routing flexibility and simplicity are improved, but the ability to establish bi-directional paths deteriorates
Solution Approach 1:
The patent introduces association identifiers (such as association labels or association segment identifiers) as intermediary elements to bind two unidirectional SR policies together. These identifiers act as mediators that enable nodes to recognize and correlate incoming and outgoing SR policies, thereby establishing bi-directional LSPs without requiring per-LSP state maintenance throughout the network. The association identifier is encoded in packet headers to facilitate this binding mechanism.
2Reliability
If association identifiers are encoded in packet headers to bind SR policies, then bi-directional LSP capability is improved, but packet header complexity increases
Solution Approach 1:
The patent embeds the association identifier within the existing packet header structure, specifically within the segment routing header. The association identifier is nested as an additional field that can be integrated with existing header components such as the segment list or routing information. This nesting approach allows bi-directional LSP capability to be added without fundamentally redesigning the packet header, thereby minimizing the increase in header complexity while still achieving the desired bi-directional path establishment.
Data Source
AI summary
Techniques for implementing bi-directional paths in a segment routing communication network are described. A first segment routing policy, including a first path from a first node in the communication network to a second node in the communication network, is installed. A second segment routing policy, including a second path from the second node to the first node in the communication network, is installed. At the first node, a first identifier associated with the first segment routing policy is bound to a second association identifier associated with the second segment routing policy. At the second node, a second identifier associated with the second segment routing policy is bound to a first association identifier associated with the first segment routing policy.