Segment Routing P2MP Paths Using Multicast SIDs Without State
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Solution Overview
Problem
Existing network communication technologies face scalability issues due to the need for maintaining path states, which consume memory and processing resources, especially when creating point-to-multipoint (P2MP) paths, as stateless segment routing (SR) protocols do not support P2MP paths effectively.
Innovation Solution
Implementing a segment routing mechanism that uses multicast segment identifiers (SIDs) to describe P2MP paths within an IPv6 network, allowing nodes to forward packets without maintaining states, by encapsulating packets with segment lists that include multicast SIDs indicating branches and nodes, enabling stateless P2MP communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If network states are used to route network packets in P2MP paths, then path routing functionality is achieved, but memory and processing resources increase and scalability is limited
Solution Approach 1:
The P2MP path is segmented into a sequence of SIDs (Segment Identifiers) that describe the path segments. Each SID represents a specific segment or hop in the P2MP tree, allowing the path to be broken down into manageable units that can be processed without maintaining complete path states at each node.
Solution Approach 2:
The path state information is extracted from the core network nodes and concentrated at the root node. The segment list containing all path information is pushed onto packets at the root, removing the need for intermediate nodes to maintain path states while preserving routing functionality.
2Adaptability or versatility
If forwarding tables are expanded to support more paths, then network connectivity increases, but processing resources and search time increase
Solution Approach 1:
The complete path information is prepared in advance as a segment list at the root node before packets are forwarded. This preliminary action eliminates the need for intermediate nodes to search forwarding tables, as the path is already determined and encoded in the packet's segment list.
Solution Approach 2:
The segment list is copied onto each packet at the root node, creating a self-contained routing instruction set that travels with the packet throughout its journey. This copying mechanism eliminates the need for intermediate nodes to access external forwarding tables, improving processing efficiency.
3Adaptability or versatility
If stateful routing protocols are used for P2MP paths, then path establishment is achieved, but state maintenance complexity increases
Solution Approach 1:
State maintenance is extracted from intermediate and leaf nodes and concentrated exclusively at the root node. The root node maintains the P2MP path state and generates segment lists, while other nodes simply forward packets based on the segment information contained in each packet without maintaining any path state.
Solution Approach 2:
Each packet carries its own routing instructions in the form of a segment list, making the packet self-sufficient for routing decisions. Intermediate nodes do not need to maintain path state or make routing decisions based on stored information; they simply process the segment list already present in the packet.
Data Source
AI summary
Disclosed is a mechanism implemented by an ingress node in a network. The mechanism comprises receiving, at a receiver of the ingress node, a packet. A segment list describing a segment routing point-to-multipoint (SR P2MP) path is pushed onto the packet. The packet is transmitted on a downstream interface along the SR P2MP path.