MPLS Multicast Path Encoding Without Per-Flow Router State
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Solution Overview
Problem
Existing multicast communication systems in MPLS networks are stateful, requiring each router along the multicast distribution tree to maintain states in both the control and data planes, which can lead to inefficiencies and complexity.
Innovation Solution
Implementing stateless multicast communications in MPLS networks using local label spaces and network-wide unique node identifiers to encode an explicit path tree, allowing routers to uniquely identify nodes and adjacencies through tuples, and using label stacks to forward packets efficiently without maintaining per-flow states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stateful multicast is implemented in MPLS networks, then multicast communication can be supported, but each router must maintain per-flow states in control and data planes, increasing device complexity
Solution Approach 1:
The patent extracts the state maintenance requirement from individual routers by introducing a centralized controller that computes and distributes segment routing policies. This removes the burden of per-flow state maintenance from data plane routers, resolving the contradiction between supporting multicast and reducing device complexity
Solution Approach 2:
The patent introduces a centralized controller as an intermediary between the control plane and data plane. This mediator computes the explicit path trees and distributes segment routing policies to routers, enabling multicast support without requiring routers to maintain complex per-flow states
2Device complexity
If local label spaces are used for encoding explicit path trees, then label conflicts between different nodes are avoided, but unique node identification across the network is required
Solution Approach 1:
The patent segments the global label space into local label spaces assigned to different nodes. Each node uses its own local label space for encoding segments, which eliminates label conflicts while maintaining unique identifiability through the combination of node identifier and local labels
Solution Approach 2:
The patent adds a node identifier dimension to the label encoding scheme. By combining the node identifier (first dimension) with local labels (second dimension), the system achieves both local label space independence and global node distinguishability
3Reliability
If per-flow states are maintained at each router, then multicast distribution can be controlled, but network scalability is limited
Solution Approach 1:
The patent extracts state maintenance from individual routers and centralizes it in the control plane. The data plane routers only need to maintain segment routing forwarding tables based on distributed policies, not per-flow states, enabling network scalability while preserving multicast distribution control
Solution Approach 2:
The patent uses segment routing policies as templates that are copied and distributed to multiple routers. Instead of maintaining unique per-flow states at each router, the same policy templates are replicated, reducing state complexity while maintaining control over multicast distribution
Data Source
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AI summary
Various example embodiments for supporting stateless multicast communications in a communication system are presented. Various example embodiments for supporting stateless multicast communications may be configured to support stateless multicast communications in a label switching network (e.g., a Multiprotocol Label Switching (MPLS) network, an MPLS - Traffic Engineered (TE) network, or the like) based on use of local label spaces of nodes of the label switching network for encoding of an explicit path tree for the multicast communications within the multicast communications. Various example embodiments for supporting stateless multicast communications in a label switching network based on use of local label spaces of nodes of the label switching network may be configured to support use of local label spaces of nodes of the label switching network by using network-wide unique node identifiers to uniquely identify nodes with which the node and adjacency labels of the explicit path tree are associated.