Hybrid Multicast Routing Protocol for Scalable Flow Tracking
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Solution Overview
Problem
Current multicast routing protocols, such as PIM-ASM and PIM-SSM, face scalability issues due to limitations in Ternary Content Addressable Memory (TCAM) space on hardware, and PIM-Bidir mode lacks (S, G) based tracking, making it cumbersome for flow-based troubleshooting.
Innovation Solution
Implementing a hybrid mode that combines PIM-Bidir on Last Hop Routers (LHRs) with shared tree Reverse-Path Forwarding and (S, G) states for traffic tracking, while maintaining only (*, G) states on other routers, allowing for improved scalability and tracking capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PIM-ASM or PIM-SSM protocols are used for multicast routing, then flow-based tracking capability is improved, but scalability is worsened due to TCAM space limitations
Solution Approach 1:
The patent applies local quality by implementing different multicast routing modes in different network locations. Specifically, PIM-ASM or PIM-SSM modes are implemented only on last-hop routers (LHRs) where flow-based tracking is needed, while other routers use PIM-Bidir mode. This localized implementation provides tracking capability exactly where required without imposing the scalability burden across the entire network.
2Productivity
If PIM-Bidir mode is used for multicast routing, then scalability is improved, but flow-based tracking capability is worsened due to lack of (S, G) based tracking
Solution Approach 1:
The patent implements local quality by strategically placing source-specific state maintenance only at last-hop routers where tracking is necessary. Upstream routers maintain only shared-tree states for scalability, while LHRs maintain both shared-tree and source-specific states to enable flow-based tracking and troubleshooting.
3Measurement precision
If source-specific states are maintained on all routers, then flow-based tracking capability is improved, but device complexity is worsened due to increased memory and processing requirements
Solution Approach 1:
The patent applies local quality by concentrating source-specific state maintenance exclusively at last-hop routers rather than distributing it across all routers. This localized approach enables flow-based tracking capability while minimizing the overall memory and processing requirements in the network, as only the necessary LHRs maintain these states.
Data Source
AI summary
Hybrid mode multicast routing may be provided. A switching device may receive a first join. Next, in response to receiving the first join, states for a first protocol mode (e.g., (S, G)) that is source aware and state for a second protocol mode (e.g., (*, G)) that is not source aware may be programed. Then a second join may be sent based on the states associated with the second protocol mode (e.g., (*, G)).