Multicast Datapath Verification via Echo Request Messages
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Solution Overview
Problem
Current methods for verifying multicast connectivity, such as RFC 6450, cannot trace the hop-by-hop route for a multicast datapath, and vendor-proprietary tools lack true datapath OAM functionality as they do not send OAM packets along the normal IP multicast path.
Innovation Solution
A method and router device for verifying a multicast datapath by generating and sending multicast echo request and reply messages, which include identifiers and indications of responding routers, allowing routers to determine their role and send replies along the multicast tree, enabling hop-by-hop route tracing and connectivity verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If RFC 6450 is used for multicast connectivity verification, then the advantage is that multicast routers do not need to support extra OAM mechanisms, but the disadvantage is that it cannot trace the hop-by-hop route for a multicast datapath
Solution Approach 1:
The patent introduces a multicast echo request message as an intermediary OAM packet that traverses the multicast datapath. This message contains identifiers and is forwarded by routers along the multicast tree, enabling route tracing without requiring complex additional OAM mechanisms on each router. The echo request acts as a mediator that carries routing information back to the source for analysis.
Solution Approach 2:
The patent implements a feedback mechanism where routers along the multicast path send echo reply messages back to the initiating router. These replies contain information about the router's identity and position in the multicast tree, providing feedback that enables complete hop-by-hop route tracing. The feedback loop allows the source to reconstruct the entire datapath.
2Loss of information
If vendor-proprietary tools are used to show incoming and outgoing interfaces of a multicast router, then interface information can be displayed, but the tools are not true datapath OAM tools because no OAM packets traverse along the datapath as normal IP multicast packets
Solution Approach 1:
The patent enables routers to self-verify their participation in the multicast datapath by processing echo request messages. Each router automatically determines whether it belongs to the indicated responding routers and generates appropriate echo reply messages. This self-service mechanism ensures that only routers actually on the datapath can confirm their presence, providing reliable verification.
Solution Approach 2:
The echo request and reply messages serve as intermediaries that actually traverse the multicast datapath like normal IP multicast packets. Unlike vendor tools that only query local router states, these OAM packets physically travel along the datapath, interacting with each router to verify its participation and collect routing information.
3Adaptability or versatility
If a multicast echo request message includes an indication of responding routers, then selective verification is enabled, but the message processing complexity increases at each router
Solution Approach 1:
The patent segments the multicast datapath verification into discrete router nodes that can be individually identified and targeted. The echo request message contains indications of specific responding routers, allowing the verification process to be segmented into targeted interactions with individual routers rather than requiring all routers to process all verification messages. This reduces overall processing complexity.
Solution Approach 2:
The initiating router performs preliminary action by pre-configuring the echo request message with identifiers and indications of responding routers before sending it into the network. This preliminary setup allows downstream routers to quickly determine whether they need to respond or simply forward the message, reducing processing complexity at each node while maintaining selective verification capability.
Data Source
AI summary
The method includes at an initiating router generating a multicast echo request message that at least includes an identifier of a multicast tree and an indication of at least one responding router that should respond to the multicast echo request message; and sending the multicast echo request message to a downstream router of the initiating router along the multicast datapath of the multicast tree.