Overlay Multicast Roaming With Pre-Stored Tunnel Join State
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Solution Overview
Problem
In overlay networks, the transition of multicast traffic from a roaming source to a new network device incurs delays and results in traffic loss due to the need for the requesting network device to detect and send a new network join request, causing disruptions during the transition process.
Innovation Solution
Maintaining a multicast state in the control plane of network devices and programming forwarding hardware entries based on this state, allowing the new source network device to immediately start forwarding multicast traffic via tunnels without waiting for a network join request.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the requesting network device waits for a new network join request to be sent and processed after source roaming, then the network protocol can be maintained, but transition delays occur and traffic loss results
Solution Approach 1:
The patent applies preliminary action by having the requesting network device proactively send a network join request to the new source network device before the source actually roams. This preemptive join request is stored in the control plane, so when the source does roam, the forwarding hardware can immediately use the pre-stored join request information to forward traffic without waiting for a new request to be processed, thereby eliminating transition delays and preventing traffic loss.
2Adaptability or versatility
If the requesting network device sends a new network join request after detecting source roaming, then the multicast state can be updated, but traffic loss occurs during the transition process
Solution Approach 1:
The system performs preliminary action by pre-storing the network join request in the control plane before the source roaming occurs. When roaming happens, the forwarding hardware immediately retrieves the pre-stored join request information and programs the necessary forwarding entries, allowing traffic to be forwarded without interruption and preventing traffic loss during the transition.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining the multicast state in the control plane and using pre-stored join request information to continue forwarding traffic seamlessly. The system keeps the useful action of multicast traffic forwarding continuous by having the forwarding hardware immediately switch to the new source network device using pre-prepared information, eliminating gaps in traffic delivery.
3Device complexity
If the network device uses traditional multicast routing protocols, then the protocol simplicity is maintained, but transition delays and traffic loss occur during source roaming
Solution Approach 1:
The patent applies preliminary action by having the requesting network device send and store the network join request in advance. This pre-stored information is then used by the forwarding hardware to immediately forward traffic when the source roams, significantly improving traffic delivery efficiency without requiring complex protocol changes or additional processing during the actual transition.
Data Source
AI summary
A first network device operating as a tunnel endpoint in a tunnel fabric is provided. During operation, the first network device can receive, via a local port, a network join request to receive multicast traffic of a multicast group from a second network device. The first network device can store a multicast state for the multicast group in a data structure associated with the control plane. The multicast state can indicate that the network join request is received via a tunnel between the first and second network devices. The first network device can then determine whether a source of the multicast group is coupled to the first network device. If the source is coupled to the first network device, it can program a multicast forwarding entry corresponding to the multicast state in forwarding hardware and forward the multicast traffic to the second network device based on the multicast forwarding entry.