Multicast Convergence via Pre-advertised Join Messages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multilink networking environments, especially with Ethernet virtual private networks (EVPN), there is a challenge in efficiently managing multicast traffic across peer groups with multiple provider edge devices, leading to potential duplicate packets and increased convergence time during designated forwarder failures, as existing solutions require complex SMET route advertisements and replication table updates.
Innovation Solution
The solution involves allowing all peer devices in a peer group to advertise interest in multicast groups independently of their designated forwarder status, enabling them to receive and forward multicast packets, and simplifying the election process for a new designated forwarder by eliminating the need for SMET route advertisements and replication table updates, thus reducing convergence time and preventing duplicate packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If all peer devices advertise join messages for multicast groups, then multicast traffic convergence speed improves, but device complexity and message overhead increase
Solution Approach 1:
All peer devices pre-advertise join messages for multicast groups before actual multicast traffic arrives. This preliminary action ensures that when the designated forwarder fails and a new one is elected, the multicast traffic can immediately flow through the new designated forwarder without waiting for new join messages, thus achieving fast convergence while maintaining manageable device complexity through standardized pre-configuration
Solution Approach 2:
The patent makes all peer devices (not just the designated forwarder) capable of receiving and forwarding multicast traffic by having them all advertise join messages. This universal capability ensures that multicast traffic can be maintained through any peer device in the peer group, providing redundancy and fast failover while distributing the functionality across multiple devices rather than concentrating it in one
2Measurement precision
If SMET route advertisements and replication table updates are required during designated forwarder election, then routing accuracy is maintained, but convergence time increases
Solution Approach 1:
Join messages are advertised preliminarily before the designated forwarder election occurs. This means that when the election happens and a new designated forwarder is selected, the routing information is already in place, eliminating the need for time-consuming SMET route advertisements and replication table updates after the election, thus achieving both routing accuracy and fast convergence
Solution Approach 2:
Instead of updating routing information after the designated forwarder election (the conventional approach), the patent inverts the sequence by having all peer devices pre-advertise their join messages before the election occurs. This inversion eliminates the post-election routing update delay while maintaining routing accuracy, as the routing information is already established before the failover scenario unfolds
Data Source
AI summary
Peer devices in a peer group of provider edge devices to which a customer edge device is multi-homed, advertise Selective Multicast Ethernet Tag (SMET) routes to other peer devices on a core to receive traffic addressed to a multicast group. The peer devices in the peer group advertise the SMET routes irrespective of whether they are the designated forwarder or not. A peer device receiving traffic for the multicast group will drop the packet if it is not the designated forwarder and will forward the packet if it is the designated forwarder.