RBridge Unicast LSP Transmission for TRILL Packet Storm Avoidance
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Solution Overview
Problem
In TRILL networks, the current ESADI protocol message transmission via multicast leads to packet storms when a new RBridge joins, overwhelming the network with LSP messages and causing CPU burden, potentially leading to equipment failure.
Innovation Solution
Implementing a method where an RBridge sends LSP messages to newly joining neighbors via unicast, with a delay duration determined by priority, reducing the number of messages and preventing simultaneous transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ESADI protocol uses multicast to distribute LSP messages throughout the TRILL network, then all RBridges can receive MAC information updates, but packet storms occur when new RBridges join causing network overload
Solution Approach 1:
The patent applies local quality by differentiating the message transmission approach based on the recipient's role and knowledge state. RBridges that already have the LSP message in their link state database receive it via multicast, while newly joining RBridges receive it via unicast from their designated neighbor. This localized differentiation eliminates the need for all RBridges to process every multicast message, reducing CPU burden while maintaining reliable MAC information distribution.
Solution Approach 2:
The patent segments the LSP message distribution process into two distinct paths: (1) multicast distribution for RBridges that should already have the message, and (2) unicast distribution to newly joining RBridges through designated neighbors. This segmentation prevents the amplification effect where every RBridge retransmits multicast messages, thereby avoiding packet storms while ensuring all RBridges eventually receive the MAC information updates.
2Loss of information
If a new ESADI RBridge sends LSP messages via multicast upon joining, then it can notify all network RBridges of its presence and MAC information, but this generates exponential message multiplication forming packet storms
Solution Approach 1:
The patent applies preliminary action by having RBridges maintain their link state database and know which LSP messages they already possess before new RBridges join. When a new RBridge joins, existing RBridges can determine whether to send LSP messages via unicast based on whether the new RBridge already has the message in its database. This preliminary knowledge prevents redundant message multiplication while ensuring complete MAC information propagation.
Solution Approach 2:
The patent introduces designated neighbors as intermediaries between new RBridges and the rest of the network. Instead of every RBridge directly multicasting LSP messages to all others, the designated neighbor acts as a mediator that receives LSP messages and selectively forwards them only to newly joining RBridges that need the information. This intermediary role dramatically reduces the total number of LSP messages while maintaining complete information propagation.
3Productivity
If the TRILL network maintains multiple paths for load balancing, then bandwidth utilization improves, but the complexity of managing MAC information across multiple paths increases
Solution Approach 1:
The patent merges the MAC information management function into a unified link state database that all RBridges share through the IS-IS routing protocol. Instead of each RBridge independently tracking MAC information across multiple paths, all MAC information is centralized in the link state database, and RBridges use their routing tables to determine the best paths. This merging approach maintains high bandwidth utilization through multiple paths while simplifying MAC information management through centralization.
Data Source
Figure 1~3
AI summary
A method and device for avoiding End Station Address Distribution Information (ESADI) protocol packet storms are provided, and the method includes: when an RBridge discovers a newly joining neighbor, the RBridge sends a Link State Protocol Data Unit (LSP) message to the neighbor by means of unicast. The method and device prevent the multicast storms from generating, avoid generating any major influence on the equipment, and enhance the stability and robustness of the equipment and the network.