CFM Message Forwarding in PBB-TE Networks
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Solution Overview
Problem
The existing Connectivity Fault Management (CFM) mechanisms for traditional Ethernet are not applicable to Provider Backbone Bridge Traffic Engineering (PBB-TE) networks, as they rely on destination addresses and VLAN IDs for path identification, leading to issues with message forwarding and reply transmission in PBB-TE networks, where bidirectional paths have different identifiers and unknown messages are discarded.
Innovation Solution
A method and system for transmitting and processing CFM messages in PBB-TE networks, where a receiving node determines whether the connection maintenance target address matches its own address, and if not, forwards the message based on the path identifier, ensuring correct forwarding and reply transmission by encapsulating return path information in message headers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Ethernet CFM mechanisms use destination addresses and VLAN IDs for path identification, then message forwarding works in traditional Ethernet, but message forwarding fails in PBB-TE networks where bidirectional paths have different identifiers
Solution Approach 1:
The patent changes the addressing parameters from traditional Ethernet destination address and VLAN ID to PBB-TE specific path identifier and connection maintenance target address. This parameter change enables CFM messages to be correctly identified and forwarded in PBB-TE networks where bidirectional paths have different identifiers, resolving the incompatibility between traditional Ethernet CFM mechanisms and PBB-TE network architecture
Solution Approach 2:
The patent introduces an intermediary addressing mechanism using path identifiers that act as mediators between the CFM messages and the PBB-TE network forwarding plane. This intermediary layer enables proper message routing by translating CFM message requirements into PBB-TE forwarding table lookups, allowing seamless operation across the network boundary
2Productivity
If PBB-TE networks discard unknown messages instead of broadcasting, then network efficiency is improved, but CFM message delivery to all MEPs fails
Solution Approach 1:
The patent makes the path identifier universal by using it for both unicast CFM message forwarding and multicast delivery to all MEPs in a maintenance association. This multi-functionality allows a single addressing mechanism to serve both efficiency-oriented unicast routing and reliability-oriented multicast delivery, eliminating the need for separate broadcasting mechanisms in PBB-TE networks
3Device complexity
If CFM messages are forwarded based on destination address in traditional Ethernet, then simple forwarding is achieved, but reply transmission fails in PBB-TE where bidirectional paths have different identifiers
Solution Approach 1:
The patent segments the forwarding process into two independent stages: first, forward the CFM message to the connection maintenance target address using the path identifier; second, forward the reply message back to the source using the return path identifier. This segmentation allows each stage to use simple address-based forwarding while the overall system handles bidirectional path complexity, maintaining both simplicity and reliability
Data Source
AI summary
A method for transmitting a Connectivity Fault Management (CFM) message of Ethernet includes: receiving a CFM message transmitted from a source node, the CFM message including identifier of a path and a connection maintenance target address; determining whether the connection maintenance target address matches address of a receiving node, and if yes, terminating the CFM message; otherwise forwarding the CFM message to a next hop based upon the path identifier of the path. Another method and a system for transmitting a CFM message of Ethernet, a node for transmitting a CFM message of Ethernet, and a node for receiving a CFM message of Ethernet are also disclosed. With the invention, a CFM message may be forwarded according to information of a Medium Access Control (MAC) address and a Virtual Local Area Network Identifier (VLAN ID) of a path identifier where a monitored service is located, and thus may be forwarded correctly in a Provider Backbone Bridge Traffic Engineering (PBB-TE) network.