Distinguishing Connectivity Verification from Forwarding Protocol Functionality
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Solution Overview
Problem
In computer networks, it is challenging for local network devices to determine whether a failure in connectivity verification protocols, such as BFD, is due to a non-responsive remote network device's connectivity verification protocol or a forwarding protocol failure, leading to improper traffic forwarding and network issues.
Innovation Solution
A local network device sends connectivity verification protocol echo messages to a remote network device, which are forwarded using the forwarding protocol, allowing the local device to determine if the forwarding protocol is functioning, thereby distinguishing between connectivity verification availability and forwarding protocol functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If connectivity verification protocols (BFD) are used for rapid failure detection, then failure detection speed is improved, but the ability to distinguish between protocol unavailability and forwarding protocol failure deteriorates
Solution Approach 1:
The patent segments the failure detection process into two independent phases: (1) connectivity verification protocol status detection using BFD control packets, and (2) forwarding protocol functionality detection using echo packets. This segmentation allows each phase to independently determine its specific aspect without interference, resolving the contradiction by enabling precise differentiation between protocol unavailability and forwarding failures.
Solution Approach 2:
The patent introduces echo packets as an intermediary mechanism to test forwarding protocol functionality. These echo packets act as a mediator that can traverse the forwarding plane independently of BFD control packets, allowing the local device to indirectly assess forwarding protocol status without disrupting the primary connectivity verification process.
2Reliability
If BFD sessions are established to monitor connectivity, then connectivity verification is improved, but network overhead increases
Solution Approach 1:
The patent applies partial action by using BFD echo packets only when needed to diagnose specific forwarding protocol failures, rather than continuously establishing full BFD sessions for all connectivity verification. This selective approach maintains reliability for critical failures while reducing overall network overhead by avoiding unnecessary protocol establishment attempts.
3Ease of operation
If local devices declare links as failed when BFD sessions cannot be established, then failure detection is simplified, but network reliability deteriorates due to improper traffic forwarding
Solution Approach 1:
The patent implements a feedback mechanism where the local device sends echo packets and analyzes the responses to determine the actual cause of BFD session failure. Based on this feedback, the device can accurately distinguish between temporary protocol unavailability (where traffic forwarding should continue) and genuine forwarding failures (where traffic routing should be changed), thereby maintaining both operational simplicity and network reliability.
Data Source
AI summary
In one embodiment, a local network device transmits a connectivity verification protocol control message over a link to a remote network device to attempt to establish a connectivity verification protocol session with the remote network device. In response to non-receipt of a returned connectivity verification protocol control message from the remote network device, the local network device determines that there is an inability to establish a connectivity verification protocol session with the remote network device. The local network device then sends a connectivity verification protocol echo message over the link to the remote network device without establishment of a connectivity verification protocol session. The echo message is sent using a forwarding protocol. In response to receipt of a reply to the connectivity verification protocol echo message from the remote network device, the local network device determines that the forwarding protocol is functioning and uses the link to forward data traffic to the remote network device.