Liaison VRF Reachability Validation Using EVI TLV OAM Ping
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Solution Overview
Problem
Existing OAM ping mechanisms cannot validate the reachability of a liaison VRF during the provisioning of a new EVPN, as they rely on overlay tunnels and IP addresses, which are not available when the EVPN has not commenced communication with external networks.
Innovation Solution
A new type of TLV, the EVPN Instance Identifier (EVI) TLV, is encapsulated in an OAM ping packet, allowing validation of the liaison VRF configuration by mapping it to an EVI value, even before tunnels are formed with other EVPN devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing OAM ping mechanisms are used to validate liaison VRF, then validation can be performed after tunnel formation, but validation cannot be performed before tunnel formation when EVPN is newly provisioned
Solution Approach 1:
The patent applies preliminary action by enabling OAM ping validation to occur before overlay tunnel formation. The EVI TLV is processed directly by the border router without requiring tunnel establishment first, allowing configuration validation to happen in advance during the provisioning phase, thus eliminating the waiting period for tunnel formation.
Solution Approach 2:
The patent extracts the tunnel formation requirement from the validation process. By using EVI TLV that can be processed directly by the border router, the solution separates the validation function from the tunnel establishment prerequisite, allowing validation to proceed independently of tunnel state.
2Ease of operation
If overlay tunnels are required for OAM ping to reach liaison VRF, then existing mechanisms work for established EVPN, but they fail when liaison VRF has not formed tunnels with other EVPN devices
Solution Approach 1:
The patent applies universality by creating a validation mechanism that functions in both established and newly provisioned EVPN scenarios. The EVI TLV approach allows the same OAM ping mechanism to work whether tunnels exist or not, making the validation process universally applicable across different EVPN states without requiring separate procedures.
3Reliability
If IP addresses are not configured on liaison VRF, then liaison VRF can act as pure liaison, but existing OAM ping mechanisms cannot reach liaison VRF
Solution Approach 1:
The patent uses EVI TLV as an intermediary to enable reachability validation without requiring IP address configuration on the liaison VRF. The EVI TLV carries the EVPN instance identifier that allows the border router to identify and respond to OAM ping packets, serving as a mediator between the validation mechanism and the liaison VRF configuration.
Data Source
AI summary
Systems and methods provide a new type of time-length-value data stream (TLV) which can be encapsulated in an OAM ping packet. This “EVI TLV” encapsulating OAM ping packet can be sent to a network device (e.g., a border router) that a liaison VRF is provisioned on. Upon receipt, the encapsulated EVI TLV instructs the network device to determine whether the configuration of the liaison VRF is mapped to an EVI value specified by the EVI TLV. If the configuration of the liaison VRF is mapped to the specified EVI value, the network device returns an echo response indicating that the configuration of the liaison VRF is mapped onto the specified EVI value. Such a response may indicate that the liaison VRF is reachable for the EVPN.