EVPN VRF gateways do not consistently exchange routes over Inter-SR BGP

Products

• VMware NSX

Issue/Introduction

While NSX v4.2.1 introduced the capability of enabling Inter-SR routing on VRF gateways, the feature does not function in EVPN VRF gateways, or if the EVPN VRFs learn ISR> routes those routes unexpectedly disappear from a VRF during BGP updates or later routing reconfigurations.

Environment

VMware NSX 4.2.1 and later

Cause

EVPN and inter-SR are incompatible features, for both Single-site or Multi-site topologies. Inter-SR is meant for IPv4/IPv6 routes directly learned in the T0/VRF, this applies to Static/connected/distributed for IGP/BGP learned within that VRF/T0 through IPv4/IPv6 unicast address family. As a result, Type 5 routes and most other routes learned from the MP-BGP in EVPN should not be expected to propagate reliably, if at all, over Inter-SR routing.

Resolution

There is currently no workaround for this limitation. Compatibility support for Inter-SR routing with EVPN VRFs is planned to be added in future versions of NSX.

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