eBGP peers are treated as ECMP even though they have different MED

Products

• VMware NSX

Issue/Introduction

• Tier-0 gateway receives the same route from multiple eBGP peers that have different ASNs and the same AS-path length.
• The gateway also has “Multipath Relax” configured as enabled.
• The gateway treats the paths as ECMP even though the eBGP peers have different MED.

Environment

VMware NSX

VMware NSX-T

Cause

The behavior is as designed.

NSX does not compare MED from eBGP peers that have different ASNs and the same AS-path length.

No equivalent of bgp always-compare-med is available on NSX.

Resolution

To prefer one route to another, configure either workaround.

1. Configure AS PATH Prepend on the BGP peers.
2. Configure weight or local preference in the inbound route-map.
   If weight is the same. local preference is compared.