Multicast traffic is dropped when Arista Switches are utilized in VMware NSX for vSphere 6.2

Products

• VMware NSX for vSphere

Issue/Introduction

Symptoms:
In VMware NSX for vSphere 6.2.x environments utilizing Arista physical switches, the following symptoms occur:

• All Broadcast, Unknown unicast, and Multicast (BUM) traffic is not working
• All multicast packets that arrives at the VXLAN Tunnel End Point (VTEP) are dropped
• The host drops any received multicast packets if the VXLAN UDP port is set to the default 8472 value

Environment

VMware NSX for vSphere 6.2.x

Cause

This issue occurs on all Arista 7150 products that are running version EOS 4.12

Note: Arista EOS-4.12.7.1 drops multicast packets through port 8472. EOS-4.14.2F forwards the traffic properly.

Resolution

This is a physical hardware/software behavior and not a Broadcom Software defect.

To resolve this issue:

1. Upgrade EOS to version 4.13.0 or later. For more information, see Arista Support.
2. Configure NSX to use a different UDP port using REST API, specifically to 4789 per the VXLAN specification.