PIM requirement for NSX T0 uplink interface for E/W multicast IGMP querying

Products

• VMware NSX

Issue/Introduction

The purpose is to inform the user that there is an inconsistency of requirements between configuring Tier-0 Gateways in A/A and A/S.
When the user re-configures the Tier-0 Gateway from A/S to A/A, PIM needs to be enabled on the Tier-0 uplink explicitly for E-W traffic to work.

• When NSX Edge Node are configured in Active/Active (A/A), East-West (E-W) Multicast traffic works only when Protocol Independent Multicast (PIM) is enabled on at least one Uplink on a Tier-0 gateway.
• • If a Tier-0 gateway has multiple uplinks and PIM is enabled on one uplink then E-W Multicast traffic will be forwarded.
• When NSX Edge Nodes are configured in Active/Standby (A/S), East-West Multicast works irrespective of PIM is enabled or not on Tier-0 uplink.
• A Rendezvous point (RP) configuration is not required for E-W Multicast traffic, but an RP is required for North-South (N-S) Multicast traffic.

Environment

3.x
4.x

Cause

This issue occurs when the gateway is in A/A mode and PIM is not configured on the gateway.

Resolution

This issue is resolved in VMware NSX 4.2.0

From VMware NSX 4.2.0 onwards, PIM is required to be enabled on at least one Tier-0 uplink, for multicast (E-W, N-S, S-N) to work in A/A and A/S Tier-0.

Workaround:

• Enable PIM on Tier-0 Gateway uplink when Tier-0 Gateway is configured as A/A to resolve the E-W multicast traffic issue.
  Please NSX-T administration guide for more details on how to configure Multicast.
• Alternatively if traffic is strictly Layer 2 turning off multicast within NSX can also alleviate intermittent traffic connectivity