NSX ESXi transport node disconnect after configuring Remote L3SPAN

Products

• VMware NSX

Issue/Introduction

• Remote L3SPAN is configured with the same port as mirror source (SRC) and destination (DST) at the same time.
• High packet rate and network bandwidth utilization is observed.
• vCenter Server reports Host disconnects.

Environment

• VMware NSX-T Data Center 3.x
• VMware NSX 4.x
• VCF 9.x

Cause

This issue occurs because L3SPAN is configured with one port as a mirror source and destination at the same time.

For example, L3SPAN is configured to use a LS as mirror SRC, and one of the ports of the same segment as mirror DST (the port's IP). In this case, when the mirror DST receives the mirrored packet, it mirrors the packet back again and again, which will cause the traffic loop and high rate of traffic.

Resolution

Configuring one port as mirror SRC and DST at the same time is a misconfiguration. Broadcom recommends to not configure this.

Before configuring IPv6 as mirror destination IP in L3SPAN, please use IP Discovery profile with IPv6 snooping enabled on the segment of mirror source ports configured in L3SPAN. This would allow it to check whether the port is configured as mirror source and destination at the same time.