NSX-T T1 dhcp relay is not forwarding DHCPNAK packets to the client.

Products

• VMware NSX

Issue/Introduction

The Tier-1 gateway does not forward the DHCPNAK packet to the client, causing the client to repeatedly send DHCP requests in an attempt to retain its previous IP address. Eventually, the process times out due to the lack of response.

Environment

VMware NSX-T Data Center

Cause

When the DHCP relay is configured on the Tier-1 DR, it relays the DHCPNAK message. Since this is a NAK (Negative Acknowledgement) message, the yiaddr field is set to 0.0.0.0, indicating that no IP address is assigned to the client. The DHCP relay uses 0.0.0.0 as the destination IP when forwarding the reply to the client, which results in the packet being routed via the default route on the DR.

Resolution

This issue is resolved in NSX-T Data Center 3.1.3 and 3.0.3.2, available at Broadcom downloads.
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