DHCP relay TTL limitation for VMC on AWS

Products

• VMware Cloud on AWS

Issue/Introduction

Symptoms:
When configuring DHCP relay agents on distributed logical router in NSX for vSphere, you experience these symptoms:

• Virtual machines configured on Logical Switches where a DHCP relay agent is configured do not obtain IP addresses.
• The DHCP server does not receive any initial DHCP discovery packets from the relay agent.
• DHCP discovery packets are dropped in transit due to TTL expiry.

Cause

Distributed logical router sets an IP TTL (time to live) of 10 for forwarded DHCP requests from relay agents. If your DHCP server is 10 or more hops away, the TTL will expire in transit and the DHCP discovery packets gets dropped.

Resolution

Currently no resolution please see workaround below

Workaround:
Use third party DHCP relay or reduce network hops to below 10 between VMC and DHCP server.