NSX host TEP (vmk) interfaces do not receive dynamic IPs from DHCP Server

Products

• VMware NSX

Issue/Introduction

• NSX host TEP (vmk) interfaces are configured to use DHCP for IP assignment.
• NSX host TEP interfaces do not receive dynamic IPs from DHCP Server.
• NSX overlay network connectivity is down for the affected host.
• NSX host log /var/log/dhclient.log confirms that TEP (vmk) DHCP client discover message is sent but no DHCP server offer is received.
• Packet captures on the host vmnics being used by the TEP (vmk) interfaces also confirm that that DHCP client discover message is sent but no DHCP server offer is received.
• This behviour persists with manually created vmk interfaces.

Environment

VMware NSX-T Data Center

VMware NSX

VMware vSphere ESXi

Cause

The above behaviour indicates that the the TEP (vmk) client interface sends a DHCP discover message to find available DHCP servers and request an IP address.  However, no DHCP offer message is received back from the DHCP server or relay.

 

Resolution

This is a condition that may occur in a VMware NSX environment.

Additional Information

Related KBs:  ESXi VMkernel Interfaces vmk10/vmk11 Fallback to APIPA Causing NSX VTEP Failure and Troubleshooting NSX Using Packet Captures

 

To determine a root a cause for this issue, it may be helpful to investigate further using steps similar to the below:

1. Confirm if DHCP discover message is received by the DHCP server.
2. Confirm if DHCP offer message is sent by the DHCP server.
3. Determine where on datapath that the DHCP offer message is failing.