Host TEP interfaces fail to receive DHCP IP addresses - NSX
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Host TEP interfaces fail to receive DHCP IP addresses - NSX

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Article ID: 412992

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Updated On:

Products

VMware NSX

Issue/Introduction

  • Host TEP (vmk) interfaces show an IP address of 0.0.0.0 or a 169.254.x.x APIPA address.

  • Overlay connectivity is lost for the affected Transport Node.

  • Log file /var/log/dhclient.log confirms DHCPDISCOVER messages are sent but no DHCPOFFER is received.

  • Asymmetric behavior may be observed where the TEP acquires an IP on one vmnic but fails when failed over to the alternate uplink.

Environment

  • VMware NSX

  • VMware vSphere ESXi

Cause

  • Upstream physical network infrastructure (firewalls, DHCP relays, or switch port configurations) is blocking or failing to process BOOTP/DHCP requests.

  • This is often isolated to specific physical uplinks or VLAN trunking configurations.

Resolution

  1. Verify the DHCP process using packet captures on the affected host: pktcap-uw --uplink --capture UplinkSndKernel,UplinkRcvKernel --ip --udpport 67 -o - | tcpdump-uw -ner -

  2. Review the output to confirm if DHCPDISCOVER packets leave the host without a corresponding DHCPOFFER returning.

  3. Coordinate with the network team to ensure UDP ports 67 and 68 are permitted across the data path.

  4. Verify that DHCP Relay (IP Helper) is correctly configured for the TEP VLAN on the physical switches.

  5. As a best practice to prevent environmental DHCP outages, migrate TEP assignment from DHCP to a Static IP Pool. See Create an IP Pool for Tunnel Endpoint IP Addresses.

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.

To speak to a Technical Support Engineer, see KB 206567 - Contact Broadcom support

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