Bug ID 577863: DHCP relay not forwarding server DHCPOFFER and DHCPACK message after some time

Last Modified: Oct 01, 2018

Bug Tracker

Affected Product:  See more info
BIG-IP PEM(all modules)

Known Affected Versions:
11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4, 11.6.0 HF5, 11.6.0 HF6, 11.6.0 HF7, 11.6.0 HF8, 11.6.1, 12.0.0, 12.0.0 HF1, 12.0.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2

Fixed In:
13.0.0, 12.1.2, 11.6.1 HF1

Opened: Mar 03, 2016
Severity: 3-Major
Related AskF5 Article:
K56504204

Symptoms

If the routing table on the DHCP server is misconfigured, so that the DHCP server knows how to send packets to the BIG-IP self IP address (used by the BIG-IP system DHCP relay), but does not know how to send packets to DHCP clients, DHCP clients will not receive a DHCP reply for unicast requests and will start to broadcast DHCP renewal. After a while, the BIG-IP system will stop relaying DHCPOFFER and DHCPACK back to DHCP clients altogether.

Impact

The BIG-IP system stops relaying DHCPOFFER and DHCPACK back to DHCP clients.

Conditions

DHCP server unicast reply back to client is not received by client, causing DHCP client to send broadcast DHCP packets (with client's IP address as the source IP address).

Workaround

Modify the DHCP server routing table, so that the DHCP server can deliver DHCP reply packets back to clients successfully.

Fix Information

DHCP relay now continues forwarding the server DHCPOFFER and DHCPACK messages under these conditions.

Behavior Change