iDRAC DHCP offers cause installer to attempt to retrieve installation sources too early

[Dane Elwell]

When PXE booting the Ubuntu Jammy installer (22.04.2), dhclient sends DHCP requests on all interfaces, including the iDRAC interface. It seems to send the request over the iDRAC interface first and that returns a DHCP offer almost immediately.

The installer then attempts to netboot by downloading the ISO from our installer, but this fails, because it doesn't have an actual IP address yet.

Shortly after this failure, the actual NICs receive their DHCP offers and connect, but by this time, it's too late - the install has already failed.

This can all be seen on the attached screenshot.

Testing the connection from the initramfs prompt shows that the actual NICs have IP addresses and the ISO can be retrieved manually over the network with wget.

As a workaround, I can blacklist the cdc_ether kernel module to disable the iDRAC interface at boot time by adding the kernel option `modprobe.blacklist=cdc_ether` to the kernel command line.

I cannot see an option in the iDRAC 8 interface to disable the iDRAC interface, or disable it from responding to DHCP requests.

The installer should ignore iDRAC interfaces when making DHCP requests.

[Dane Elwell (dane-elwell)]

Server was a Dell PowerEdge 730XD.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Chris Schanzle (cschanzle)]

Happening to me with a PowerEdge R350 with updated firmware throughout. Thanks for the blacklist workaround, confirmed working with modprobe.blacklist=cdc_ether. Great find, Dane!