[openstack-dev] [ironic] the possible use of dhcp client id

Chuck Carlino chuckjcarlino at gmail.com
Wed Nov 12 22:38:57 UTC 2014


I'm working on the neutron side of a couple of ironic issues, and I need 
some help.  Here are the issues.

 1. If a nic on an ironic server fails and is replaced by a nic with a
    different mac address, neutron's dhcp service will not serve it the
    same ip address.  This can be worked around by deleting the neutron
    port and creating a new one, but it leaves a window wherein the ip
    address could be lost to an unrelated port creation happening at the
    same time.
 2. While performing large deployments, a random nic failure can cause
    the failure of the entire deploy.  The ability to retry a failed
    boot with a different nic has been requested.

It has been proposed that both issues could be at least partially 
addressed by adding the ability to use dhcp client id to neutron. In 
this solution, the dhcp client is configured to use a dhcp client id, 
and the server associates this client id (instead of mac address) with 
the ip address.  Note that this idea just came up today, so no code 
exists yet to try things out.

My questions:

For 1, the mac address of the neutron port will be left different from 
the actual nic's mac address.  Is that a problem for ironic? It makes me 
feel uneasy, and might confuse users, but that's all I got.

In general, does using dhcp client id present any issues for booting an 
ironic server?  I've done a bit of web searching and from a protocol 
perspective it looks feasible, but I don't get a sense of whether it's a 
good general solution.

If you have any off-the-top 'there's no chance that'll work' or better 
things to try kind of feedback, it would be great to hear it now since 
I'm about to start a POC to try it out.


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