[openstack-dev] [neutron] high dhcp lease times in neutron deployments considered harmful (or not???)

Vishvananda Ishaya vishvananda at gmail.com
Wed Jan 28 17:43:36 UTC 2015

On Jan 28, 2015, at 9:36 AM, Carl Baldwin <carl at ecbaldwin.net> wrote:

> On Wed, Jan 28, 2015 at 9:52 AM, Salvatore Orlando <sorlando at nicira.com> wrote:
>> The patch Kevin points out increased the lease to 24 hours (which I agree is
>> as arbitrary as 2 minutes, 8 minutes, or 1 century) because it introduced
>> use of DHCPRELEASE message in the agent, which is supported by dnsmasq (to
>> the best of my knowledge) and is functionally similar to FORCERENEW.
> My understanding was that the dhcp release mechanism in dnsmasq does
> not actually unicast a FORCERENEW message to the client.  Does it?  I
> thought it just released dnsmasq's record of the lease.  If I'm right,
> this is a huge difference.  It is a big pain knowing that there are
> many clients out there who may not renew their leases to get updated
> dhcp options for hours and hours.  I don't think there is a reliable
> way for the server to force renew to the client, is there?  Do clients
> support the FORCERENEW unicast message?

If you are using the dhcp-release script (that we got included in ubuntu years
ago for nova-network), it sends a release packet on behalf of the client so
that dnsmasq can update its leases table, but it doesn’t send any message to
the client to tell it to update.


> Carl
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