DHCP server ignores directed DHCPREQUEST on renewal

David W. Hankins David_Hankins at isc.org
Mon May 8 20:52:04 UTC 2006

On Sat, May 06, 2006 at 08:08:59AM -0700, Vladislav Belogrudov wrote:
> I try to test dchpd with provided dhclient.
> The procedure (discover,lease renewal) works fine
> but with some minor drawbacks. When the client wants
> to renew lease it sends unicast message to dchpd
> several times and dhcpd ignores it. Then client
> starts broadcasting request and gets acknowledgement.
> I wonder why server ignores first renewal requests..

Is it possible that the client's request is being delivered via an
interface other than eth0 on the dhcp server?

> I found that such directed DHCPREQUEST messages are
> ignored by the server in fallback_discard()

The fallback interface discards everything it receives - it is only
used to transmit unicast messages (broadcasts go via the LPF sockets,
and we could do unicasts there too, but we'd have to build our own
routing table, arp, etc...).

David W. Hankins		"If you don't do it right the first time,
Software Engineer			you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins

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