FW: DHCPDECLINE messages question

[Dennis Dufford]

> On Fri, Sep 29, 2006 at 04:19:07PM -0400, Dennis Dufford wrote:
> > Sep 18 12:46:48 hw1ns2 dhcpd: [ID 702911 local7.info] DHCPREQUEST for 172.28.41.179 (172.28.198.20) from 00:11:43:42:b7:b2 (AMOOREXP) via 172.28.41.12
> > Sep 18 12:46:48 hw1ns2 dhcpd: [ID 702911 local7.info] DHCPACK on 172.28.41.179 to 00:11:43:42:b7:b2 (AMOOREXP) via 172.28.41.12
> >
> > Sep 18 12:46:48 hw1ns2 dhcpd: [ID 702911 local7.info] DHCPREQUEST for 172.28.41.179 (172.28.198.20) from 00:11:43:42:b7:b2 (AMOOREXP) via 172.28.41.11
> > Sep 18 12:46:48 hw1ns2 dhcpd: [ID 702911 local7.info] DHCPACK on 172.28.41.179 to 00:11:43:42:b7:b2 (AMOOREXP) via 172.28.41.11
> You have two relays (172.28.41.11 and 172.28.41.12).

> So there's nothing unusual about this.



We are receiving duplicate dhcp broadcasts because of a bug in the Cisco router code.

We run Cisco routers in HSRP, but due to a code bug, the inactive HSRP router is also sending the dhcp broadcast.  This is fixed in a later version, and we intend to upgrade.  BTW: this has caused (a very few) problems in the past where, because two broadcasts were sent, and maybe the dhcp servers (or network) were busy, the failover server got a reply back to the client first, and the client ended up on the wrong address.  We have a few very picky people who want the same IP every time.  According to Murphy's law, it is these picky people who will observe this anomaly - and they did.


> The client is probably wondering why it got two ack's, but this is
> pretty safe with most clients I've seen.

> > Sep 18 12:46:48 hw1ns2 dhcpd: [ID 702911 local7.info] DHCPDECLINE of 172.28.41.179 from 00:11:43:42:b7:b2 (AMOOREXP) via 172.28.41.12: not found

> There's no way for us to tell you why the client chose to do this.



I can not explain it either.  I don't see another machine on that IP.  If it doesn't happen again, I will not worry.


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