Clients keep sending DHCPDECLINE
moffe at zz9.dk
moffe at zz9.dk
Sun Aug 22 19:33:30 UTC 2010
Hi Marc
Thank you for the suggestion. I am currently dumping arp traffic (of
course, now the problem does not show up!)
I am unable to dump as:
1) It seems random which clients are affected,
2) I currently have no equipment at hand to dump
It is a residential network, so people set up a multitude of equipment,
brands, models, configurations etc. so the problem might come from
almost anywhere. I am not aware that any proxy-arp equipment is
installed, but of course someone might have installed just about
anything. Rogue DHCP-servers happens often, but I am mostly on top of
these (one sending NAKs but not OFFERs would be unusual).
I will try to get my hands on a two-NIC computer able to run tcpdump to
place between an affected computer and the network.
If anyone else should have other suggestions in the meantime, I would be
very happy.
Best regards and thank you
/Rasmus
Den 20-08-2010 15:57, Marc Perea skrev:
> Hi Rasmus,
> this problem can have a few different causes, but I remember having a
> similar issue when we had Vista attached to a Cisco relay agent on a
> router. After specific positioning of a packet capture to identify the
> behavior, Vista sends a gratuitous arp after the ACK as one final
> check to see if anyone else on the network has that IP before binding
> it to its interface for use. Unfortunately for us, our Cisco router
> was answering that arp with its own MAC, presumably identifying that
> the Cisco could get to that IP so it responded to the arp by proxy. We
> did a no ip proxy-arp on that interface and our router stopped
> responding to the g-arps, and things were quiet (and working).
> Not sure if this is the case for you or not, but I'd at least get a
> sniff going just north of the client to see what situation is
> occurring that causes the client to DECLINE - delayed NAK perhaps from
> another piece of gear?
> HTH -- Marc
>
> >Over the last months I have suddenly seen a behaviour, that is new to
> >me:
> >
> >1) Client DHCPDISCOVERs
> >2) Server DHCPOFFERs
> >3) Client DHCPREQUESTs
> >4) Server DHCPACKs
> >5) Client DHCPDECLINEs
> >6) Server abandons IP
> >7) Goto 1, with new IP
>
>
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--
Rasmus Bøg Hansen || http://www.zz9.dk/
moffe at zz9.dk ||
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