Abandoned messages.

Keith kwoody at citytel.net
Tue Jan 8 20:07:36 UTC 2008

On Tue, 8 Jan 2008, Niall O'Reilly wrote:

|->On 8 Jan 2008, at 19:17, Keith wrote:
|->> Why would a client go through the whole discover/offer/request/ack
|->> then
|->> the server at the end of it say declined, when the client ACK'd the
|->> request?
|->	I think you mean, "when the client REQUESTed the lease",
|->	as the ACK is from the server.
|->	I'm seeing this on some of our networks too.  So far, it seems
|->	not to be hurting, so we've not begun to treat it as "urgent".
|->	It is on my list for attention quite soon.
|->	I have no hard information yet, but I suspect rogue clients with
|->	manually configured addresses interfering with the well-behaved.
|->	In more detail, but without having thought too much about it,
|->	I guess what's happening is the following.
|->		client DISCOVER
|->		server OFFER
|->		client REQUEST
|->		[ server can't see address in use,
|->		  as we block ICMP to a (too) large extent ]
|->		server ACK
|->		client checks for address in use
|->		client DECLINE

I think thats somewhat along the lines of whats happening here and I did
typo the ACK..I meant the server. As Ive been looking at this further
I am inclined to believe it is from pool exhaustion at this point.

When I was on vacation last year my boss added an extra piece of gear to
this subnet when he wasnt supposed to, and its coming back to bite me now.

Ive been comparing MAC addresses that are trying for 2 different declined
IP's and in both cases there are 5 clients trying for the same 2 IP's and
4 of them are the same in both cases.


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