SV: DISCOVER bursts

[Glenn Satchell]

>
>There was a bug fix recently wrt to lease limit. When a lease is
>offered it has a 2 minute lease duration. If the client then comes back
>and requests it the lease offered has the normal lease duration
>(whatever you configured, or the client asked for). Until the lease is
>requested it's a sort-of temporary lease and not part of the lease
>limit yet.
>
>Does the dhcp client eventually accept one of the offers and send a
>request for it? If so, then the other temporary leases will expire in
>two minutes and go back to being available for other clients.
>
>Yes, it sounds like a client that's not well written, but the client
                                          
of course that should be the *server* should handle it!!

>should handle these cases and try to do something sensible.
>
>Not sure how many clients you have, but I suspect a Sun V210 could
>handle 10-50,000 clients easily depending on the lease time.
>
>regards,
>-glenn
>--
>Glenn Satchell     mailto:glenn.satchell at uniq.com.au | Some days we are
>Uniq Advances Pty Ltd         http://www.uniq.com.au | the flies;  some
>PO Box 70 Paddington NSW Australia 2021              | days we  are the
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>
>>From: "Lars Jacobsen" <lars-jacobsen at newmail.dk>
>>To: <dhcp-users at isc.org>
>>Subject: SV: DISCOVER bursts
>>Date: Sat, 6 Jan 2007 20:23:35 +0100
>>
>>Well I read the question as regardless of the CPE "misbehaver" (asking for
>>an IP address 4 times) the server should NEVER offer more than max two
>>addresses to a client in this particular config. But it does, why ?
>>
>>I expect Staffan has:
>>spawn with option agent.circuit-id;
>>lease limit 2;
>>somewhere in his config.
>>
>>Maybe as suggested an race/timing issue inside the server, keeping track on
>>offered not yet acknowledged leases, compared to some of the rules for this
>>specific client.
>>
>>
>>/Lars
>>
>>
>>
>>> -----Oprindelig meddelelse-----
>>> Fra: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] På vegne
>>> af Milton W. Schober, Jr.
>>> Sendt: 5. januar 2007 15:56
>>> Til: dhcp-users at isc.org
>>> Emne: Re: DISCOVER bursts
>>> 
>>> What is the CPE?  We have seen something similar with Thomson IPTV set top
>>> boxes, but the problem is in the STB, not the server.
>>> 
>>> Milton Schober
>>> ----- Original Message -----
>>> From: <Staffan.Ungsgard at teliasonera.com>
>>> To: <dhcp-users at isc.org>
>>> Sent: Friday, January 05, 2007 3:55 AM
>>> Subject: DISCOVER bursts
>>> 
>>> 
>>> > Hi
>>> > We have problem with a special customers CPE, where the CPE send four
>>> > rapid DHCPDISCOVERS with just 20 milliseconds apart.
>>> > When the DHCP server gets the DISCOVERS it issues different addresses on
>>> > each discover. I have snoop logs of the traffic, and the DISCOVERS are
>>> > indeed exactly the same in each DHCPDISCOVER. It seems that the when the
>>> > server handles the second DISCOVER, it doesn't "remeber" that is has
>>> > already offered a fresh ip address from an identical DHCPDISCOVER 20 ms
>>> > earlier.
>>> > To furthermore illustrate this, we have a lease limit of two, so
>>> > technically it shouldn't offer more than two addresses to the same line
>>> > identifier even if the "Client Identifier" differed, but it isses three
>>> > different addresses and only barfs at the fourth DHCPDISCOVER saying "no
>>> > billing".
>>> >
>>> > Is there a race problem in the dhcp server ?
>>> >
>>> > The hardware is a Sun V210 running Solaris 8. No supermachine, but
>>> they're
>>> > still selling them.
>>> >
>>> > Best Regards
>>> >
>>> > -- Staffan Ungsgard
>