Cisco WLAN controller 4400 and dhcp relay

[karczewski cyrill]

Hi!!!
You are a master DAVID!!

Where could i find this version?

Thank you very much.

Cyrill KARCZEWSKI
Service Informatique
Hôpital Saint-Louis
1 Avenue Claude Vellefaux
75010 PARIS
0142499208

----- Message d'origine -----
De: wlanmac <wlan at mac.com>
Date: Mardi, Juillet 7, 2009 9:22 pm
Objet: Re: Cisco WLAN controller 4400 and dhcp relay
À: chilli at coova.org


> I updated the Subversion with the latest changes.. I checked the ARP
> replies... looks like I already fixed it. 
> 
> The new chilli does some things a bit differently. You'll find a new
> utility, called chilli_opt, which is the only binary that is linked with
> the configuration parsing (code generated by gengetopt). chilli server
> will launch this to parse out and build up a binary configuration file.
> chilli server will then re-read this configuration file, loading in the
> new configuration without any delays (no more stalling for DNS
> lookups). 
> 
> Enjoy,
> David
> 
> 
> On Mon, 2009-07-06 at 11:38 +0200, Thomas Liske wrote:
> > Hi,
> > 
> > karczewski cyrill wrote:
> > > Hello everyone!! I hope you are fine!!
> > > 
> > > I have a problem with coova-chilli 1.0.13 and i will be so 
> gratefull for anyone find a solution.
> > > 
> > > I use a cisco WLAN controller 4400 with vlans configured. in order 
> to transmit dhcp requests in that vlan, cisco has a dhcp relay.
> > > 
> > > the problem is that before transmit dhcp requests to chilli, the 
> cisco controller does an ARP request to chilli.
> > > 
> > > Chilli reply, but the cisco controller doesn't like this answer.
> > > 
> > > In fact, when chilli reply, in the ARP target address field, 
> chilli put 0.0.0.0 instead of the cisco controller ip address. It send 
> the ARP reply in broadcast mode.
> > > 
> > > So, the cisco controller send an ARP request again and again...
> > > 
> > > here is the cisco request:
> > > 
> > > http://picasaweb.google.com/cyrill51/Chillispot#5355257375354395602
> > > 
> > > here is the reply
> > > 
> > > http://picasaweb.google.com/cyrill51/Chillispot#5355257377945980914
> > > 
> > > Anyone has an idea to correct this in chilli or in the cisco controller.
> > > 
> > 
> > it seems to be an issue on the WLC implementation. According to 
> RFC826 
> > the WLC should accept the arp reply with an zero target address:
> > 
> > 
> > ==============================[RFC826]==============================
> > ?Do I have the hardware type in ar$hrd?
> > Yes: (almost definitely)
> >    [optionally check the hardware length ar$hln]
> >    ?Do I speak the protocol in ar$pro?
> >    Yes:
> >      [optionally check the protocol length ar$pln]
> >      Merge_flag := false
> >      If the pair <protocol type, sender protocol address> is
> >          already in my translation table, update the sender
> > 	hardware address field of the entry with the new
> > 	information in the packet and set Merge_flag to true.
> >      ?Am I the target protocol address?
> >      Yes:
> >        If Merge_flag is false, add the triplet <protocol type,
> >            sender protocol address, sender hardware address> to
> >           the translation table.
> >        ?Is the opcode ares_op$REQUEST?  (NOW look at the opcode!!)
> >        Yes:
> > 	Swap hardware and protocol fields, putting the local
> >             hardware and protocol addresses in the sender fields.
> > 	Set the ar$op field to ares_op$REPLY
> > 	Send the packet to the (new) target hardware address on
> >             the same hardware on which the request was received.
> > ==============================[RFC826]==============================
> > 
> > There are no checks on the target address for ARP replies. The arp 
> reply 
> > is btw not send as a broadcast, there is the WLC's ARP address 
> specified 
> > as the destination address in the ethernet header.
> > 
> > I'd just checked Linux's implementation on sending ARP replies, it 
> sets 
> > the target IP address to the original request source address. Maybe 
> it 
> > should be fixed in cc to perform as other common ARP implementations 
> 
> > perform.
> > 
> > 
> > Regards,
> > Thomas
> > 
> 
> 
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