Option82 class matching problem

[Glenn Satchell]

>Date: Tue, 30 Dec 2008 17:27:33 +0200
>From: Oleg Gawriloff <barzog at telecom.by>
>To: dhcp-users at lists.isc.org
>Subject: Option82 class matching problem
>
> I'll have very simple setup:
> L2 switch with Option82 activated
> Cisco Router working as DHCP server (client interfacase on which relay 
> is configures is 10.254.254.1/32, interface to dhcp server is 
> 172.16.2.21/24)
> ISC DHCP server with 172.16.2.242/24 address. Address 10.254.254.1 is 
> accessible from dhcp server.
> 
> ISC setup is:
> use-host-decl-names on;
> ddns-update-style none;
> class "p2626-sha19/9"
> {
>     match if binary-to-ascii (10, 8, ".", option agent.circuit-id)="0.9";
>     log(debug,"Class p2626-sha19/9 matched");
> }
> subnet 172.16.2.0 netmask 255.255.255.0
> { }
> subnet 10.254.254.0 netmask 255.255.255.0
> {
>     authoritative;
>     option routers 10.254.254.1;
>     pool { range 10.254.254.128 10.254.254.192; allow members of 
> "p2626-sha19/9"; }
> }
> 
> With empty dhcpd.leases file in log I see following:
> [root at albatros2 /usr/local/src/dhcp-4.0.0]# dhcpd -cf 
> /usr/local/etc/dhcpd.conf -lf /var/db/dhcpd/dhcpd.leases -d vlan0
> Internet Systems Consortium DHCP Server V3.0.7
> Copyright 2004-2008 Internet Systems Consortium.
> All rights reserved.
> For info, please visit http://www.isc.org/sw/dhcp/
> Wrote 0 leases to leases file.
> Listening on BPF/vlan0/00:1e:0b:5a:d4:17/172.16.2/24
> Sending on   BPF/vlan0/00:1e:0b:5a:d4:17/172.16.2/24
> Sending on   Socket/fallback/fallback-net
> DHCPDISCOVER from 00:17:08:47:54:34 via 10.254.254.1: network 
> 10.254.254/24: no free leases
>  Lease for 10.254.254.192 Switch CID: 0.9 Switch RID: 192.168.0.150
> Class p2626-sha19/9 matched
> DHCPDISCOVER from 00:17:08:47:54:34 via 10.254.254.1
> DHCPOFFER on 10.254.254.192 to 00:17:08:47:54:34 (by171tobookhp) via 
> 10.254.254.1
> DHCPREQUEST for 10.254.254.192 (172.16.2.242) from 00:17:08:47:54:34 via 
> 10.254.254.1: lease 10.254.254.192 unavailable.
> DHCPNAK on 10.254.254.192 to 00:17:08:47:54:34 via 10.254.254.1
>  Lease for 10.254.254.192 Switch CID: 0.9 Switch RID: 192.168.0.150
> Class p2626-sha19/9 matched
> DHCPREQUEST for 10.254.254.192 (172.16.2.242) from 00:17:08:47:54:34 
> (by171tobookhp) via 10.254.254.1
> DHCPACK on 10.254.254.192 to 00:17:08:47:54:34 (by171tobookhp) via 
> 10.254.254.1
> 
> I've really don't understand why its two DHCPDISCOVER (first one with 
> 'no free leases'), and why after successfull class matching there is 
> 'lease unavailable' error and DHCPNAK?
> Last two entries at dhcpd.leases:
> lease 10.254.254.128 {
>   starts 2 2008/12/30 14:14:02;
>   ends 2 2008/12/30 14:14:09;
>   tstp 2 2008/12/30 14:14:09;
>   cltt 2 2008/12/30 14:14:02;
>   binding state free;
>   hardware ethernet 00:17:08:47:54:34;
>   uid "\001\000\027\010GT4";
> }
> lease 10.254.254.128 {
>   starts 2 2008/12/30 14:14:18;
>   ends 3 2008/12/31 02:14:18;
>   cltt 2 2008/12/30 14:14:18;
>   binding state active;
>   next binding state free;
>   hardware ethernet 00:17:08:47:54:34;
>   uid "\001\000\027\010GT4";
>   option agent.circuit-id 0:9;
>   option agent.remote-id c0:a8:0:96;
>   client-hostname "by171tobookhp";
> }
> Is someone can shed some light on this issue and point me to the right 
> direction?

Hi Oleg

This might be related to the recent posting regarding Linux and vlans
(I see you are using vlan0 as the network device). It was something
along the lines of a recent Linux kernel update now presents the raw
packet with the vlan tag and also presents it to the ethernet without
the vlan tag for some reason.  Searching the archives within the last
month or so should find the original posts with more details.

Perhaps using tcpdump might show what's going on?

regards,
-glenn