I've configured an 876 (IOS: advipserv 12.4(6T)) as dhcp relay.
The 876 is connected to a backbone MPLS via ADSL and ISDN (backup to POP).
When the router works on ADSL...seems that the dhcp requests are not forwarded towards the DHCP server...On the contrary, on isdn line all works fine.
With a debug ip packet detail I can see the dhcp packet originated by the 'relay': (10.232.130.1 is the dhcp server; 10.196.127.253 is the ip lan of my router; Bvi1 is the wan interface bridged on Atm interface
Sep 17 16:40:54.046: IP: tableid=0, s=10.196.127.253 (local), d=10.232.130.1 (BVI1), routed via FIB
Sep 17 16:40:54.046: IP: s=10.196.127.253 (local), d=10.232.130.1 (BVI1), len 604, sending
Sep 17 16:40:54.046: UDP src=67, dst=67
but on the central site I can't see these packets.
My SP told me that any drop is done by the network.
If i try doing icmp request towards the dhcp server (10.232.130.1) with source the IP Lan, all works fine..
Many thanks in advance