My customer has a number of Cat5509s with RSMs. They are using secondary addresses on the RSM VLAN interfaces and have configured DHCP static mappings. With this configuration, they are able to serve DHCP addresses to hosts on both the primary and secondary subnets. The RSM config is straightforward (ip address, secondary ip address and helper address). I am surprised that this works at all; my understanding was that the DHCP relay always uses the primary subnet. Anyway, the same customer has now installed a number of Cat4006 switches with WS-X4232-L3 routing modules and they are unable to serve DHCP addresses to hosts on the secondary subnets, even when they are statically mapped. I have reproduced this in the lab. I have used the latest version of WS-X4232-L3 IOS and have not been able to make this work. Does anyone know why this should work with a Cat5509 and not a Cat4006? Any ideas on a workaround or when this will be supported with the Cat4006? Many thanks!
