I am working on a project for a customer that has a 1841 ISR with a HWIC-AP-AG-B wireless card installed. They also have an autonomous AIR-CAP3502I-A-K9 that will need to attach to one of the Ethernet ports on the router. Ideally both APs would use the same SSIDs (2) to enable roaming when the wireless client is out of range of one of the APs, read same SSID = same VLAN in 1841.
The issue is in the router how the dot11 interfaces bind within the router. The 3502is connected to fa0/1; the 3502 is configured for two SSIDs like the router. Therefore fa0/1 is configured as a trunk with sub-interfaces that correspond to the two SSID VLANs and a native VLAN. With the IP addresses (gateway addresses) assigned to the fa0/1 sub-interfaces the SSIDs function as expected, however the SSIDs on the HWIC-AP-AG-B will not function in this configuration. In order to get the SSIDs in the HWIC-AP-AG-B functioning I have to create a BVI interface for each VLAN with the dot11 and bvi interfaces in the bridge group. Of course the BVI has to have an IP address assigned to it as an endpoint for the wireless clients, since it is a router these have to be unique subnets. This creates a situation where fa0/1 is divided into fa0/1.1, fa0/1.500 and fa0/1.550 with two BVI interfaces BVI50 and BVI55. This creates an environment where the SSIDs on the AP are assigned to one IP subnet and the SSIDs on the HWIC-AP-AG-B are assigned to another IP subnet.
The question is how can I bind the HWIC-AP-AG-B dot11 interfaces to the corresponding Ethernet sub-interfaces so that both wireless devices are within the same IP subnet. These AP HWICs function much differently than an AP, with an AP you have one BVI (native VLAN) interface that trunks all of the VLANs on the AP to a switch or router. The HWIC doesn't work this way. I have attached the config of the 1841, I also have a HWIC-4ESW available however this further complicates the matter since the built in interfaces cannot be assigned to VLANs on the HWIC-4ESW.
Cheers,
Sam
