While preparing a Cisco Router 851w for a SOHO implementation I run into couple of issues. I tried to configure the router from the http interface but soon I figured out this is not the right way. I configured many switches, routers and access points but never a integrated one like the 851W. While working from the default configuration VLAN1 was assigned a static IP address in the 10.x.x.x range; I changed the IP address and start working to configure the wireless LAN before moving the NAT and VPN configuration. For two hours working on this device and trying different ways to configure the router I finally go the configuration working.

bridge irb

!interface Dot11Radio0
 no ip address
 !
 encryption vlan 1 mode ciphers tkip
 !
 broadcast-key vlan 1 change 30
 !
 ssid networknet
 !
 speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 12.0 18.0 24.0 36.0 48.0 54.0
 station-role root
!
interface Dot11Radio0.1
 encapsulation dot1Q 1 native
 no cdp enable
 bridge-group 1
 bridge-group 1 subscriber-loop-control
 bridge-group 1 spanning-disabled
 bridge-group 1 block-unknown-source
!
interface Vlan1
 no ip address
 bridge-group 1
 bridge-group 1 spanning-disabled
!
interface BVI1
 ip address 192.168.142.1 255.255.255.0
 ip nat inside
 ip virtual-reassembly
!

I tried to assign static IP address to BVI1 and VLAN1 interface which are than overlapping. At some point I decided to remove the IP address from VLAN1 and than only configure BVI1 interface with the IP address I had assigned to VLAN1. This action helped me finally to get the wireless LAN working with WPA key and DHCP enabled. The last thing which I could not figure out is when plugging a network cable to port Fa0 – Fa3 no IP address was given from the DHCP pool. I finally found a post talking about bride-group and assigning that to VLAN1. This worked and I am almost finished with configuring this device.

Click here to view Cisco Router 851W example configuration I used to configure my router.

Related links:

• Cisco Router 851 – 871 Interfaces and Basic Configuration
• Wireless Authentication Types on a Fixed ISR Configuration Example
• Cisco: Broadcasting Multiple SSIDs