[c-nsp] Cisco 1841 simple bridging

[Doug McIntyre]

On Sat, Jun 07, 2008 at 10:40:03AM -0500, Pablo Almido wrote:
> Hi folks, I am trying configure simple bridging in a router 1841, because I
> need that it works in mode bridge, I will put I firewall beetween this
> router and ISP router, and I want to use QoS features of cisco router 1841,
> it is possible configure in router cisco1841, how I can reach it?
> 
> Router ISP ---------      Router 1841  (bridge) ------------  Firewall
> 
> I have execute the following commands, but I get a error.
> 
> router(config)#bridge 1 protocol ieee
> router(config)#bridge irb
> router(config)#int fa0/0/0
> router(config-if)#bridge-group 1
> FastEthernet0/0/0 does not support bridging
> router(config-if)#exit


Fa0/0/0 implies that you have a Ether HWIC Switch in the box. You
can't directly bridge switch ports.

You can only bridge routed ports (ie. Fa0/0) two zeros, not three.

If you really want to use the Ether Switch HWIC, you probably want to
setup a SVI VLAN device, put your switch ports into that VLAN, and
bridge that SVI to the the other bridge-group 1 interface (which I'm
assuming is a router port). If the other port is not a router port
either, then its even easier, you put your two switch ports into a
private VLAN, and forget about it.

If you wanted to use tradition IRB only without SVIs and switch ports,
you probably should have got a different router.. :( As you can't get
more router ports than the two it comes with into this chassis.