[c-nsp] Catalyst 6500 series switches and Cisco 7600 series routers do not support Integrated routing and bridging (IRB)

[Brett Frankenberger]

On Mon, May 16, 2005 at 05:28:15PM +0200, Manu Chao wrote:
> Hi there,
> 
> I need to use IRB with bridge protocol IEEE on a 6500 running IOS
> Version 12.2(18)SXD2 but this feature doesn't exist anymore. I
> understand why but I need it ;-)
> 
> I need to bridge n L2 VLANs ending on the 6500 to one L3 VLAN local to
> this same 6500.
> 
> ---- vlan 201---->
> 
> ---- vlan 202---->
> 
>                               I R B  ----> vlan 200 (IP 10.0.0.1/24)
> 
> ---- vlan 203---->        
> 
> ---- vlan 204---->        
> 
> "Catalyst 6500 series switches and Cisco 7600 series routers do not
> support Integrated routing and bridging (IRB)"
> 
> Can someone find a solution (other than downgrading to release 11) or
> a workaround?

If you're willing to eat ports and accept some additional points of
failure:
   int gi3/1           <--- Obviosuly, my port names are hypothetical
     switchport mode access
     switchport access vlan 201
   int gi3/2
     switchport mode access
     switchport access vlan 202
   int gi3/3
     switchport mode access
     switchport access vlan 200
   int gi3/4 
     switchport mode access
     switchport access vlan 200
Then connect 3/1 and 3/3 with a crossover cable, and connect 3/2 and 3/4
with a crossover cable.  (I only showed vlan 201 and 202 above ... you
can extend the example to vlan 203 and 204.)

Alternatively, you can probably bridge Vlan 201/202/203/204 togethor
internally (if CRB works on 6500s -- I haven't tried), then you only
need to use the "Crossover cable hack" to connect one of those vlans to
vlan 200.

Note that bridging (with or without IRB) isn't implemented in hardware,
so performance will be lower.

     -- Brett