Cisco 2811 with HWIC-4ESW

Discussion in 'Cisco' started by Houston SBC, Oct 2, 2007.

  1. Houston SBC

    Houston SBC Guest

    I have a Cisco 2811 running IOS adventerprisek9-mz.12.4-15.T and a HWIC-4ESW

    Does anyone have the foggiest idea of how to get fa0/0 to share a vlan with
    fa0/0/0-3 (the ports on the HWIC-4ESW).

    Any config files, urls, etc would be greatly appreciated.

    Appendix D of the Cisco Field Manual: Catalyst Sw. Config covers "Extending
    VLANs within Layer 3 switches" and seems to be close but it shows a 802.1Q
    trunk line from the layer3 device to the layer 2 device--How's it handled
    when it is in the same box?


    [email protected](8888nospam!!!!)
    Houston SBC, Oct 2, 2007
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  2. Houston SBC

    response3 Guest

    Can't do it, since the built-in port is layer 3 only, and is not
    capable of running in layer 2 mode. It can only route traffic for
    vlan's but not act as an access port to a vlan.
    response3, Oct 4, 2007
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  3. Houston SBC

    Mike Dorn Guest

    Actually, I did this just yesterday with a 2811 and the 9-port switch module. I
    eventually tore it back down again because it ate up cpu and it wasn't all that
    essential for me to have the other interface.

    What you have to do is turn on bridging. Then you create a bridge virtual
    interface for the router to use instead of the vlan interface that connects to
    the switch module. Join both the vlan interface from the switch and the
    physical interface from the ouside of the router into the bridge group, and
    they're together.

    bridge irb
    int fa0/0
    no ip address
    bridge-group 1
    int bvi 1
    ip address x.x.x.x y.y.y.y
    int vlan 3
    bridge-group 1
    int fa0/0/2
    switchport access vlan 3
    bridge 1 protocol ieee
    bridge 1 route ip

    What I did was similar, except that I was making my fa0/0 into a trunk to reach
    external switches, so each dot1q subinterface under it was linked to a separate
    bridge group. The 9-port module was then configured with one vlan for data and
    the other for voice to support ip phones. When I had it working, however, it
    chewed up 10-30% cpu with almost no traffic load. Shut down fa0/0, got rid of
    the bvi's and made the 9th port on the module into a trunk instead, and cpu ran
    about 1-2%, so that's where I'm leaving it. My guess would be that the bvi's
    are implemented in software, so don't optimize as well. Of course, your
    situation may require you to use the other ports, so go ahead & try it.

    I haven't messed with bridging on routers all that much, so it's also possible
    that I missed something--the cpu hit may be avoided by application of slightly
    cleverer code...
    Mike Dorn, Oct 4, 2007
  4. Houston SBC

    Houston SBC Guest

    First, thanks for the info. Cisco docs are somewhat lacking in certain
    It is always nice to see someone else going where no one else has gone

    Houston SBC, Oct 4, 2007
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