GigabitEthernet Trunk hangs when I add a subint to a bridge group

Discussion in 'Cisco' started by Rick Kunkel, Jan 25, 2007.

  1. Rick Kunkel

    Rick Kunkel Guest

    Hello all,

    I ran into something unsettling yesterday, and I'm hoping that someone
    can tell me why this happened, or if indeed it's even supposed to...

    We have a 7206 that has several ethernet customers attached to it, as
    well as having an ATM DS-3 module for DSL customers. We've got one
    ethernet customer that has been convincing people to order DSL through
    us, and he requests that they be bridged to his ethernet connection so
    that he can provide different kinds of services to them.

    Here's a show ver from my router:

    Cisco Internetwork Operating System Software
    IOS (tm) 7200 Software (C7200-IS-M), Version 12.2(4)BW1, EARLY
    DEPLOYMENT RELEASE SOFTWARE (fc1)

    The relevant lines (AFAIK) from the config are these (summarized for
    example's sake):

    !
    bridge irb
    !
    interface GigabitEthernet0/1
    description 802.1q Trunk to Network
    no ip address
    duplex full
    speed 1000
    media-type gbic
    negotiation auto
    !
    interface GigabitEthernet0/1.20
    description Ethernet Customer
    encapsulation dot1Q 20
    ip address X.X.X.X X.X.X.X
    !
    interface GigabitEthernet0/1.30
    description Bridge to DSL Customer on ATM2/0.123
    encapsulation dot1Q 30
    bridge-group 30
    !
    interface ATM2/0.123 point-to-point
    description DSL Customer Bridge to GigabitEthernet0/1.30
    class-int 3.0-768-atm
    pvc 1/123
    !
    bridge-group 30
    !
    bridge 30 protocol ieee
    !

    Brief description: The GigabitEthernet0/1 port goes into a 3550 via
    an 802.1q trunk, and the ethernet customer's stuff is hooked into one
    of the ports on that 3550. The port he's connected to is ALSO a trunk
    port, but I'm only allowing the VLANs associated with the bridges I'm
    creating. Gig0/1.20 is the ethernet customer's main subinterface,
    where he's got his equipment "connected". Gig0/1.30 is there to
    create another VLAN for the bridge 30 to the ATM2/0.123 interface. So
    essentially, the DSL customer is attached to ATM2/0.123, which is in a
    bridge group with Gig0/1.30, which passes over the trunks to his
    equipment.

    Here's the prob. While I'm creating Gig0/1.30, as SOON as I type
    bridge-group 30, BLAMMO, the Gig0/1 interface goes down. 30 seconds
    later, it's back and fine. It's like spanning tree is putting it into
    blocking mode or something. At least that's my best guess.

    Is my assessment correct? Other ideas? Is there a better way to do
    this?

    Thanks in advance!

    --Rick Kunkel
    Rick Kunkel, Jan 25, 2007
    #1
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  2. Rick Kunkel

    Marc Elsen Guest


    > ...
    > Here's the prob. While I'm creating Gig0/1.30, as SOON as I type
    > bridge-group 30, BLAMMO, the Gig0/1 interface goes down. 30 seconds
    > later, it's back and fine. It's like spanning tree is putting it into
    > blocking mode or something. At least that's my best guess.
    >
    > Is my assessment correct? Other ideas? Is there a better way to do
    > this?
    >


    - You can first of all enable logging on the interface,
    use this as extra statements in config for the interface params :

    logging event link-status
    logging event spanning-tree status
    logging event trunk-status


    Also in your global config , enable logging to an available
    syslog server as in :

    logging ip-of-syslog-server


    Then when the problem situation occurs , issue a :

    # show log

    on the switch, and check the syslog server's syslog file and lookup
    all entries from the switch.

    This may provide extra info.

    M.
    Marc Elsen, Jan 26, 2007
    #2
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