BPDU problem

Discussion in 'Cisco' started by Rob, Jul 8, 2009.

  1. Rob

    Rob Guest

    see the folloing logs:

    001918: .Jul 2 00:44:28.825 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    Interface FastEthernet0/48, changed state to down

    001919: .Jul 2 00:44:33.540 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    Interface FastEthernet0/48, changed state to up



    001934: .Jul 5 06:38:17.506 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    Interface FastEthernet0/48, changed state to down

    001935: .Jul 5 06:38:22.321 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    Interface FastEthernet0/48, changed state to up



    001936: .Jul 8 06:03:01.727 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    Interface FastEthernet0/48, changed state to down

    001937: .Jul 8 06:03:06.333 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    Interface FastEthernet0/48, changed state to up



    This fastethernet 0/48 is connecting to another switch called 3750-IT
    (10.10.7.254). Show log on this switch gives you:



    Ethernet2/0/19 with BPDU Guard enabled. Disabling port. (3750-IT-2)Jul 8
    14:50:38.487 EDT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Fast

    Ethernet2/0/19 with BPDU Guard enabled. Disabling port. (3750-IT-2)030459:
    Jul 8 14:50:40.475 EDT: %LINK-3-UPDOWN: Interface FastEthernet2/0/19,
    changed state to down

    Jul 8 14:55:36.073 EDT: %PM-4-ERR_RECOVER: Attempting to recover from
    bpduguard err-disable state on Fa2/0/19 (3750-IT-2)

    030460: Jul 8 14:55:39.722 EDT: %LINK-3-UPDOWN: Interface
    FastEthernet2/0/19, changed state to up

    Jul 8 14:55:40.460 EDT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port
    FastEthernet2/0/19 with BPDU Guard enabled. Disabling port. (3750-IT-2)

    Jul 8 14:55:40.460 EDT: %PM-4-ERR_DISABLE: bpduguard error detected on
    Fa2/0/19, putting Fa2/0/19 in err-disable state (3750-IT-2)

    Jul 8 14:55:40.502 EDT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port
    FastEthernet2/0/19 with BPDU Guard enabled. Disabling port. (3750-IT-2)



    Any idea how to fix this issue?

    Thanks in advance.

    Rob
    Rob, Jul 8, 2009
    #1
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  2. Rob

    Thrill5 Guest

    On the 3750, turn off portfast on interface that connects to other switch.
    "no spanning-tree portfast".

    BPDU guard works in conjuction with portfast. Portfast is used on
    interfaces that are not connecting to other L2 devices (switches), so that
    the interface will come up right away instead of waiting for spanning-tree
    to determine if another switch is connected to it. When spanning-tree is
    enabled, when a port comes up, the port is put into "listening" mode for 30
    seconds. During this time, the switch can receive packets, but no packets
    are sent, other than spanning-tree BPDU's. Even though the port is "up" no
    traffic can be passed. After 30 seconds, the port is moved to the
    "forwarding" state and traffic is then able to be sent and received. When
    portfast is enabled, the port comes up right away both sending and receiving
    traffic. When you are enabling portfast, you are saying that "no layer 2
    device should be connected to this port so enable it right away". If a BPDU
    (spanning-tree packet) is received on a port with portfast enabled, normal
    spanning tree methods are invoked immediately. The port goes into "listen"
    mode for 30 seconds. When BPDU guard is enabled, instead of starting the
    normal spanning-tree protocol initialization, the port is instead disabled.

    "Rob" <> wrote in message news:4a54f9d8$...
    >
    >
    > see the folloing logs:
    >
    > 001918: .Jul 2 00:44:28.825 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    > Interface FastEthernet0/48, changed state to down
    >
    > 001919: .Jul 2 00:44:33.540 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    > Interface FastEthernet0/48, changed state to up
    >
    >
    >
    > 001934: .Jul 5 06:38:17.506 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    > Interface FastEthernet0/48, changed state to down
    >
    > 001935: .Jul 5 06:38:22.321 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    > Interface FastEthernet0/48, changed state to up
    >
    >
    >
    > 001936: .Jul 8 06:03:01.727 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    > Interface FastEthernet0/48, changed state to down
    >
    > 001937: .Jul 8 06:03:06.333 EDT: %LINEPROTO-5-UPDOWN: Line protocol on
    > Interface FastEthernet0/48, changed state to up
    >
    >
    >
    > This fastethernet 0/48 is connecting to another switch called 3750-IT
    > (10.10.7.254). Show log on this switch gives you:
    >
    >
    >
    > Ethernet2/0/19 with BPDU Guard enabled. Disabling port. (3750-IT-2)Jul 8
    > 14:50:38.487 EDT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Fast
    >
    > Ethernet2/0/19 with BPDU Guard enabled. Disabling port. (3750-IT-2)030459:
    > Jul 8 14:50:40.475 EDT: %LINK-3-UPDOWN: Interface FastEthernet2/0/19,
    > changed state to down
    >
    > Jul 8 14:55:36.073 EDT: %PM-4-ERR_RECOVER: Attempting to recover from
    > bpduguard err-disable state on Fa2/0/19 (3750-IT-2)
    >
    > 030460: Jul 8 14:55:39.722 EDT: %LINK-3-UPDOWN: Interface
    > FastEthernet2/0/19, changed state to up
    >
    > Jul 8 14:55:40.460 EDT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on
    > port FastEthernet2/0/19 with BPDU Guard enabled. Disabling port.
    > (3750-IT-2)
    >
    > Jul 8 14:55:40.460 EDT: %PM-4-ERR_DISABLE: bpduguard error detected on
    > Fa2/0/19, putting Fa2/0/19 in err-disable state (3750-IT-2)
    >
    > Jul 8 14:55:40.502 EDT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on
    > port FastEthernet2/0/19 with BPDU Guard enabled. Disabling port.
    > (3750-IT-2)
    >
    >
    >
    > Any idea how to fix this issue?
    >
    > Thanks in advance.
    >
    > Rob
    >
    >
    >
    >
    >
    >
    >
    >
    >
    >
    Thrill5, Jul 8, 2009
    #2
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  3. Rob wrote:

    >Any idea how to fix this issue?


    Two options.

    1. Turn BPDU-Guard off
    2. Disconnect the switch/bridge attached to the port.
    --
    Paul Matthews CCIE #4063
    Please post questions to the NG, NOT by e-mail.
    Paul Matthews, Jul 21, 2009
    #3
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