Catalyst 3750 cross-stack ether channel

Discussion in 'Cisco' started by Will, Jan 29, 2004.

  1. Will

    Will Guest

    I have two stacks of Catalyst 3750 switches, each stack has 2 members.
    I want to connect the two stacks together using four 1000BASE-SX
    connections, in a fully meshed configuration.

    1-----3
    \ /
    \ /
    / \
    / \
    2-----4

    (Where 1 and 2 form a stack, and 3 and 4 form a stack)

    I want to aggregate the 4 links into one etherchannel. As far as I
    know the 3750 supports cross-stack etherchannel. However when I try
    this configuration, it only lasts 30 seconds before the console gives
    a "misconfiguration error". Has anyone else tried this configuration?
    My guess is that the switches can only support cross-stack
    etherchannel when one of the ends of the etherchannel has all wires
    terminating on the same switch. I've sucessfully got it working in
    that configuration using only two links, but as soon as I try fully
    meshed with 4 it breaks again. Any help would be much appreciated!!

    Will
     
    Will, Jan 29, 2004
    #1
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  2. Will

    AnyBody43 Guest

    (Will) wrote in message news:<>...
    > I have two stacks of Catalyst 3750 switches, each stack has 2 members.
    > I want to connect the two stacks together using four 1000BASE-SX
    > connections, in a fully meshed configuration.
    >
    > 1-----3
    > \ /
    > \ /
    > / \
    > / \
    > 2-----4
    >
    > (Where 1 and 2 form a stack, and 3 and 4 form a stack)
    >
    > I want to aggregate the 4 links into one etherchannel. As far as I
    > know the 3750 supports cross-stack etherchannel. However when I try
    > this configuration, it only lasts 30 seconds before the console gives
    > a "misconfiguration error". Has anyone else tried this configuration?
    > My guess is that the switches can only support cross-stack
    > etherchannel when one of the ends of the etherchannel has all wires
    > terminating on the same switch. I've sucessfully got it working in
    > that configuration using only two links, but as soon as I try fully
    > meshed with 4 it breaks again. Any help would be much appreciated!!
    >
    > Will



    Hi,

    The documentation certainly says that it works.

    Etherchannel is not for the fainthearted, read all of the guidelines
    and requirements and if it doesn't go get professional help.

    I suggest:
    Use channel mode desirable.
    Hard configure trunking
    I seem to recall that all ports in a channel have to be
    identical with respect to VLANS configured.
    Enable udld.
    Enable STP (in case the channel goes down).
    Enable STP protections. Those XXX-Guard things.

    For troubleshooting look at logs, raise/lower? logging level
    to get more info.

    Good luck.
     
    AnyBody43, Jan 30, 2004
    #2
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  3. Will

    shope Guest

    "AnyBody43" <> wrote in message
    news:...
    > (Will) wrote in message

    news:<>...
    > > I have two stacks of Catalyst 3750 switches, each stack has 2 members.
    > > I want to connect the two stacks together using four 1000BASE-SX
    > > connections, in a fully meshed configuration.
    > >
    > > 1-----3
    > > \ /
    > > \ /
    > > / \
    > > / \
    > > 2-----4
    > >
    > > (Where 1 and 2 form a stack, and 3 and 4 form a stack)
    > >
    > > I want to aggregate the 4 links into one etherchannel. As far as I
    > > know the 3750 supports cross-stack etherchannel. However when I try
    > > this configuration, it only lasts 30 seconds before the console gives
    > > a "misconfiguration error". Has anyone else tried this configuration?
    > > My guess is that the switches can only support cross-stack
    > > etherchannel when one of the ends of the etherchannel has all wires
    > > terminating on the same switch. I've sucessfully got it working in
    > > that configuration using only two links, but as soon as I try fully
    > > meshed with 4 it breaks again. Any help would be much appreciated!!
    > >
    > > Will

    >
    >
    > Hi,
    >
    > The documentation certainly says that it works.
    >
    > Etherchannel is not for the fainthearted, read all of the guidelines
    > and requirements and if it doesn't go get professional help.
    >
    > I suggest:
    > Use channel mode desirable.
    > Hard configure trunking
    > I seem to recall that all ports in a channel have to be
    > identical with respect to VLANS configured.
    > Enable udld.
    > Enable STP (in case the channel goes down).
    > Enable STP protections. Those XXX-Guard things.


    try the latest code - or at least read the release notes for later
    versions - this is still newish kit, so there may be some bugs involved.

    some etherchannels seem to work better when the sequence of ports on the 2
    devices are consistant - ie 1/1 to 1/1, 1/3 to 2/1. 2/1 to 2/2 and so on.
    >
    > For troubleshooting look at logs, raise/lower? logging level
    > to get more info.
    >
    > Good luck.

    --
    Regards

    Stephen Hope - remove xx from email to reply
     
    shope, Jan 30, 2004
    #3
  4. Will

    Knowledge

    Joined:
    Oct 31, 2009
    Messages:
    2
    Will,

    Cross-Stack EtherChannel cannot be used with PAgP. You will have to set up your EtherChannel as either "ON" or use LACP. I just did it successfully with two 3750s. For example

    ===Stack 1===
    switch(config)#interface range 1/0/1 - 4
    switch(config-if)#channel-group 1 mode on
    switch(config-if)#exit
    switch(config)#interface range 2/0/1 - 4
    switch(config-if)#channel-group 1 mode on
    switch(config-if)#exit

    Make sure when specifing the ports that you indiate 1 or 2 for the switch in the stack.

    Hope this helps
     
    Last edited: Nov 9, 2009
    Knowledge, Nov 9, 2009
    #4
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