etherchannel/lacp question

Discussion in 'Cisco' started by cconnell_1, Apr 17, 2008.

  1. cconnell_1

    cconnell_1 Guest

    I configured lacp between a cisco switch and a nortel load balancer.

    Could someone tell me what "default" port means in the cisco output
    below, and what the effect of this is, i read somewhere its the port
    where multicast traffic is sent on, i cant find it in any books. I
    noticed if i change "system priority higer on my switch than the
    nortel the default port changes to 4, i cant work out why.

    Thanks for any help

    Switch#sh etherchannel summary
    Flags: D - down P - in port-channel
    I - stand-alone s - suspended
    H - Hot-standby (LACP only)
    R - Layer3 S - Layer2
    u - unsuitable for bundling
    U - in use f - failed to allocate aggregator
    d - default port

    Number of channel-groups in use: 1
    Number of aggregators: 1

    Group Port-channel Protocol Ports
    3 Po3(SU) LACP Fa0/3(Pd) Fa0/4(P)
    cconnell_1, Apr 17, 2008
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  2. cconnell_1

    Trendkill Guest

    If I had to guess, the switch is not going to send the same frame to
    both ports, else there is no point of an etherchannel (it could then
    only go at the speed of a single port). Therefore, one port has to be
    the first port which traffic is sent, at which time its alternated or
    goes to the second port at a certain utilization. I would guess that
    has something to do with default port...but again...just guessing.
    Would need to read up on
    Trendkill, Apr 18, 2008
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  3. cconnell_1

    News Reader Guest

    "The default port is used to transmit traffic, such as Spanning Tree
    Protocol (STP), multicasts, and unknown unicasts. The default port can
    be identified from the output of the command show etherchannel summary
    by a notation of d."

    Best Regards,
    News Reader
    News Reader, Apr 18, 2008
  4. cconnell_1

    cconnell_1 Guest

    Thats good to know. One thing I have noticed is that the default port
    can change sometimes from 3-4 (if i reset the switch or change the
    config) but mostly stays on 3, not sure if this matters. The nortel
    side refers to this default port on the cisco as "attached
    aggreagator" Im not sure what this means though - any ideas?
    cconnell_1, Apr 18, 2008
  5. cconnell_1

    News Reader Guest

    No, my contribution was limited to finding you some literature ;>) ,
    since you stated "i cant find it in any books".

    Other posters will have more familiarity with this subject than moi.

    Best Regards,
    News Reader
    News Reader, Apr 18, 2008
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