compaq loopback cables ?

Discussion in 'Cisco' started by tg, Oct 22, 2008.

  1. tg

    tg Guest

    I recently bought a cisco module NM-16ESW (16 port switch) and when it
    arrived all the sockets had little 2 inch cables sticking out of them.
    These cables were sealed at the end and some were labelled:
    Compaq
    PN 317463-001
    SPARE
    317465-001
    ID 10036233 REV. C
    I saw on google they are called 'Compaq loopback cables' and I saw
    several places that advertised them for sale but I don't know what
    they're for.
    does anyone know what the function of these is? thanks for any advice.
     
    tg, Oct 22, 2008
    #1
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  2. Re: compaq loopback cables ?

    "tg" <> writes:
    >I recently bought a cisco module NM-16ESW (16 port switch) and when it
    >arrived all the sockets had little 2 inch cables sticking out of them.
    >These cables were sealed at the end and some were labelled:
    >Compaq
    >PN 317463-001
    >SPARE
    >317465-001
    >ID 10036233 REV. C
    >I saw on google they are called 'Compaq loopback cables' and I saw
    >several places that advertised them for sale but I don't know what
    >they're for.
    >does anyone know what the function of these is? thanks for any advice.


    Guess they wanted to get rid of them.. :)

    I don't find them all that useful, but they just loop the transmits
    back out to the receives for the port, so you can test that everything
    looks good on the port and comes up and tests out for the switch.

    Ie. make one here.

    http://www.tikkiweb.net/loopback

    Much like a T1 loopback connector which will loop the T1 transmit back
    to receive so you can test the wire and find faults, you can test each
    port with the ethernet loopback plugged in.
     
    Doug McIntyre, Oct 22, 2008
    #2
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  3. tg

    Guest

    Re: compaq loopback cables ?

    On 22 Oct, 22:46, "tg" <> wrote:
    > I recently bought a cisco module NM-16ESW (16 port switch) and when it
    > arrived all the sockets had little 2 inch cables sticking out of them.
    > These cables were sealed at the end and some were labelled:
    > Compaq
    > PN 317463-001
    > SPARE
    > 317465-001
    > ID 10036233 REV. C
    > I saw on google they are called 'Compaq loopback cables' and I saw
    > several places that advertised them for sale but I don't know what
    > they're for.
    > does anyone know what the function of these is? thanks for any advice.


    Without researching the exact devices it seems likely
    that they are Ethernet loopback plugs.

    I have not read these but the GOOGLE heading seems
    to suggest that they will be of interest.

    www.juniper.net/techpubs/software/nog/nog-interfaces/html/fe-ge-loopback25.html

    www.juniper.net/techpubs/software/nog/nog-interfaces/download/fe-ge-loopback2.pdf
    "Use Loopback Testing for Fast Ethernet and
    Gigabit Ethernet Interfaces"

    They will bring the port UP if it is enabled.

    Any packets sent out will be sent back in.

    If STP is enabled then of course the ports
    will transition to STP blocking state.
    Unless of course portfast is enabled and
    a broadcast storm overwhelms the
    CPU first.
     
    , Oct 22, 2008
    #3
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