how to find a port number

Discussion in 'Cisco' started by dan_fleming99@hotmail.com, Jun 25, 2007.

  1. Guest

    Does anyone know if it is possible to find a port number of a switch
    from a IP or MAC address? If that makes sense?
     
    , Jun 25, 2007
    #1
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  2. Trendkill Guest

    On Jun 25, 10:03 am, wrote:
    > Does anyone know if it is possible to find a port number of a switch
    > from a IP or MAC address? If that makes sense?


    1. On router that owns the subnet: show arp | include a.b.c.d

    2. Then take the resulting mac from the above command, put in format
    aa-bb-cc-dd-ee-ff

    3. Go to core switch: show cam aa-bb-cc-dd-ee-ff

    4. Should tell you the port it is on, including if it is off a
    trunk. If it is off a trunk, do show cdp neigh <mod/port> detail, and
    telnet to the next switch.

    5. Do task 3 and 4 as necessary till you find the port.

    Note - If it is an IOS based switch, the command is show mac-address-
    table | include <mac> (rather than show cam), but the outcome should
    be similar.
     
    Trendkill, Jun 25, 2007
    #2
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  3. Guest

    In article <>, Trendkill <> writes:
    > On Jun 25, 10:03 am, wrote:
    >> Does anyone know if it is possible to find a port number of a switch
    >> from a IP or MAC address? If that makes sense?

    >
    > 1. On router that owns the subnet: show arp | include a.b.c.d


    The syntax I use is "show ip arp a.b.c.d".


    > 2. Then take the resulting mac from the above command, put in format
    > aa-bb-cc-dd-ee-ff
    >
    > 3. Go to core switch: show cam aa-bb-cc-dd-ee-ff
    >
    > 4. Should tell you the port it is on, including if it is off a
    > trunk. If it is off a trunk, do show cdp neigh <mod/port> detail, and
    > telnet to the next switch.
    >
    > 5. Do task 3 and 4 as necessary till you find the port.
    >
    > Note - If it is an IOS based switch, the command is show mac-address-
    > table | include <mac> (rather than show cam), but the outcome should
    > be similar.


    The syntax I use for IOS is is "show mac-addr addr xxxx.xxxx.xxxx"
     
    , Jun 25, 2007
    #3
  4. Trendkill Guest

    On Jun 25, 11:35 am, wrote:
    > In article <>, Trendkill <> writes:
    >
    > > On Jun 25, 10:03 am, wrote:
    > >> Does anyone know if it is possible to find a port number of a switch
    > >> from a IP or MAC address? If that makes sense?

    >
    > > 1. On router that owns the subnet: show arp | include a.b.c.d

    >
    > The syntax I use is "show ip arp a.b.c.d".
    >
    > > 2. Then take the resulting mac from the above command, put in format
    > > aa-bb-cc-dd-ee-ff

    >
    > > 3. Go to core switch: show cam aa-bb-cc-dd-ee-ff

    >
    > > 4. Should tell you the port it is on, including if it is off a
    > > trunk. If it is off a trunk, do show cdp neigh <mod/port> detail, and
    > > telnet to the next switch.

    >
    > > 5. Do task 3 and 4 as necessary till you find the port.

    >
    > > Note - If it is an IOS based switch, the command is show mac-address-
    > > table | include <mac> (rather than show cam), but the outcome should
    > > be similar.

    >
    > The syntax I use for IOS is is "show mac-addr addr xxxx.xxxx.xxxx"


    Either should work....different abbreviations, syntax, or shortcuts.
     
    Trendkill, Jun 25, 2007
    #4
  5. Guest

    Cheers guys!

    I'll give it ago later on!
     
    , Jun 26, 2007
    #5
  6. Guest

    ive tried the show cam (macaddress) and i get the following stuff come
    up but it doesnt say what port it is plugged into (i dont think it is
    8/8, like it says there) any idas?


    switch> (enable) show cam xx-xx-xx-xx-xx-xx
    * = Static Entry. + = Permanent Entry. # = System Entry. R = Router
    Entry.
    X = Port Security Entry

    VLAN Dest MAC/Route Des [CoS] Destination Ports or VCs /
    [Protocol Type]
    ---- ------------------ -----
    -------------------------------------------
    100 xx-xx-xx-xx-xx-xx 8/8 [ALL]
    Total Matching CAM Entries Displayed = 1
     
    , Jun 26, 2007
    #6
  7. Trendkill Guest

    On Jun 26, 5:45 am, wrote:
    > ive tried the show cam (macaddress) and i get the following stuff come
    > up but it doesnt say what port it is plugged into (i dont think it is
    > 8/8, like it says there) any idas?
    >
    > switch> (enable) show cam xx-xx-xx-xx-xx-xx
    > * = Static Entry. + = Permanent Entry. # = System Entry. R = Router
    > Entry.
    > X = Port Security Entry
    >
    > VLAN Dest MAC/Route Des [CoS] Destination Ports or VCs /
    > [Protocol Type]
    > ---- ------------------ -----
    > -------------------------------------------
    > 100 xx-xx-xx-xx-xx-xx 8/8 [ALL]
    > Total Matching CAM Entries Displayed = 1


    Is 8/8 a trunk? It could be a trunk or uplink to another switch.
    Regardless, it should be right, else your network would not be
    accurate servicing that IP address. What I mean by that is, at layer
    2, the switch relies on its MAC table for frame delivery, and if your
    core has a mac on a port that is not accurate, then traffic will not
    make it correctly.
     
    Trendkill, Jun 26, 2007
    #7
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