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how to find a port number

 
 
dan_fleming99@hotmail.com
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      06-25-2007
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?

 
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Trendkill
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      06-25-2007
On Jun 25, 10:03 am, (E-Mail Removed) 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.

 
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briggs@encompasserve.org
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      06-25-2007
In article <(E-Mail Removed) .com>, Trendkill <(E-Mail Removed)> writes:
> On Jun 25, 10:03 am, (E-Mail Removed) 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"

 
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Trendkill
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      06-25-2007
On Jun 25, 11:35 am, (E-Mail Removed) wrote:
> In article <(E-Mail Removed) .com>, Trendkill <(E-Mail Removed)> writes:
>
> > On Jun 25, 10:03 am, (E-Mail Removed) 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.

 
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dan_fleming99@hotmail.com
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      06-26-2007
Cheers guys!

I'll give it ago later on!

 
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dan_fleming99@hotmail.com
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      06-26-2007
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



 
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Trendkill
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      06-26-2007
On Jun 26, 5:45 am, (E-Mail Removed) 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.

 
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