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Community Member

Port Number

Hi

I am sorry for my question as it is too simple

Q. what command can make me find the port no. of multilayer switch which has as specific IP add (eg. 172.12.x.x)connected to it

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Port Number

Correct, the device that is connected.

11 REPLIES
Blue

Re: Port Number

What do you mean "find the port number"?

Port number of what?

Re: Port Number

Hi,

Try this:

show ip interface brief | include 172.12.x.x

Istvan

Blue

Re: Port Number

Istvan:

Now I understood him...lol

Re: Port Number

show arp | i 172.12.x.x

This will show the MAC associated with the IP address. Then to find what port the MAC was learned on-

show mac-address address [mac address]

CORE#sh arp | inc 10.142.3.2

Internet 10.142.3.2 0 000c.5502.1e62 ARPA Vlan423

CORE#

CORE#sh mac-address-table address 000c.5502.1e62

Legend: * - primary entry

age - seconds since last seen

n/a - not available

vlan mac address type learn age ports

------+----------------+--------+-----+----------+--------------------------

Supervisor:

* 423 000c.5502.1e62 dynamic Yes 80 Gi13/13

Here the IP 10.142.3.2 is on port Gi13/13

Hope that helps.

Community Member

Re: Port Number

Hi

This is for the connected device right

regards,

Re: Port Number

Correct, the device that is connected.

Re: Port Number

Here's a write up I did once, hopefully it helps.

https://packetpros.com/cisco_kb/Find_Device.html

Community Member

Re: Port Number

Hi,

Appreciate your reply

does this show the interface's ip address or the connected device ip address

If answer is interface's ip address then how can find the connected device ip address

Blue

Re: Port Number

Why dont you enumerate exactly which information you want?

1.) IP address of the interface.

2.) Neighbor IP address

etc..etc...etc

Community Member

Re: Port Number

Hi,

sorry for the inconvenience

I said connected device to the interface

which means

1. neighbor ip address

Blue

Re: Port Number

To find the interface with a certain IP address:

sho ip int brief | in x.x.x.x

To view IP address to MAC address binding (ARP):

show ip arp x.x.x.x

To view connected neighbor:

"sho cdp nei"

OK?

Victor

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