Port Number

[gurkamal01]

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

[lamav]

What do you mean "find the port number"?

Port number of what?

[Istvan_Rabai]

Hi,

Try this:

show ip interface brief | include 172.12.x.x

Istvan

[lamav]

Istvan:

Now I understood him...lol

[Collin Clark]

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.

[gurkamal01]

Hi

This is for the connected device right

regards,

[Collin Clark · Accepted solution]

Correct, the device that is connected.

[Collin Clark]

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

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

[gurkamal01]

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

[lamav]

Why dont you enumerate exactly which information you want?

1.) IP address of the interface.

2.) Neighbor IP address

etc..etc...etc

[gurkamal01]

Hi,

sorry for the inconvenience

I said connected device to the interface

which means

1. neighbor ip address

[lamav]

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