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Author Topic: How can I find out what port number a device is patched into if I have the IP?  (Read 11298 times)

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Offline Adam@fullymeshed.it

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Hi All

I have recently been getting my hands dirty with some 5520 stacks and this is by far the best resource I have found on the net  :)

A fairly basic questions for starters...  If I have the IP address and MAC of a client device and I want to know which port it is patched into in the 5520 stack, what is the easiest way to find it?  Without tracing the cable back to the comms room of course... ;)  I figured ARP cache would be a good place to start but all I can see in there is the links to the core stacks...

Apologies if this is a noob question, your help is greatly appreciated.


Online Flintstone

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Hi Adam and welcome to the forum,

The MAC/FDB forwarding table will indicate which port the MAC address was learned on.


Offline TankII

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Show ip arp.
On L-3 switch or in the management VLAN:

500ENTDRRHERS5698STK-01#show ip arp
                                        IP ARP
IP Address      Age (min) MAC Address       VLAN-Unit/Port/Trunk Flags

-------------------------------------------------------------------------------     84        78:2b:cb:99:06:14 VLAN#674-1/4         D
Total ARP entries : 1
Flags Legend:
S=Static, D=Dynamic, L=Local, B=Broadcast

Offline telecom116

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If you know the MAC address or your ERS is a L2 device:

ERS 5520#show mac-address-table address B4-B0-17-7C-C2-5F
Mac Address Table Aging Time: 300
Number of addresses: 1

   MAC Address    Vid  Source         MAC Address    Vid  Source
----------------- ---- -------     ----------------- ---- -------
B4-B0-17-7C-C2-5F 3114 Port:30

Offline Paul L

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show ip arp is very cool, I actually didn't know that one

but there is also a 3rd way.

enable DHCP snooping. Then look in the binding tables.
ACSS- Avaya Enterprise Routing Switch  #8

Offline Adam@fullymeshed.it

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Hi Guys

Thank you all for the answers.  As my stacks are only running L2, show mac-address-table address <MAC Address>  Works a charm!


Offline stauftm

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I use the show mac-address command all the time on my edge swithces. From time to time I have scenerios where I know the mac-but need to know the IP. So on the core 8600 I can run 'show ip arp info'. This will show me all the latest IP to MAC assignments. I usually run this in putty and log it all and have 'config cli more false' enabled. That way after I run the command I can open the txt file and just search for the mac address and then see its IP.