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Find IP based on switchport if arp table is not populated with IP

news2010a
Level 3
Level 3

Hi, my goal is to find out which device IP address is connected to port f0/10. Here is what I have done:

sw#show mac-address-table

Mac Address Table

-------------------------------------------

Vlan Mac Address Type Ports

---- ----------- -------- -----

4 001a.dd75.3e70 DYNAMIC Fa0/10

4 001x.dd75.3deb DYNAMIC Fa0/11

4 0022.1cd4.cd30 DYNAMIC Fa0/9

sw#show arp | i 001a

Nothing is listed, 'show arp' lists no mac address and IP associated with port f0/10.

Question:

Is there any benign way to trigger device connected to f0/10 port to update arp (and resolve IP) so that I can identify

the respective IP address?

1 Accepted Solution

Accepted Solutions

Jon Marshall
Hall of Fame
Hall of Fame

Marlon

The device that you need to run the "sh arp" command is the device that is routing for the vlan. So is the switch you are on in your example a L3 switch ?. If not you need to log on to the L3 device that routes the client vlan and run your arp there.

If it a L3 switch then just ping the device.

Jon

View solution in original post

2 Replies 2

Jon Marshall
Hall of Fame
Hall of Fame

Marlon

The device that you need to run the "sh arp" command is the device that is routing for the vlan. So is the switch you are on in your example a L3 switch ?. If not you need to log on to the L3 device that routes the client vlan and run your arp there.

If it a L3 switch then just ping the device.

Jon

Oh, my bad. That is it.

Thanks!!

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