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I am trying to get which IP is connected to which port.  I know I can get the mac address for each port by using sh mac-address.

When I do a sh arp I only get 3 entries.  This switch is connected to the core which is also a stack of 4 HP 2920's (connected via 2 10GB links config as LACP)

If the switch is deployed as layer 2, that is expected as you will see ARP entries only where you have a layer 3 (routing) instance for the subnet. So you should be able to get the IP to mac mapping where you route the traffic, which is probably the core or a firewall.

 

One way to get IP information on layer 2 ports is to enable port-security, so 802.1X and/or MAC authentication. In that case, the command 'show port-access clients' will show more information, including the IP.

 

If the clients are dhcp clients, enabling the dhcp snooping option may provide ip-mac mapping as well for those clients.

Go to the Core and run show arp vlan [id] and from the output identify and note the MAC address of the IP you are looking for. Then come back to the switch where this IP is connected and run show mac-address vlan [id], the result will give you the mac address and the port details. I usually do this when helpdesk asks me to find the port of a specific IP address. Hope this helps.

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Bharath Kumar Gajula
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Original Message:
Sent: Mar 20, 2019 04:18 PM
From: David Steinberg
Subject: Show IP address for ports HP2920 switch

I am trying to get which IP is connected to which port.  I know I can get the mac address for each port by using sh mac-address.

When I do a sh arp I only get 3 entries.  This switch is connected to the core which is also a stack of 4 HP 2920's (connected via 2 10GB links config as LACP)