Show IP address of specific port

[Ben_Kessell]

I had a switch "dissapear" from our network but it is still plugged in to the appropriate port. In short, the switch on that port has an IP, internet connectivity and packets can move between our vlans but I cannot ping the switch or the devices it's connected to. If I know the port and MAC, how do I look up it's IP from inside the extreme switch?

[Nholy_Raymundo]

Just a newbie here. But just wanna share some experience. Got the same scenario that i have the MAC-ADDRESS of the device and i wanna know the IP and Vice Versa. I tried to do show iparp on L2 switches but it did not show. So i tried it on our L3 core switch then i got the IP Address that i need and from there got all the information to locate the switch/port where the IP/Mac was connected. I'm still learning and wanna hear if maybe any better than my idea.

[Nholy_Raymundo]

Greetings Sir,

Thank you sir, I will try to look deeper on this additional knowledge 🙂

[Tomasz]

Hello Norlito,

It's good to see people learning about networks. 🙂

IP ARP table is one of the approaches and it is a very good one. It would also work if you had an IP address on your switch and pinging the devices but... it's not the case, right?

When you're dealing with L2 devices they would have to introduce some additional features, as traditionally a switch doesn't care about what's inside an Ethernet frame.
Extreme has the solution! 🙂
It is called the node-alias table.
If you have EXOS device with firmware version 22.2 or newer, you might find this useful: https://documentation.extremenetworks.com/exos_22.5/EXOS_User_Guide_22_5.pdf (Chapter 6).
If you have EOS (ex-Enterasys) device, there is nodealias but for stackables (A/B/C series) you would have to use some SNMP manager application or an NMS system like Extreme Management Center to lookup the contents of relevant MIB. With more capable EOS switches (S/K/N) you can lookup the nodealias table directly on a switch.

Hope that helps.
Regards,
Tomasz

[EtherMAN · Accepted solution]

let me see if we can get a couple of things defined. First on the 800 that "disappeared" how were you managing it? Did you have an ip on that switch you were polling? if so then what does the route look like between your monitoring system and the 800? It has to share an ip to another switch/router somewhere for you to be able to manage it in the first place. If you were managing it from the management only port then the port that is connected to should be in a common broadcast domain/vlan that goes to your router interface or management subnet.. You should be able to look at that arp table and confirm you have an arp entry for the ip of the 800... I dont see how you would not know the ip of a device that you had been monitoring.