How do I find the IP of the SWITCH that I'm connected to?

[DougK62]

Like the title says, we apparently screwed up a while ago when assigning an IP to a switch. The switch works happily, but we don't know the IP to log into it. Is there an easy way to discover this? I really don't want to hook up to it with a serial cable and monkey with it like that. Is there some sort of (hopefully free) utility that can report this information?

Thanks.

 

[nweaver]

use a ping tool such as angryip to find all ip's, and eliminate the ip's you know, and look at the macs for the switch vendor's ID

 

[TC10284]

Do you have a router or another switch you can telnet into or console into? Are these Cisco devices?

You could also use Look@LAN to scan the IP range you think it's in and do similar to what nweaver said.

 

[kt]

Just using a serial cable would've been faster. What's so bothersome about using a serial cable anyway?

 

[skyking]

Originally posted by: kt
Just using a serial cable would've been faster. What's so bothersome about using a serial cable anyway?

QFT. Trouble is, hardly anyone makes a lappy with a serial port these days, and you have to add a converter dongle to <the already too full> laptop bag.
I scored a D610 of fs/ft because it was the last Dell model to have a serial port native.
None of the x20 series have one.

 

[avi85]

Originally posted by: kt
Just using a serial cable would've been faster. What's so bothersome about using a serial cable anyway?

ewwww! serial! 😛

 

[Nothinman]

I really don't want to hook up to it with a serial cable and monkey with it like that. Is there some sort of (hopefully free) utility that can report this information?

If you don't want to mess with a serial cable, maybe you're not the right person to be managing those switches? But switching is at layer 2 and IP at layer 3 so there's no direct way to figure out what IP the switch that you're plugged into has.

 

[spidey07]

Originally posted by: Nothinman

I really don't want to hook up to it with a serial cable and monkey with it like that. Is there some sort of (hopefully free) utility that can report this information?

If you don't want to mess with a serial cable, maybe you're not the right person to be managing those switches? But switching is at layer 2 and IP at layer 3 so there's no direct way to figure out what IP the switch that you're plugged into has.

use packet capture to get the spanning-tree bpdus.

look at bridge identifier (will have priority.mac address of switch)

run ping sweep of subnet

match switch mac to ip address

Or, if it's a cisco switch just capture the cisco discovery protocol packets and you'll see the IP in there.

or just plug a serial cable to it like you're supposed to. 😉

 

[ForumMaster]

a switch doesn't have an ip. only routers do. a switch is a lvl 2 device that operates with MAC addresses. you will need a cable to interface with it.

 

[Cloud Strife]

Originally posted by: ForumMaster
a switch doesn't have an ip. only routers do. a switch is a lvl 2 device that operates with MAC addresses. you will need a cable to interface with it.

If it has a serial cable connector on the switch, it's probably a managed switch, which will have an IP address.

 

[TC10284]

Managed switches can be assigned an IP.


As for the original question, if it is a Cisco device, and you can telnet into a Cisco router or switch that is directly connected to that switch, you should be able to do a show cdp neighbors detail for directly connected Cisco devices, with Layer 3 information.

 

[spidey07]

Originally posted by: ForumMaster
a switch doesn't have an ip. only routers do. a switch is a lvl 2 device that operates with MAC addresses. you will need a cable to interface with it.

most switches you can just attached to a network and they'll get an IP via DHCP.

switches absolutely have IP addresses. Heck I'm staring at one right now that has about 150 ip addresses.

 

[nweaver]

Originally posted by: avi85

Originally posted by: kt
Just using a serial cable would've been faster. What's so bothersome about using a serial cable anyway?

ewwww! serial! 😛

A serial port is a must have item on a laptop imho, I use mine every day. I just used it to install Debian on a headless sun box, and to manage a cisco switch that didn't have an ip. So dang much more usefull then a stupid parallel port, and I already have enough USB ports.


I have a D810, like the D610. It's been a decent one.

 

[spidey07]

true that.

without a serial port you are utterly usless in a data center.

 

[NesuD]

Originally posted by: TC10284

Managed switches can be assigned an IP.


As for the original question, if it is a Cisco device, and you can telnet into a Cisco router or switch that is directly connected to that switch, you should be able to do a show cdp neighbors detail for directly connected Cisco devices, with Layer 3 information.

exactly!