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How to recover Switch IP ?

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7 replies

by shayad

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We have 24 port 10/100 Mbps managed Switch. Console port is not working now. Earlier Administrator defined some IP address to this switch which is not known to anyone.
Now as he has quit so we need to recover that IP.
How can I recover the IP of this switch? Someone told me I can use sniffer for this...Will it work...How to use sniffer.

Remember, IP defined on switch is not of our present network range of address...

7 replies

by budthegrey

If the hardware MAC address is on the switch -- many manufacturers do that -- you might be able to use a tool ike ARP or some such to determine the IP address of the unit.

by wwn

If you are on a Cisco network try this. From the Cisco Router use the "show cdp neighbor" command to see your attached Cisco switch. If there is no hostname on the switch you will get it's MAC address. To get the IP address in the switch use the "show cdp entry *" command. Then put a secondary (or subinterface)on the router interface that connects to the switch using a compatible IP address. Should be able to PING it now. You could TELNET to it also to configure the switch, but it may require apassword.

by shayad

I can't login to switch as I dont have the IP address...I even can't login via console as it is faulty

by carsten.holfelder

I found that Fluke network inspector finds such ip addresses. Once found you can configure a second ip address on the network card of your computer and then telnet into the switch.

by ckilday

Question: who manufactured the switch? Have you gone to their website and looked for troubleshooting tips? Some switches have power-on reset procedures which returns the address to a default IP that you can telnet to. If this is the case, you want to do this after hours because it will disrupt your regular network.

Do you have another switch on the same network that you can access? Sometimes a network admin will create a separate network to control switches and routers, but to dimplify his job, he will put all the switches and routers on the SAME network. Look at the configuration of the devices you can access. You may find something like this...router - 192.168.1.1, switch - 192.168.1.2 and so on. If you find a number missing (out of sequence), that could be it. You can try to ping or telnet other numbers in the series.

Finally, if the previous admin created a separate network to control switches and routers, this has to be supported by the router or its traffic willnot pass. Look at the router configuration for an interface with two ip networks on it, or for a VLAN, if you have something like a large cisco switch with an RSM.

Best wishes!

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