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Webcast-Catalyst9k
New Member

Duplicate IPs

Hi,

When two switches have the same IP address what determines which device will respond to pinging or telnetting to the IP address? Thanks

4 REPLIES
Hall of Fame Super Gold

Re: Duplicate IPs

Michael

If two switches have the same IP address (in the same VLAN) as their management address they would complain about it. I am not sure that both switches would be active. And if both switches were active then the one who would respond would be the one whose MAC address was in the destination MAC of the Ethernet header of the ping or telnet packet.

HTH

Rick

Re: Duplicate IPs

its basically an ip address conflict, so when u set the same ip address to second switch, the second switch will not ping or telnet, only the 1st switch which has got the ip address will respond for ur request like ping &telnet.

hope this helps,

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New Member

Re: Duplicate IPs

Thanks for the replies.

If I have the following scenario:

swA <---> swB <---> swC

and swA and swB have the same IP address, will swB have two mac addresses for the same IP address if swA and swB are in different vlans?

Hall of Fame Super Gold

Re: Duplicate IPs

If swA is in one VLAN and swB is in a different VLAN then what is the connection between them? What VLAN is it?

It is certainly not legitimate for the same IP address to be in two VLANs. In essence a VLAN is a subnet so you are asking what if the same address is in two subnets. It does not work for the same subnet to be in two separate and unconnected parts of the network.

HTH

Rick

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