Two ip address have one mac address in N7K

[wfqk]

Hi In Nexus7k, two ip address have one same mac address in different two port when using command

show ip arp | i x.x.x.x, for example show ip arp | 10.1.1.2 and 10.1.1.3

How does it cause the situation? Thanks

[Mark Malone]

ONE WAY IT CAN HAPPEN SAY IF THE IP SCOPE IS DHCP AND ONE DEVICE GOT A DHCP ADDRESS AND THEN A USER ALSO CAME ALONG AND GAVE ANOTHER DEVICE SAME IP BUT AS STATIC ADDRESS SO SWITCH SEES IT TWICE AS DUP, TRACE THE MAC ADDRESSES AND YOU WILL SEE THE LOCAL MACHINES THEN CHECK WHAT THERE IPS ARE SET AS IT MAY GIVE AN IDEA WAHTS GOING ON

sorry for caps only noticed when it was typed :)

[Deepak Kumar]

Hi,

Mostly i notes the same while a user got ip from DHCP (DHCP SERVER may on switch) and after some time user moved with static ip. Then we can see this issue. 

But it was not generate any issue for me yet. One time i was notes with a AP when I was moved the AP from one management to another management vlan and AP was getting the old ip in new vlan. Then I was manual clear the arp for it. And after that it was working fine.

Regards,

Deepak Kumar

[Richard Burts]

Another way that you could get multiple IP addresses that have the same mac address in the arp table is from proxy arp (or perhaps from arp). If 10.1.1.2 and 10.1.1.3 are both reached through some device and if that device is responding to arp requests for those addresses then both addresses would appear in the arp table and both addresses would show the same mac address.

HTH

Rick

[Deepak Kumar]

Sorry I was missed this point. I am agree with Richard. It is chance if you having any routing device down side the your core switch.
Regards,
Deepak Kumar