NEXUS 7000 vPC loop when enabling DHCP feature

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Mar 16th, 2010
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Hello All,

I'm setting up a new data center with two Nexus 7000 and one Nexus 5000 . The 5000 is connected to both 7000s using a vPC ( all is done by the book and the vPC is working very well).

If I enable any VLAN interface on the 5000 then I start getting a duplicate IP address warning ( the IP address of the VLAN interface ) :

%ARP-2-DUP_SRC_IP:  arp [2783]  Source address of packet received from 000d.ecf2.8dbc on Vlan90(port-channel4043) is duplicate of local

It seems that the gratuitous arp requests for the local address are getting looped back to the 5000 over the vPC !!

I noticed that the issue only happens when the DHCP feature is enabled on the Nexus 7000s ...

Any help is really appreciated ....

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Jerry Ye Tue, 03/16/2010 - 13:43
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What version of NXOS are you running?



Jerry Ye Tue, 03/16/2010 - 14:06
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Sound like you are hitting bug ID CSCsx69941. The fix will be in 4.1(5) or 4.2(1).



mrahman71 Tue, 03/16/2010 - 14:26
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Upgrading to 4.2 (4) fixed the issue ... Thank you Jerry for your help


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