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Nexus 7K DHCP Snoop errors after adding 2nd dhcp relay address

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force5

ISP
Nov 4, 2004
118
US
Good morning,

We have 2 Nexus 7010's, Nexus-A in our main data center, Nexus-B out in our DR site. They are in a vPC configuration. Our main office has 4 IDF closets (stacks of 3750X), 2 closets upstairs/2 closets downstairs. All clostes are vPC'd to both Nexus'.
Yesterday, I added a 2nd DHCP Relay Address entry on both Nexus' for all 4 of the closet VLANS (112, 122, 132, 142). This relay is only for re-coring our machines across the seperate VLANs so that when we do PXE boot. As soon as I added the 2nd address, I began getting DHCP snoop (3) errors for the 4 closets on Nexus-B.

<Nexus-B-Data %DHCP_SNOOP-3-INVDHCPPKTS: Validation errors while processing DHCP packet received on interface Vlan122 vlan 0 Reason:DHCP length encoding over-flow.. Dropping the packet>

Nexus-A is configured exactly the same but has no errors. The only difference is, is that our server team does not have their UCS servers in a vPC configuration, so they are only located in our data center with Nexus-A. They are choosing to use an Active/Passive architecture and move VM servers as they need to. Nexus-B has all relevant configurations to accomodate their UCS.

The strange this is, I added this same 2nd DHCP relay address a few months ago and never had any issues. However, this time adding it, I see that the 2nd address (10.216.101.xxx) is now on top of the main DHCP server (10.216.110.xxx)

ip dhcp relay address 10.216.101.xxx
ip dhcp relay address 10.216.110.xxx

Do I need to force 10.216.110.xxx to be first on the list? If this is the case, why aren't I seeing this on Nexus-A? Any help would be appreciated!

Regards,

Chad
 
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