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Switches, Hubs, and Modems
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dhcp snooping incorrectly drops offer: "address already assigned"

Occasional Visitor

dhcp snooping incorrectly drops offer: "address already assigned"



HP53xx switch K.15.02.0005, with dhcp-snooping enabled, isc dhcp server 3.1.1 in failover configuration

a client was not able to get an address, and the switch was complaining that:


<date> <switch IP> 02684 dhcp-snoop:  AM1: backplane: Drop offer from <server IP> of <offered IP> because the address is already assigned to another client


from the dhcp server log, we have confirmation the a legitimate server, configured as such in the switch dhcp-snooping, was offering the <offered IP>, but the same IP had hot even been offered (DHCPDISCOVER/DHCPOFFER) to any other client previously, let alone assigned (DHCPREQUEST/DHCPACK).

dropping the packet seems then incorrect.


we found no reference to that message in the documentation. what is its exact meaning?

is is possible to disable this check only without disabling dhcp-snooping globally?



best regards


MAtteo Valsasna

Università degli Studi dell'Insubria

Ulrich Saur

Re: dhcp snooping incorrectly drops offer: "address already assigned"

Hi Matteo,


try 'no dhcp-snooping verify mac', this should help.

Please, also, use another (newer) Firmware Release, if upgrading is possible, the one you use is a 'dangerous' one...