DHCP option 82 behavior
crask at telesyn.com
Thu Sep 7 17:59:07 UTC 2006
We have some equipment which is doing DHCP snooping, which means that it
forwards DHCP packets on through to upstream devices within their
originating network. Prior to sending the packets on, they insert
option 82 information. If the packets are received by the DHCP server
on the same logical network, it fails to include the option 82
information in the DHCP replies & acks. Unfortunately, due to the
implementation of DHCP on the network devices, this causes a breakdown
in the process (the box tries to prevent flooding the dhcp replies out
to all user ports for security purposes) as it no longer 'knows' which
port the request came from.
In reading the RFC, it suggests that anytime a DHCP server receives
option 82 information, it should always be contained in the reply or
whatever communication is going back to the client. Does anyone know of
a way to enable the inclusion of option 82 information for a local subnet?
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