Re: [dhcwg] DHCPv6: Canonical way to handle an unknown option

[Bud Millwood <budm at weird-solutions.com>]

On Tuesday 02 June 2009, Gabor Retvari wrote:
> Dear all,
>
> What is the best way to handle a DHCPv6 message that contains an unknown
> DHCPv6 option? Should an implementation drop the message as a whole, once
> it encounters an unknown option in it, or should it drop only the option
> and carry on processing the rest of the message that it can make sense of?
> (It seems to me that wide-dhcp, for instance, implements the latter
> behavior.)
>
> Could any one provide me with a pointer on the recommended way to handle
> unknown options in DHCPv6 implementations?

The de-facto standard for adding new options to DHCPv4 has always been that if 
a sender transmits an option, and the reply does not contain the option (or 
does not contain any explicit reply to that option), the server does not 
understand the option. The sender can then alter its behavior accordingly.

This long-time standard behavior implies that it is the norm for a server to 
drop unknown options (from the sender's perspective; what you do with them 
internally is your business). I highly doubt that this group would recommend 
any other behavior for DHCPv6.

- Bud

Bud Millwood
Weird Solutions, Inc.
http://www.weird-solutions.com
tel: +46 8 758 3700
fax: +46 8 758 3687