subenet-mask option in DHCPACK for DHCPINFORM
David W. Hankins
David_Hankins at isc.org
Mon Jul 23 21:48:37 UTC 2007
On Mon, Jul 23, 2007 at 01:37:22PM -0700, Jane Du (jadu) wrote:
> Actually, the dhcp client we are using doesn't like that the subnet-mask
> option is included in the DHCPACK when it doesn't request it. The vendor
> of the client told us that we need to change the code by not sending the
> option because it doesn't follow the spec. In RFC 2131, the option 1 is
> not a "must" added option in the ACK, right?
It is neither a MUST nor is it a MUST NOT. In fact, servers MAY
provide additional options.
In the context of DHCPINFORM, I think this behaviour is not right,
and we'll fix this in a future release.
In the case of DHCPREQUEST, this behaviour is unfortunately mandatory
to be compatible (and to actually work on the modern Internet).
I'm a little bit disappointed to see a client that throws an error if
it sees an option it doesn't understand. The best thing to do is to
just ignore the option. These sorts of things do happen!
> Do you see any issue if I just change code not to send option 1 when it
> is not requested?
If you don't have any clients with the aforementioned flaw, nothing
will go wrong (for example, if you were working fine with 3.0.x).
> In which version, does ISC server start sending the subnet-mask for the
> ack to request? I don't see such behavior in 3.0.4.
3.1.0. It was incorporated as a new feature since it does change
Ash bugud-gul durbatuluk agh burzum-ishi krimpatul.
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David W. Hankins "If you don't do it right the first time,
Software Engineer you'll just have to do it again."
Internet Systems Consortium, Inc. -- Jack T. Hankins
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