invalid DISCOVER packet - update

David W. Hankins David_Hankins at
Tue Apr 10 16:55:33 UTC 2007

On Tue, Apr 10, 2007 at 11:17:32AM -0500, Duane Cox wrote:
> Would you agree to that?  That's not how I read the RFC...

Well, no, I read the RFC the same way, so I wouldn't agree
with your relay vendor.

The RFC discusses only the client<->server model...not the
client<->relay<->server model (at least, not explicitly).

Because the minimum IP MTU is 576, I think a relay is justified
in not accepting larger packets...if their MTU is really 576.

I would say that a relay needs to support DHCP packets up to
their MTU size.

But I also would say it is terribly unfair of the Cisco device
to send a 604 byte packet when the trailing bytes are all zero.

ISC Training!  training at
Washington DC area, April 16-20 2007.  DNS & BIND, DDNS & DHCP.
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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