Re: [dhcwg] Maximum message size interpretation

Tobin Coziahr <tobin.coziahr@sun.com> Tue, 19 February 2002 12:11 UTC

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Date: Tue, 19 Feb 2002 03:59:42 -0800
From: Tobin Coziahr <tobin.coziahr@sun.com>
Organization: Sun Microsystems
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To: Thomas Narten <narten@us.ibm.com>
CC: Bud Millwood <budm@weird-solutions.com>, DHCP discussion list <dhcwg@ietf.org>
Subject: Re: [dhcwg] Maximum message size interpretation
References: <200202191134.g1JBY4B04586@cichlid.adsl.duke.edu>
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My apologies, you're right.  All of the information I just found on the
subject notes that the minimum value for this option is 576, which along
with the RFC that you quoted shows that I was mistaken.

The Maximum Message Size option DOES include the IP and UDP headers.

Thanks for the correction, Thomas.

-Tobin

Thomas Narten wrote:
> 
> > The Maximum Message Size option is also known as the "maximum DHCP
> > message size" option (See RFC 2131, page 9-10).  This ONLY refers to the
> > size of the DHCP packet itself, without the IP and UDP headers.  The
> > point of the option is to let servers use messages larger than 548
> > bytes, which is the default max.
> 
> > So no, don't subtract the header size.
> 
> Hmm. That's not what draft-ietf-dhc-csr-06.txt says:
> 
> >    stack is capable of reassembling fragmented IP datagrams.  In this
> >    case, the client SHOULD set the value of this option to at least
> >    the MTU of the interface that the client is configuring.   The
> >    client MAY set the value of this option higher, up to the size of
> >    the largest UDP packet it is prepared to accept. (Note that the
> >    value specified in the Maximum DHCP Message Size option is the
> >    total maximum packet size, including IP and UDP headers.)
> 
> Is the above text correct?
> 
> Thomas
> 
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-- 
Tobin Coziahr			650-786-7118 (x87118)
Solaris Networking		tobin.coziahr@sun.com
Sun Microsystems

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