Subject: RE: [dhcwg] Ambiguity in RFC 2131 (pages 37 & 38)

From: Soumava Das <[email-masked]>
Date: Mon, 8 Aug 2005 22:12:45 -0700

Thanks for the clarification. I know that "sname and server-identifier are
unrelated". I mentioned it to indicate that the 'options' field cannot be
empty. And, yes, we also need to send the DHCP message type option. So, the
example was irrelevant.

Another point is that I did not get is why "sname would only ever be filled
in by the DHCP server, never by the client, and the same is true for file."
RFC 2131 page 23 last paragraph indicates that options in a DHCP message
might extend into the 'sname' and 'file' fields. Nowhere in the RFC had I
found anything which indicates that only servers might use the 'option
overload' option. In case clients can use the 'option overload' option, then
the client might fill in the 'sname' and 'file' fields also.

Can you clarify?

Regards,
Soumava

-----Original Message-----
From: Ted Lemon [mailto:[email-masked]] 
Sent: Monday, August 08, 2005 10:04 PM
To: Soumava Das
Cc: [email-masked]
Subject: Re: [dhcwg] Ambiguity in RFC 2131 (pages 37 & 38)

sname and server-identifier are unrelated: sname is a field in the  
fixed portion of the DHCP packet, and server-identifier is a DHCP  
option, which goes in the free-form option section of the packet.    
sname would only ever be filled in by the DHCP server, never by the  
client, and the same is true for file.

You are right though that the RFC is incorrect in claiming that the  
options field is unused - obviously you can't even say what type of  
DHCP packet you're sending if you don't send any options, since the  
dhcp message type option goes in the options field.

On Aug 8, 2005, at 2:37 AM, Soumava Das wrote:

>             I noticed a possible ambiguity in RFC 2131. In page 37,  
> for DHCPDECLINE/DHCPRELEASE, it is mentioned that 'sname', 'file',  
> and 'options' are (unused). However, in page 38, it is mentioned  
> that 'Server identifier' option is MUST, 'Message' is SHOULD, etc.  
> I feel that the two pages contradict each other.

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From: Ted Lemon <[email-masked]>
Date: Tue, 9 Aug 2005 08:46:02 -0400

> the client might fill in the 'sname' and 'file' fields also.

Of course a client might overload into sname and file, but it's never  
going to send an *actual* server name or filename.   That's all I meant.