Re: [dhcwg] RFC2131 - option multiple times - which ones ?

["David W. Hankins" <[e-mail]>]

On Fri, Mar 11, 2005 at 10:12:15AM +0100, Grubmair Peter wrote:
> I interpreted it like this:
>   The rule is, that a specific option may appear only once in
>   a dhcp message.
>   The exception from this rule is, that the option document (RFC2132 or
> other)
>   tells , that the option may appear multiple times.
>   Then the multiple instances of the option have to be concatenated into
>   one instance before interpretation.

That is a perfectly reasonable interpretation considering the poor choice of
words in that section of the RFC, but not what I judge to be the intent.

Here's the way I wish it read:

	Any option MUST only appear once after processing.  During
	processing, if multiple instances of an option are encountered,
	they MUST be concatenated to form one option data block before
	the option's contents are evaluated.

>   I think all options using charackter strings or lists (of ip addresses)
> may
>   be split during send and have to be concatenated during reception
>  , but RFC2132 tells nothing about this.

The content of the option is unimportant at this layer of processing.  Any
option with a length greater than one MAY be split up.  Realistically
clients and servers only do this if option data is longer than 255 bytes,
or if they need to perform option overloading.

-- 
David W. Hankins		"If you don't do it right the first time,
Operations Engineer			you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins

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