On Thu, Oct 19, 2006 at 06:53:15PM +0800, Su Thunder wrote :
> I don't think your comment is a problem.

I do think it is.

> Whether a block of memory is payload or an extension header is
> determined by the Next Header value of the immediately preceding
> header,

Yes.

> not whether the extension header is known or unknown.

It certainly is, for if it is unknown, it is considered to not be an
extension header.

> A node should pass an unknown extension header to the next header
> immediately following it, why it regards something unknown as
> something else?

I don't understand the statement. But in any case, an IPv6
implementation will stop processing the packet and return an ICMPv6
error if it ever sees an unknown extension header, because it will think
it is an unknown transport protocol.

That's why new IPv6 options should use the existing extension headers
(Dst, Hop-by-hop, Routing), which are always known, and for which there
are predefined fallback behavior for unknown options (e.g. depending on
the high order bits or the option number).

-- 
Rémi Denis-Courmont
http://www.remlab.net/

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