Re: Joel Jaeggli's Discuss on draft-ietf-6man-ext-transmit-04: (with DISCUSS and COMMENT)

[Brian E Carpenter <[e-mail]>]

On 08/10/2013 20:19, Joel Jaeggli wrote:
...
> ----------------------------------------------------------------------
> DISCUSS:
> ----------------------------------------------------------------------
> 
> This is a dicuss because I'd like to see if I'm in the rough in this.
> 
> Devices generally considered to be IP routers in fact are able to or find
> it necessary to forward on the basis of headers other than the IP header
> e.g. the transport header. By the definition applied in the problem
> statement all ipv6 capable routers in the internet that  I'm aware are or
> are capable of being middleboxes. 

IMHO, yes, if a box is taking a forwarding decision on the basis of anything
other than the first 40 bytes of an IPv6 header, then it's a middlebox
as far as this draft is concerned. Any such box is not a "straightforward IP
router".

In the process of working on the draft I have actually corresponded briefly
with Steve Deering, and I'm pretty sure he would agree with me (with
added expletives).

> I would welcome the existence proof of an ipv6 capable router which is
> not capable of being a middlebox by the definition applied in the problem
> statement.
> 
> I'm not sure that's a glaring flaw in the document but it certainly is
> with our vocabulary around taxonomy if true.
> 
> 
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> COMMENT:
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> 
> If you need to find the transport header due to configured policy and you
> can't due to being unable to parse the extensions chain your configured
> action will be to drop. That perhaps weasels it's way through section 2.1
> requirements but it's still quite ugly.

Yes, and it's the reason that the Internet is mainly opaque to IPv6
extensions headers today.

    Brian