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

[joel jaeggli <[e-mail]>]

On Oct 8, 2013, at 12:06 PM, Brian E Carpenter <[e-mail]> wrote:

> 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).

Right, so there are no IP routers on the internet today and you should update the document accordingly because as it stands now it seems to presume their existence.

> 
>> 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.
>> 
>> 
>> ----------------------------------------------------------------------
>> COMMENT:
>> ----------------------------------------------------------------------
>> 
>> 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
>