Re: [homenet] sorting out the right ipv6 addr to choose and name in a source specific world

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

On 19/12/2014 13:47, joel jaeggli wrote:
> On 12/18/14 4:39 PM, Jim Gettys wrote:
>>
>>
>> On Thu, Dec 18, 2014 at 7:19 PM, Brian E Carpenter
>> <[e-mail] <mailto:[e-mail]>> wrote:
>>
>>     On 19/12/2014 11:22, Juliusz Chroboczek wrote:
>>     > Shouldn't we reduce the amount of cross-posting at some point?
>>     >
>>     >>> mptcp, I'm told, is likely to show up in Apple and Google
>>     products and
>>     >>> infrastructure, and my idea (and many others) is that you
>>     don't always have
>>     >>> to pick the perfect address for the SYN, just one that works,
>>     but rather one
>>     >>> can add better addresses as one discovers them.
>>     >
>>     >> But bad luck if you need UDP.
>>     >
>>     >> Some form of intelligent probing does seem to be the answer,
>>     >
>>     > I'd like to attract your attention to the work that Matthieu
>>     Boutier has
>>     > been doing on mosh, Keith Winstein's UDP-based ssh replacement:
>>     >
>>     >   http://comments.gmane.org/gmane.network.mosh.devel/749
>>     >
>>     > Boutier's version of mosh builds connections across all
>>     source/destination
>>     > pairs, and picks the one with lowest RTT.
>>
>>     Sounds interesting. In the ideal world, that would be a pluggable
>>     policy algorithm. Lowest RTT may not always be the best choice.
>>     NAROS* suggested distributing policy from a single source, for
>>     example.
>>
>>     The point about shim6, of course, is that allows you to change
>>     horses in midstream without bothering the transport layer.
>>     It's a real shame we don't know how to deploy it, especially
>>     for homenets where nobody manages the routing policy.
>>
>>
>> ​
>> What were the problems with getting shim6 deployed? 
>>
> need a time machine
> 
> https://www.nanog.org/meetings/nanog35/presentations/schiller.pdf

Well, let's not start that argument again. Shim6 was never intended to
address operator's concerns, so it didn't. The real world problems are
these:

1. Most firewalls drop packets containing the shim6 extension header.

2. When shim6 switches addresses, the packets get a big bigger and
that might reveal a PMTUD problem.

3. Absent SADR in the exit router, shim6 has a high chance of falling
victim to BCP38 filtering.

More details:
H. Naderi & B.E. Carpenter, Putting SHIM6 into Practice,
Australasian Telecommunication Networks and Applications Conference
(ATNAC 2014),
Melbourne (November 2014).
https://www.cs.auckland.ac.nz/~brian/Shim6-ATNAC14-subm.pdf

    Brian

> 
>> There appear to have been 
>> ​a Linux implementation, and if the idea now has merit, that is enough
>> of the market (which is very responsive) ​
>> ​to get significant deployment, and to do so quickly. (codel/fq_codel
>> went from concept to shipping code is under 3 months, with wide test
>> deployment in a year, and now becoming default).  We aren't talking
>> about 5 year product cycles any more.
>>
>> As to policy, the home routers themselves give us a place to enable
>> people to state the policy they want (e.g. only use the LTE upstream
>> if the cheap broadband service is unavailable...).
>>                                     - Jim
>>
>>
>>        Brian
>>
>>     * C. Launois, O. Bonaventure, and M. Lobelle. The NAROS approach
>>     for IPv6
>>     multihoming with traffic engineering. volume 2811 of Lecture Notes in
>>     Computer
>>     Science, pages 112–121. Springer Berlin Heidelberg, 2003.
>>
>>     > It's a work in progress --
>>     > there are multiple versions, and Matthieu has yet to decide which
>>     > implementation he's going to submit for inclusion in mainline mosh.
>>     >
>>     > We hope to write that stuff down when Matthieu has decided which
>>     is the
>>     > "right" version, but I'm not promising any hard deadlines -- we
>>     have a lot
>>     > of stuff that we want to write down.
>>     >
>>     >> but certainly that needs to be generic because we cannot expect
>>     >> all apps developers to reinvent it.
>>     >
>>     > Uh-huh.  But there's only one thing that's worse than
>>     generalising from
>>     > one example -- it's generalising from zero eexamples.
>>     >
>>     >> http://tools.ietf.org/html/draft-naderi-ipv6-probing recently.
>>     >
>>     > I'll have a look, thanks for the pointer.
>>     >
>>     > -- Juliusz
>>     >
>>
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