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

[Dave Taht <[e-mail]>]

On Sun, Dec 21, 2014 at 11:44 AM, Juliusz Chroboczek
<[e-mail]> wrote:
>>>> You might also need to combine the features of the gateway with the
>>>> metric(s) of the path to the gateway.
>
>>> I do end-to-end measurements in my mosh implementation, so we should
>>> not have the problem.
>
>> Does this really scale well?
>
> How well do we need it to scale?  Three addresses per host?  A dozen?
> A hundred?  (Per host, mind you -- not per router.)
>
> The probes Matthieu's code is sending are less than 90 bytes each.  This
> means that if the client and the server have three addresses each, each
> probing episode consists of a burst of 9 packets totalling less than one
> full Ethernet frame.  (18 if you count the replies.)
>
> On the other hand, if we end up having hundreds of addresses on every
> host, the strategy will need to be rethought.  Dave is currently playing
> with a network where each host has 10 addresses of different kinds, and
> he's trying to work out heuristics to limit the number of probes.  I'd
> personally prefer to gather some empirical data before we start optimising
> things.

That has been a very long, and interesting, private thread, and I should
summarize here but Ive been awake 24 hours hacking on this -

The particular test server I have is an 8 port rangeley router with 36
projected ip
addresses, connected to a test client with 12, which is rather a lot
of connections to
probe and sort through. Amazingly mosh-multipath, does, indeed, work
in this case.

(And mosh is the greatest thing since sliced bread already for a
beleagured sysadmin type that endures
frequent mobility events and periods of disconnectivity!)

...

I have been also hacking on odhcpd and hnetd and a few other end
products of this wg to see how far they are along.  (my testbed plan
was to have 5 source specific gateways working across about 70
routers)

I have had to file multiple bugs on all the dhcpv6 clients, and be
annoyed at comcast for sending ras under a minute intervals,
thoroughly break ubuntu and openwrt,  and work around various other
problems, but overall things are much better than they were last
month, and almost as fast as I file bugs, they get fixed.

see various open and closed bugs on https://github.com/sbyx/hnetd/issues/24
https://github.com/sbyx/odhcp6c/issues/27

and rants about it all and some of the tools I have been using on my g+

https://plus.google.com/u/0/107942175615993706558/posts/CsGyyJspjVK

But everything homenet-ish is looking very promising. I guess I have
to go compile a couple boxes with mptcp support soon.

so far babel has been dealing with failing over default gateways going
up and down and source specific routes through a very complex network
beautifully, even though only 1/3 the network is source specific
enabled. (and updating the parts remaining involves climbing a lot of
trees. in the rain. Preferably with a totally baked version of openwrt
chaos calmer)

> -- Juliusz
>
>



-- 
Dave Täht

thttp://www.bufferbloat.net/projects/bloat/wiki/Upcoming_Talks