[Babel-users] babel and zeroconf

[Luke Kenneth Casson Leighton]

hi juliusz, thanks very much for responding!

On Tue, May 13, 2008 at 10:34 PM, Juliusz Chroboczek
<Juliusz.Chroboczek at pps.jussieu.fr> wrote:
> > delighted to have accidentally encountered babel.
>
>  Welcome on board.

 thank you :)

>
>  > i was wondering if anyone has had any experience deploying babel
>  > simultaneously with zeroconf (!) on e.g. a truly wireless adhoc
>  > network.
>
>  Zeroconf is a purely link-local protocol -- it doesn't reach beyond
>  the local link.

 ok - that's good to know (and i was kinda expecting it).

 getting proper WAN-wide name registration and defending is _hard_.

 it takes about _three years_ to get it right - as no less than three
of us found out for samba.  (andrew tridgell started nmbd in 1995, i
carried on for about six to eight months and then jeremy took over,
and i think chris hertel then tackled it some years later).

 i did the necessary exploratory reverse-engineering back in 1996 on
nmbd, for samba, to provide full "network neighbourhood"
functionality.  over three years later we found out that rfc1001/1002
is actually an extended (and botched) version of DNS - the packet
formats are literally and absolutely identical, just with some extra
opcodes.

 i just did some research on zeroconf a couple of hours ago: it turns
out _again_ to be an extension of DNS which is very ironic given
people's aversion to NetBIOS and "network neighbourhood" for being so
"chatty" that people hated it with a vengeance and entirely disabled
it, not realising that it was their own blatant misconfiguration that
causes nmbd and windows "network neighbourhood" to have to compensate
for their lack of knowledge on how to properly configure it :)

 so i'm familiar with what a "proper" wide-area-network
automatic-name-configuration-and-defending "thing" should look like...
but...

>  In a mesh network, the notion of link doesn't really
>  exist, so zeroconf will give mixed results.

... this i don't follow.  you're using terms that have specific
meanings with which i'm not yet familiar, and, as it's an area i
really do need to understand, i'd very much appreciate some pointers /
elaboration.

in particular, what does - or doesn't - babel provide for "mesh networks" ?


>  (The same is true of DHCP, by the way, which is why we have developed
>  our own configuration protocol (AHCP).)

 oh?  ooo :)

>  More precisely, zeroconf in a mesh network will only allow you to
>  speak to your neighbours.

 yes.  the "network neighbourhood" protocol uses a central WINS server
(which in the microsoft system is _definitely_ one-only).

so, one of the first things that i did, by about 1998, was create a
"hierarchical" WINS server infrastructure in nmbd.  this
"multi-workgroup" version of samba as i called it was considered
unacceptable by the samba team and was never accepted, despite the
fact that it was first demonstrated in redmond, to microsoft.

ironic.  the P.R. out of the first multi-workgroup PDC to be deployed
on microsoft's internal network being _samba_ not a windows system
would have been amazing, but it was not to be... :)


>  IMHO, the righ solution would be to extend zeroconf to work over
>  a site-local IPv6 prefix, and to extend Babel to route multicast.

 mm? *quizzical*.  i thought ipv6 didn't do multicasting?

>  Let
>  me know if you want to work on the former, and I'll think about the
>  latter.

 ok.

 to let you know: there's a project (awaiting funding... arg) that is
going to need - believe it or not - about *three* separate wireless
networks (in the same device!), all with different characteristics and
capabilities.  the lowest speed network is a digital radio modem, with
something like a 10 mile range (with TCP/IP on it).  the other ones we
have yet to specify but candidates include GPRS/EDGE or maybe 3G, and
WIMAX or some other adhoc high speed networking.

please don't ask why all that's needed :)

so i am suddenly extreemely interested in decent and versatile routing
software that can help here!  fallback to the long-range radio modem
is of course the absolute last resort but ultimately the applications
should ... just ... not care in the slightest bit about what's
happening, because the users certainly won't.

so i will have - some time in the next few weeks - suddenly plenty of
time on my hands to focus on this.  and perhaps some funding available
too.

l.