[Sugar-devel] Notes on service discovery XS/XO

pgf at laptop.org pgf at laptop.org
Mon Apr 20 10:29:48 EDT 2009

martin wrote:
 > On Mon, Apr 20, 2009 at 3:53 PM, Jonas Smedegaard <dr at jones.dk> wrote:
 > > DNS-SD using unicast DNS seems reasonable to me too.
 > If we can do without the avahi gunk, and use it in a way that is not
 > optimised for user driven browsing but for automated selection of
 > services, then it might work.
 > > Looking closer at the RFC, the initial service queries do have an added
 > > overhead in that a layer of indirection is used (not SRV -> A, but
 > > instead PTR -> SRV + TXT -> A).  But standard DNS optimizations apply,
 > > so SOA record should allow clients to preserve bandwidth through
 > > caching.
 > Can we teach dnsmasq to push all the relevant records with the SOA record?
 > > In other words: Install dnsmasq on the XOs, use plain standard DNS
 > > internally and on the wire, setup DNS-SD entries in a standard
 > > nameserver on the XS, and extend Sugar to support DNS-SD.
 > >
 > > I'd be happy to help compose standard BIND9 files, if that is what will
 > > be used on the XS.
 > If we have a dnsmasq resident expert, I rather use your help
 > transitioning to dnsmasq (note - with several bits of weird dhcp
 > rules). There is no upside to BIND and plenty of downsides, starting
 > with the >25MB memory footprint.

i'm a big fan of dnsmasq, but be sure it will fulfill all your
needs before doing too much work on it -- it's not quite a
full-fledged DNS server -- as an example, dnsmasq doesn't support CNAME:

 >  - ask interesting questions

simon kelley (dnsmasq author) is extremely helpful on the dnsmasq
list, btw, so it shouldn't be too hard to get interesting
answers, as well.  :-)

 paul fox, pgf at laptop.org

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