help-cfengine
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Package management, multicast, and a Newbie question :)


From: Systems Administrator
Subject: Re: Package management, multicast, and a Newbie question :)
Date: Tue, 23 Sep 2003 09:07:12 +1000 (EST)

On Mon, 22 Sep 2003, Chris (Ducky) Chapin wrote:

>
>
> On Mon, 22 Sep 2003, Systems Administrator wrote:
>
> > > I'm interested in technologies like this because we've got more than 2200
> > > centrally managed unix hosts that need access to roughly 100M of
> > > configuration and binary data. They range from desktops to lab machines,
> > > and with generic compute servers definately in the minority.
> >
> >     Wouldn't this be better done as a multicast?
>
> Multicast takes care of getting packets to lots of hosts, mostly streaming
> since it's UDP.  Unfortunately for multicast, it's absolutely required
> that files used for configuration are guaranteed to get there, something
> better for TCP unless you build a protocol on top of udp to add the
> reliability. And then I don't think a multicast system would work too well
> with hosts requesting resends. =)  Resends could be done out of band and
> the multicast would just take care of the bulk of data, but this already
> reaks of trying to shoehorn functionality into the wrong technology.

http://www.globecom.net/ietf/draft/draft-miller-mftp-spec-03.html

        There are a variety of protocols which do this (one example
above), but I don't know much about any of them.  If I recall, some of
them have OOB resends, and others have all the machines request resends,
and then it does one of the following (I forget):
1.      Resends the ones for the least dropping machines first (so they
        can finish their transfer and get off the multicast), OR
2.      Resends the most requested one first, hoping that some machines
        will be able to get off the multicast by them doing this.

        The smart thing, I guess, would be to rewrite multicast so that,
for specially marked IP packets, each host is responsible for ensuring
that it gets to the next.  Hmm.  Does IPv6 have this somewhere?

        :)

--
Tim Nelson
Systems Administrator
Sunet Internet
Tel: +61 3 5241 1155
Fax: +61 3 5241 6187
Web: http://www.sunet.com.au/
Email: sysadmin@sunet.com.au






reply via email to

[Prev in Thread] Current Thread [Next in Thread]