Reliable multicast over IP on Linux

Hi,

I want to look at the possibility of using reliable multicast to send
software updates and periodic config/status information to all hosts
on an Ethernet network.

Most of the reliable multicast work seems to be experimental/research
oriented.
Is there any implementation of reliable multicast on Linux that people
have used to solve real world issues?

Any help appreciated.

thanks
parag

If you want to have multicasting 100% reliable, you have to combine it with
some (eg TCP/IP) retransmission mechanism.
Only missed packets (use sequence numbers in the packets) need to be
retransmitted.

Johan

"parag" <(E-Mail Removed)> schreef in bericht
news:(E-Mail Removed) om...
> Hi,
>
> I want to look at the possibility of using reliable multicast to send
> software updates and periodic config/status information to all hosts
> on an Ethernet network.
>
> Most of the reliable multicast work seems to be experimental/research
> oriented.
> Is there any implementation of reliable multicast on Linux that people
> have used to solve real world issues?
>
> Any help appreciated.
>
> thanks
> parag

Johan Hendriks wrote:

> If you want to have multicasting 100% reliable, you have to combine it
> with some (eg TCP/IP) retransmission mechanism.
> Only missed packets (use sequence numbers in the packets) need to be
> retransmitted.
>

That would be difficult to achive. For example, with tcp, there is one
connection, between two hosts. Trying to maintain error detection &
retransmission with multiple hosts isn't supported.

--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.

(E-Mail Removed) (parag) wrote in message news:<(E-Mail Removed). com>...
> Hi,
>
> I want to look at the possibility of using reliable multicast to send
> software updates and periodic config/status information to all hosts
> on an Ethernet network.

What sort of config/staus info are we talking about and why would
multicasting be the best way to "distribute" it -- multicasting is a
"subsciber" initiated request, you can't "push" data to the
uninterested.

> Most of the reliable multicast work seems to be experimental/research
> oriented.
> Is there any implementation of reliable multicast on Linux that people
> have used to solve real world issues?
>
> Any help appreciated.
>
> thanks
> parag

Since you are looking to "broadcast" to _all_ hosts why use a "host
subscriber" model?

Many multicast services are available on Linux -- it's been several
years since I've played with them. Could you find a working demo
"model" similar to your needs to help you out?

I suspect that what you are after may be the work with multicasting
and IPv6 which offers an "all hosts" multicast addressing scheme. I'm
not too familiar with it however, and you can probably Google for hits
pertinent to your project better than I can.

Be warned that getting any kind of multicasting working on a LAN is
not as easy as it sounds -- there are a number of protocols that have
to be correctly set up and running. Give yourself time to play with
it and get familiar with its quirks.

You may want to consider another approach depending on your needs.
Are you sure there are not already implementations similar to what you
need that use unicasting and TCP?

not much help, I'm afraid,
prg
email above disabled

parag <(E-Mail Removed)> wrote:
> Hi,
>
> I want to look at the possibility of using reliable multicast to send
> software updates and periodic config/status information to all hosts
> on an Ethernet network.

You're kind of assuming that the hosts will never be different (though
you don't say what you mean by "updates", that could take various forms.

There is no reall standard solution wrt reliable multicast on Linux.
Scalable Reliable Multicast (SRM) would be the protocol you would want,
though I don't know what support for it is like.

apt-cache search multicast
emcast - multicast toolkit
flamethrower - Multicast file distribution utility
netcast - tool for synchronized multicast data transmission
systemimager-server-flamethrowerd - SystemImager boot binaries for i386
client nodes
udpcast - multicast file transfer tool

You'll notice that there is an entry here for System Imager, which
supports multicast updates now (though I've not used that new feature).

Package: systemimager-server-flamethrowerd
Description: SystemImager boot binaries for i386 client nodes
SystemImager is a set of utilities for installing GNU/Linux images to
client machines over the network. Images are stored in flat
files on the server, making updates easy. rsync is used for transfers,
making updates efficient.

(E-Mail Removed) (parag) wrote in message news:<(E-Mail Removed). com>...
> Hi,
>
> I want to look at the possibility of using reliable multicast to send
> software updates and periodic config/status information to all hosts
> on an Ethernet network.
>
>
FYI,

Tactix has a commercial copy utility call MRCP. MRCP is a file copy
utility that can reliably Multicast or Broadcast files to remote
systems. More infomation can be found at:

http://www.tactix.com/prodserv/software/mrcp.php

Jim