Subject: Doing ftp via multicast addresses.

From: [email-masked] (Kamal Dhaliwal)
Date: Thu, 15 Feb 1996 09:38:36 -0500

Does anybody has experience in doing ftp using multicast
addresses i.e.

If you want to ftp a file to 10 sites, can you use 
multicasting to send it to 10 different sites?

--kamal

---

From: Petri Helenius <[email-masked]>
Date: Thu, 15 Feb 1996 17:04:46 +0200

> multicasting to send it to 10 different sites?
You cannot use ordinary ftp-protocol to do point-to-multipoint transfers.
However there is an application (developed by StarBurst) that does
what you want. They call it MFTP.

Pete

---

From: Jon Crowcroft <[email-masked]>
Date: Thu, 15 Feb 1996 15:09:16 +0000

>multicasting to send it to 10 different sites?

no, no, no, no, no, no, no, no, no, no :-)

FTP uses TCP
TCP cannot use IP multicast - 

1/ the n-1 multiple SYN ACKs generated from
recipients of the SYN  after the first SYNACK  on connection setup cause 
it to reset

2/ the ACKs for outbound data packets will congest the link back to
the sender....(actually, for 10 receivers, this might not be so bad in
practice, but because of 1, you wont even get this far...)

i.e. positive acknowledgement is not a good idea for one-to-many
applications

see
http://hill.lut.ac.uk/DS-Archive/MTP.html
for a list of pointers to places that offer solutions....

probably the front runner right now is RMP, though for other
applications, Wb and Imm for example, a more application layered
approach is appropriate.....

but it would sure be neat to have a generic reliable s/w distribution
application....

see
http://www.inria.fr/rodeo/personnel/Christophe.Diot/biblio-xcast.html
(if its still there)
for more general group communication material

cheers
 jon

---

From: "Todd L. Montgomery" <[email-masked]>
Date: Thu, 15 Feb 1996 13:58:03 -0500 (EST)

RMP - the Reliable Multicast Protocol is well suited for this sort of 
thing. Take a look at:
	http://research.ivv.nasa.gov/projects/RMP/RMP.html

-- Todd Montgomery
[email-masked]

---

From: [email-masked] (Rajesh Talpade)
Date: Thu, 15 Feb 1996 14:16:35 -0500 (EST)

Hi

As a matter of fact, we have indeed developed a protocol for 
Reliable Multicasting using TCP/IP. We have also developed a 
user-level ftp-like application, xftp, which uses the reliable
multicast transport service offered by our stack.

You can look at 
http://www.cc.gatech.edu/computing/Telecomm/playground/SCE/outline.html
for more info.
The ack implosion issue is still unresolved at this point.

Regards,
Rajesh.

---

From: Greg Minshall <[email-masked]>
Date: Thu, 15 Feb 1996 14:00:23 -0800

There was an interesting paper in the last USENIX --- "Why Use a Fishing Line 
When You Have a Net?  An Adaptive Multicast Data Distribution Protocol" --- by 
J. R. Cooperstock <[email-masked]> and S. Kotsopoulos 
<[email-masked]> from the U. of Toronto.  They point people at 
http://www.ecf.toronto.edu/afdp to get the source code, etc.

---

From: Zheng Wang <[email-masked]>
Date: Fri, 16 Feb 1996 11:12:45 +0000

Kamal,

We have been playing with a toy we developed called mmd (multicast mail
distribution), which can also be used for distributing software
and files. For more info, anonymous ftp to cs.ucl.ac.uk and cd dir
to darpa/mmd.

Cheers
Zheng