Subject: Multicast for dialup customers?

From: Richard Williams <[email-masked]>
Date: Thu, 22 May 1997 11:24:38 -0700 (PDT)

Does anyone know of any working models or tests for providing multicast to
dialup customers? Specifically Win95 dialup. What are some of the more
obvious problems? What equipment is being used? Most importantly why not?
ANY information is greatly appreciated!

rw

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From: Petri Helenius <[email-masked]>
Date: Thu, 22 May 1997 23:22:29 +0300 (EEST)

> ANY information is greatly appreciated!
We've been running this with NBMA-mode PIM with AS5200 and it works.
Does not obviously provide you with high-quality video feeds though :-)

Pete

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From: Steve Deering <[email-masked]>
Date: Thu, 22 May 1997 14:46:46 -0700

> ANY information is greatly appreciated!

This reminds me of another question I have.  During the multicast tutorial
that I co-taught at Interop a couple weeks ago, the usual question came
up of how someone with a dialup PC at home can connect to the MBone, in
the case where the dialup access router does not itself support IP multicast
forwarding and IGMP across the dialup link.  I gave the two answers I was
aware of:

	(1) Run some flavor of BSD on the PC, plus mrouted, and establish
	    a DVMRP tunnel from the PC to an MBone router somewhere in
	    the Internet.  This doesn't satisfy those who want to run
	    Windows or NT on the PC.  (As far as I know, neither Windows
	    nor NT currently support any flavor of mrouted.)

	(2) Take a second PC and place it between the dialup line and the
	    original PC, e.g., like this:

		PC1 ---<ethernet>--- PC2 ---<dialup>--- AccessRouter

	    Then run Windows or NT on PC1 and run BSD and mrouted on PC2,
	    with a DVMRP tunnel from PC2 to an MBone router somewhere
	    in the Internet, and IGMP and native IP multicast being spoken
	    between PC1 and PC2.

Then someone in the class suggested another mechanism that might work.
Supposedly, Microsoft is pushing a protocol for tunneling PPP over IP
(called LTTP -- layer two tunneling protocol -- or something like that;
with great effort, I will suppress my architect's jerking knee).  I believe
this development is being pursued in the IETF, so other vendors may also
have bought into this LTTP.  So, if all the following statements are true:

	(1) LTTP support is built into Windows and/or NT.

	(2) Windows and/or NT can perform the host part of IGMP over an
	    LTTP tunnel (which it naturally ought to do, but one must not
	    make any assumptions...).

	(3) LTTP is supported by some vendor's multicast-capable router.

	(4) The LTTP-supporting router can perform the router part of IGMP
	    over an LTTP tunnel (which it naturally ought to do, but...).

THEN, it ought to be possible to connect a lone dialup PC into the MBone
via an LTTP tunnel.  So, my question is: are the all of the above statements
true?  If someone can confirm that the first two statements are true, I can
check the veracity of the last two statements for at least one router vendor.
:-)

(If this works, I hope it won't be used as an excuse not to upgrade the
dialup access routers to support native IP multicast.  Tunnels, whether
of the DVMRP flavor or the LTTP flavor, have significant performance and
management costs which are best avoided whenever possible)

Steve

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From: "Lutz Grueneberg, RVS" <[email-masked]>
Date: Thu, 22 May 1997 23:59:04 +0200 (MET DST)

Hi Richard,

> ANY information is greatly appreciated!
If you mean the scenario that a win95-user is connected via ISDN or
V.34 with syncPPP or PPP to a terminal server like a Ascend Max I can
tell you that I currently work on that. It is a software-only
solution with mixers and transmitters and the current prototype works well
on my systems at home and at the university but there is still some work
to do in the part of the RTP mixer. 

For the moment "Mash" from Jon Crowcroft might be an adhoc 
solution for your problem. See 

http://www.cs.ucl.ac.uk/staff/jon/

or 

http://nic.merit.edu/~mbone/index/titles.html#monstermash

Cheers,
 Lutz
--
// Lutz Grüneberg                Lehrgebiet Rechnernetze und Verteilte Systeme
//                               Universität Hannover
//                               Schloßwender Str. 5
// [email-masked]     D-30159 Hannover, Germany
// Public PGP-Key available: http://www.rvs.uni-hannover.de/people/gruen.html
//                           http://bs.mit.edu:8001/pks-toplev.html

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From: Amancio Hasty <[email-masked]>
Date: Thu, 22 May 1997 19:37:47 -0700

Hi,

Another solution is to run a router at home which supports IP multicast
something like Whistle's Interjet which basically is a FreeBSD box and
provides mail, web server , ftp, firewall, mrouted, etc...

	Regards,
	Amancio

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From: Petri Helenius <[email-masked]>
Date: Fri, 23 May 1997 09:24:45 +0300 (EEST)

> provides mail, web server , ftp, firewall, mrouted, etc...
Yes, if the case is like many of us that the number of hosts at home
is greater than one. For the single-PC case IGMP over dialup works
just fine if the access server is up to it.

Pete

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From: Stephen Casner <[email-masked]>
Date: Thu, 22 May 1997 23:17:08 -0700 (PDT)

Steve,

> management costs which are best avoided whenever possible)

I have another concern with tunneling PPP over IP: it may preclude the
use of IP/UDP/RTP header compression over the modem link because the
higher loss rate and longer delay of the tunnel compared to the single
modem link would render the compression ineffective.  In many cases,
the desire for multicast access over dialup is to allow exactly those
applications that would benefit from this header compression.

							-- Steve

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From: Amancio Hasty <[email-masked]>
Date: Fri, 23 May 1997 00:10:28 -0700

Hmm...

Is there a WinXX ppp implementation which supports ip multicast if so
then the problem is reduce to the ISP's router to support ip multicast
over the PPP link. Sounds like a good criteria for chosing a tcp/ip stack
and ISP 8)

	Cheers,
	Amancio

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From: Petri Helenius <[email-masked]>
Date: Fri, 23 May 1997 10:43:28 +0300 (EEST)

> over the PPP link. Sounds like a good criteria for chosing a tcp/ip stack
The IP stack that comes bundled with win95 supports IP multicast over
PPP as it supports IP multicast over other media.

I would guess NT4.0 uses the same stack. (but haven't tried this one)

Pete

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From: Jin YANG <[email-masked]>
Date: Fri, 23 May 1997 10:46:10 +0100

> ANY information is greatly appreciated!

we here at UCL developed a software solution which allows win95 users to join
mbone sessions via ISDN (the win95 stations connect to a Ascend ISDN gateway).
It tried to address two problems: Mbone connectivity and mismatch of the 
bandwidth  required by normal Mbone sessions and the bandwidth available over 
ISDN. It consists of a audio mixer/transcoder (rat3.0.18 from UCL can act as a 
mixer also performing transcoding), a video filter (adapted from the video 
gateway engine developed by Amir et al., http://http.cs.berkeley.edu/~elan/), 
and a user interface allowing remote mornitoring/control. More details can be 
found at: http://www.cs.ucl.ac.uk/staff/J.Yang/doc/report2.ps.Z.

regards,

Jin

================================
Jin Yang
Computer Science Department,
UCL, London, UK.
email: [email-masked]

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From: Peter Parnes <[email-masked]>
Date: Fri, 23 May 1997 12:15:47 +0200

And I at CDT have developed something called mTunnel which is a mcast tunneler that works under windows. It is a general tunneler where the user explicitly selects which sessions to tunnel. mTunnel has a built in session directory for easier tunneling and a built in HTTPd for easier installation as the interface is through the WWW.

The program and a paper describing it can be found at
<URL:http://www.cdt.luth.se/~peppar/progs/mTunnel/>

/P

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From: Yves Lepage <[email-masked]>
Date: Fri, 23 May 97 07:43:02 -0400

Hi all,

I just got this:

CISCO AND MICROSOFT DEMONSTRATE TUNNELING PROTOCOL INTEROPERABILITY
Cisco Systems and Microsoft last week demonstrated
interoperability of their layer 2 tunneling protocol (L2TP)
implementations.  The IETF's emerging L2TP standard is being
developed for building virtual private networks (VPNs) over the
Internet or other public networks. Cisco plans to have L2TP
available in version 11.3 of its IOS software, while Microsoft
plans to include L2TP in version 5.0 of Windows NT Server. L2TP is
expected to reach RFC status later this year.  The most recent
draft of the L2TP specification is available online.
(http://ds.internic.net/internet-drafts/draft-ietf-pppext-l2tp-
03.txt)
Company News Releases, May 21, 1997

Yves Lepage

Begin forwarded message:

X-SMTP-Posting-Origin: tweetie.canarie.ca ([email-masked] [199.212.24.2])
To: Steve Deering <[email-masked]>
Cc: [email-masked], [email-masked]
Subject: Re: Multicast for dialup customers?
Date: Fri, 23 May 1997 13:59:41 +1000
From: Brian Keck <[email-masked]>
Sender: [email-masked]

>(called LTTP -- layer two tunneling protocol -- or something like that;

Could this be PPTP (point to point tunnelling protocol)?  A few pointers ...

	http://www.ascend.com/techdocs/pptpfaq.html
	http://www.3com.com/0files/releases/mar0496b.html
	http://www.nts.com/NTS/
	http://www.microsoft.com./windows95/info/pptp4w95.htm

Brian Keck

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From: Michael Benson <[email-masked]>
Date: Fri, 23 May 1997 10:29:00 -0400 (EDT)

I believe NT 4.0 is using Winsock version 2.0

Michael

-- 
Michael Benson
WWW:    http://bacon.gmu.edu/~mbenson
Email:  [email-masked]          Whois: whois -h gmu.edu mbenson