Subject: MBone over Frame Relay

From: [email-masked] (Ridvan Erdogan)
Date: Sat, 14 Sep 96 02:01:51 PDT

Hi all,

About 5 or 6 months ago, we asked to ourselves whether we can implement
multicasting and MBone over Monterey BayNet which is a Frame Relay WAN that 
connects K-12 schools, educational institutions throughout the Monterey 
and Santa Cruz counties of central California.
 
Since Frame Relay is a connection-oriented protocol, the multicast services
as specified by Frame Relay PVC Multicast Service and Protocol Description, 
Implementation Agreement [Swallow, 1994. Available at http://frame-relay.indiana.edu/5000/Approved/FRF.7/FRF7-TOC.html]
rely on special servers. However, such servers were not available for our use.
Instead of using dedicated servers, we enabled IP multicast using Protocol 
Independent Multicast (PIM) protocol on already-installed Cisco 2500-series
Frame-Relay-capable routers. This provides us a multicast service which is
service provider and server independent. Now we are able to send live audio/video
over Monterey BayNet Frame Relay links.

In our thesis research, we have concluded that the MBone over low-speed (128 Kbps)
Frame Relay links is possible and the MBone software tools provide adequate 
performance for distance learning on even low-cost personal computers.

To safely integrate this regional Frame Relay MBone with the global MBone,
we permit our school's FR router (which is NOT the internet service
provider of Monterey BayNet) to pass only the IANA-specified
private experiment multicast address  224.0.1.20.

This permits our regional MBone to have the following connectivity:

 -------------------------------------------------------
| Scope          |     ttl        | Multicast Address   |
 -------------------------------------------------------
| Local Site     |    ttl < 8	  |   224.0.1.20        |
 -------------------------------------------------------
| Regional       |  16 < ttl < 32 |   224.0.1.20        |
 -------------------------------------------------------
| Global         |   ttl > 32     | any other than 	    |
|                |                |   224.0.1.20       	|
 -------------------------------------------------------

This combination of ttl control and administrative scoping effectively
integrates our regional MBone with the global MBone, especially for
border nodes (typically universities) that have their own ISP and
MBone links.  However, it does have one big loophole.  Naive users who 
multicast to 224.0.1.20 with ttl>32 can provoke multiple packets globally.  
We believe that addition of administrative scoping capabilities 
(selection/deselection of addresses) in encapsulated tunnels handled by 
mrouted might fix this problem.

Enabling multicasting requires monitoring multicast connectivity. The public
domain multicast monitoring tools such as mtrace and mrinfo are available 
only to UNIX-based platforms. However, most Monterey BayNet sites are K-12 schools 
that mostly have Windows and Macintosh platforms. To meet the monitoring needs of 
the Monterey BayNet sites we developed monitoring Web pages by using perl/CGI 
scripting. The Monterey BayNet sites now are able to run mrinfo and mtrace 
remotely by accessing these pages.

The following is the abstract of our thesis. This thesis research is on-line
and available at http://www.stl.nps.navy.mil/~iirg/erdogan/thesis.html
 
Any comments are very appreciated.

I am a graduate student at Naval Postgraduate School, Monterey, California and 
going to graduate on September 26, 1996. After graduation I will return to 
naval duties in my home country Turkey (Turkiye). I would like to thank my thesis
advisor Don Brutzman for his continuous support. I am grateful for the tremendous
help I have received from the list. I also would like to thank Bill Fenner, John
Hawkinson, Ajit Thyagarajan, Jon Crowcroft and many others for usefull information 
they have provided.

Regards Ridvan.
 
                                      ABSTRACT
 
 	The major problems addressed by this thesis research are how to
 implement multicast over the Monterey BayNet to enable live audio/video for
 distance learning, how to safely integrate regional Frame Relay multicast with
 the global MBone, and how to monitor multicast connectivity over the Monterey
 BayNet.
 
 	To implement multicast and MBone over the Monterey BayNet without
using dedicated multicast servers, we enabled Protocol Independent Multicast
(PIM) protocol on already-installed Frame-Relay-capable routers. By
implementing multicast over Monterey BayNet, we show  that the current MBone
software provides the same performance that it provides on regular Internet
connections even on low-speed (128Kbps) Frame Relay network connections and
low-cost personal computers. In order to control the scope of the regional
multicast and to safely integrate regional Frame Relay multicast with the
global MBone, we used administratively controlled multicast group address
(224.0.1.20) in addition to the use of time-to-live (TTL) control
mechnanism. This eliminates global duplication of multicast packet delivery.
 
    Public-domain multicast monitoring tools are used to monitor the
multicast connectivity through internetworks. Since these tools are available
only to UNIX-based platforms, they cannot be used by the regional sites that mostly
have Windows and Macintosh platforms. We developed Web-accessible multicast
monitoring pages in order to meet the multicast monitoring needs of the
regional sites. Participating  sites are now able to monitor regional
multicastconnectivity by accessing these pages, which permits remote problem
diagnosis. That was previously impossible. Finally we synopsize firewall requirements for
secure and effective use of multicast.
 
-- 
Ridvan Erdogan
[email-masked]
 
Some men see things as they are and say "WHY?".
I dream things that never were and say, "WHY NOT". 
Bernard Shaw