Report on MBone Tools Selection

Introduction

MBone needs applications capable of multicast to carry out sessions on it.
The majority of these applications are for multimedia collaboration purpose 
and broadcast use.  Examples are video or audio broadcast, video tele
-conferencing, shared whitebroad and charting boards.  

For NPACI project, we are looking for MBone tools to do collaboration among 
parties in different sites.  Because of the different available connectivity, 
we recommend three layers of solutions.  First, for users with direct connectivity
to high speed backbone, we would would conduct experiments using high quality 
tools with MMX over ATM.  An ALX device over ATM be used for such users.  
For users, with general, low speed connections, like ISDN, we recommend using 
the ViewStation MP and ShowStation IP, both from Polycom Inc. 
(http://www.polycom.com).  The ViewStation can be used as the teleconference 
station for such users, and ShowStation IP can be used as text-based or 
image-based collabration for such users.  For users with reasonable quality 
teleconference and remote collabration needs and  usual high speed connectivity, 
we recommend a desktop solution using workstations equipped with MBone tools.  

This report summarizes the investigations on such MBone tools we have tested 
and talks about their capabilities and itegration issues.  This report 
addresses the issues for Milestone 1a.


Tools recommendations

During the investigation, we tried different tools for session diectory, for 
video conference, for audio conference, for shared white board, and 
for image sharing.

According to our tests, we would make the following recommendations:

For session directory, we recommend sdr. 
sdr from ISI is a session directory tool designed to allow the advertisement
and joining of multicast conferences on the Mbone.  It was originally
based on sd written by Van Jacobson at LBNL, but implements a later
version of the session description protocol than sd does.  sdr has so
called "plug-in" that can be used to invoke certain MBone applications
for certain type of sessions.  This makes adding and configuring new 
MBone tools easier.

For video tools, we recommend vic or optimized version nv.  
vic is from LBL.  It is an improved video conference tool inspired by nv.  
It is designed to be used in an IP Multicast network, while nv was designed
early without multicast in mind.  It uses standard RTPv2 protocol for real time 
data transmission, while nv uses its own protocol.  vic also supports a
variety of code formats and can use software or hardware decoding.  
vic currently doesnt have good support for some hardware video frame grabbers.
So, before such problem is resolved, we may need use nv for some platform,
like NetBSD.  Both of these tools are to supposed to be used in ordinary IP
network, so, they are both not so efficient to handle high volumn traffic.
Some optimization work were done on both of them.

For audio, we recommend rat; 
rat is a teleconference tool that allows users to participate in Internet.
rat is developed and maintaned at University College London.  It supports IP 
multicast and unicast.  It uses standard RTP and RTCP protocols for real time 
transmission, while other tools like vat uses its own transmission protocol.  
Current available rat supports five types of audio encoding. 

For shared white board, we recommend wb. 
wb is an Internet collabaration tool for text-based and diagram-based 
interactions.  It is from LBL.  It is designed to be used in an IP Multicast
network like MBone.  It is the only public domain available tool with such
capabilities.  However, it doesnt have source code making it hard to 
optimized and port.  Other similar tools are: nte for share and exchanges 
of text documents, imm for graphical data exchanges and share.

For image sharing, we recommend imm.
imm is from University of Hawaii.  It is designed to efficiently replicate 
files/file directories using a reliable dissemination protocol framework 
and provide archiving and post processing features.  

These tools are generally available on all unix-like platforms.  For Microsoft
Windows platforms, some tools may be not available.


Tool Capabilities

The MBone tools are capable of establish a multi-media session among many
parties.  To achieve better collabration, real-time quality of service is 
necessary.  RTP and RTCP are usually used.  Sessions can be found by session
directory tool using IGMP protocol communication to connected multicast router.


Tool Issues
o User Interfaces
MBone tools usually use Tcl/Tk to develop their user interfaces.  This make it
easy to port to different platforms.

o Control
The multicast sessions are managed by the session directory tools.  The 
session directory tools dectect ongoing sessions and disply them for users.
Once a user decides to participate in a session, it will lauch the approprite
tools according to the information about the ongoing session.  Also, session
directory tools can create new sessions according to the user, and advertises
the new sessions to multicast routers.  Also, session directory tool can schedule 
events automatically according to advertized schedules.

o Integration
Session directory tools and other collabration tools are usually integrated in a
loosely coupled fashion.  Session directory starts a specific collabration 
application by a command with approrite parameters of the session.


Conslusion

In summary, MBone tools use RTP and RTCP to transmit and receive data and 
meet the real-time requirements at the same time.  Sessions are mamanged 
by session directory tools using IGMP.  Session directory tools also are
responsible for activate specific audio or video tool for a specific session.
These tools usually uses Tcl/Tk-based user interface for portability concerns.