Making MBone tools to be widely used by non-experiencied people
An integration with e-mail and WWW
Pedro M. Ruiz Martinez
Centro de Comunicaciones CSIC/RedIRIS
c/Serrano, 142. 28006 Madrid (Spain)
Tlf: +34 915855150 Fax: +34 915855146
Although IP multicast is a very good solution for internetworking multimedia
in many-to-many communications, there are still few people using it seriously.
Usually this technology is only used by active participants in its deployment.
There are various issues making people to avoid using this technology.
However, all these issues are not technical. Non experienced people usually
find easier to use some other H.323 applications than the MBone tools like
vic, vat, sdr, and so on. In this paper we will describe a way to integrate
MBone tools with e-mail and WWW in order to make them easier to use. We
will also see how to use this technique for providing secure multicast
videoconferencing facilities and how to integrate it with a well-known application
for collaborative work.
IP multicast was first defined in the Steeve Deering thesis  at about the
same time as the WWW. However, its deployment has been very slow and there
are still some issues that need to be solved in order to become IP multicast
into a real Internet service.
This slow evolution can be explained in several ways: providers needed
continue using their old routers before using new multicast capable equipment,
multicast traffic was difficult to manage, and so on. It's like the dog
that bits its own tail. Network operators and commercial ISP's do not offer
IP multicast to their customers because there is no real demand of such
traffic neither by the user nor the applications. In the same way, software
developers do not use IP multicast because there are only a few multicast capable
networks and so this functionality could be misused. So, IP multicat deployment is being very slow.
Although MBone tools can be used for teleteaching and videoconferencing
environments when scalable many-to-many comunications are needed, teachers and
other non-technician people find MBone tools difficult to understand and
to use. These users are not interested in having to learn which application
to use on what moment anymore. For example, they do not want to learn what's administrative
scoping. They only want to be able to interact between them without worring
about the underlying technology.
So, MBone is usually used by technician people. The key idea here
is that if we find a simple mechanism for non-technicians to take part
on IP multicast many-to-many communications, then IP multicast will start
to be widely used and so IP multicast backbones will start to be widely
deployed. At this point people will demand some requirements to multicast
networks that will make all of us to think about solving some of the current
IP multicast issues like:
A very few work has been done on these issues. Only  and  have started
seriously to find out solutions for these issues.
Controlling who joins to a certain multicast group
Controlling who sends data to a multicast group
Authentication in multicast environments
Controlling the scope of the sent packets
and so on.
In order to achieve our goal, we need to provide a solution meeting
the following requirements:
Compatible with the current technology
It needs to abstract the user from the underlying technology
It must support all of the current media formats available
It must allow us to have private sessions
It must be based on the current IETF standards
It must be simple to use, install and configure by everybody
This document is organized as follows: section two will
our prototype works, then section three will explain how to extend the initial
prototype for supporting ciphered sessions and finally section five will
show how to integrate this prototype with some other collaborative applications.
MBoneLaunch: How does the system work
To cover all the requirements previously described we are developing some
tools. Our solution consist on various parts:
So, combining these elements properly, we can construct several videoconferencing
scenarios that will make MBone tools useful and usable to a lot of people
within the academic and research environment.
MBone tools. The current versions of the MBone tools are very stable nowadays.
So we will use whichever tool supporting multicast. Some of them could
be the well-known vic, vat, and so on.
Mime-type. We are also using the reserved mime-type 'application/x-sdp'
for the integration of session descriptions with web or mail. The format
for these descriptions will be compatible with the SDP (Session Description
Launcher. We have also developed a tool called 'MBoneLauncher'. This tool
is in charge to launch the proper tools with the proper parameters. To
get the parameters and the tools to launch, this tools parses SDP packets.
The key is to attach this application to the mime-type 'application/x-sdp'
Session publisher. In order to become MBone sessions easily accesible to
everybody, we have developed an application that periodically publishes
all active sessions into a web page. This page shows all the interesting
information about the session and allows people to easily join a session
by clicking on the proper HTTP link.
Session creator. This tool is a web-interface for creating multicast sessions
easily. This allows non-expert people to create sessions without needing
to know anything about TTLs or specific tools to use.
One example scenario is what we have called 'Web-based videoconferencing'.
In this scenario, the final user participates in multicast sessions only
by accessing to an HTML page, look at the sessions available (like a
TV guide) and select the session to join. Once the user has selected the
sessions, the proper tools will be launched in his computer and he will be able
to interact with other participants.
There are at least two kind of processes taking part: On the one hand,
there must be an HTTP server that offers both the HTML page containing
the sessions and their corresponding SDP packets. Of course the SDP packets
are served like a mime-type 'application/x-sdp'. On the other hand, the
final user needs at least two elements: one is the set of tools to launch and
the second is the tool for processing the SDP packet (that we have called
'Mbonelaunch') and launch the tools.
So, the final user only needs to install the 'MBoneLaunch' script in
its system and then configure the mime-type 'application/x-sdp'
to this script in their browsers. This is very straightforward. The other thing that he needs
it to install the MBone tools in its system. Nowadays it is also very straightforward
on Windows platforms because the UCL distributes an installation program.
For Linux users it is also very easy to install the application because
we are building easily installable packages (for example RPM)for these
An example of this scenario is available at http://www.rediris.es/mbone/sesiones/
This scenario is very similar to the previous one. While in the previous
scenario all the active sessions were accesed via the browser's interface,
now a session description (SDP packet) can travel within an e-mail message.
It is as simple as attaching all SDP packets to your mail using the mime-type
The configuration in the user's side is similar to that used in the
previous scenario. The only thing needed is to link the mime-type 'application/x-sdp'
to the 'MBoneLaunch' script in the user's e-mail reader.
This approach offer us lots of alternatives like e-mail invitation to
Extensions for supporting ciphered sessions
Some of the new multicast-enabled tools allow us to transmit or receive
ciphered flows of data. This new functionality is very useful
but usually it is not very simple to use, understand and manage. So, we
have also provided this functionality to our 'MBoneLaunch' tool in order
to offer a private videoconferencing service to those who want to have
private talks and do not know anything about criptography or multicast.
Thus, the first extension that we have made allows our SDP parser to
interpret the SDP fields being used for criphering the session. So, if
a ciphered session is passed to our system, the 'MBoneLaunch' tool will
extract the keys that will be used to encrypt the session from the SDP packet
and will pass them to the proper tool.
The problem here is that if the keys needed to participate in the session
are in the SDP packet, somebody understanding the SDP protocol could also
extract the keys and participate.
One possible solution is to encrypt SDP packets and make the 'MBoneLaunch'
tool to decrypt them before parsing.
Some other solutions are for example to restrict the access to the web
pages containing the SDP packets for those private sessions or even to
send encrypted mail-messages when inviting to private sessions.
As we will see in the 'future work' section we are woking on integrating
this work with the recently usable IRIS-PCA project. This project consists
on building a Public Key Infrastructure (PKI) rooted at the RedIRIS Certification
Authority (CA) for the Spanish National Research Network.
Integration with other collaborative tools
As we have previously said, it is also interesting for the Spanish Research
community to integrate these videoconferencig capabilities with some other
tools used for collaborative work. For example, he has integrated our
solution with the well-known BSCW collaborative tool.
Nowadays, we are using this tool for offering support to 'Virtual Communities'
within our Spanish research environment. This project is called IRIS-CVU
. This web-based tool allows various users to work together from different
locations. We have added MBone tools to the list of tools available in
BSCW meetings. So, when a user from BSCW invites some other users in his
workspace, he can select to use 'MBone tools' for having the meeting. This
selection makes the BSCW server to send an e-mail invitation to every user
with the proper SDP packet and also allow for participating in the event
from the BSCW web interface.
Conclusions and Future work
This work is making people in the Spanish research community to think in
MBone tools as an easy and good technology to be used in their distance
work. People used to think that multicast was an experimental technology,
but nowadays multicast networks can work very good in some environments.
If people start using this technology seriously, we think that a lot of
effort will be done in order to become IP multicast into a real Internet
service. So, the current issues with IP multicast will be solved
because the demand of people using IP multicast. We think that it will
happen the same as with IP unicast. That is, when people started to use
it for business matters all the problems with authentication, privacy and
so on started to be solved. We think that pay-per-view multicast services
like streaming, or teleteaching will be the killer applications making all
these issues to be solved.
However, there are also various technical problems in our solution that
we need to address:
Nowadays, the groups and ports asigned when creating a new multicast session
are selected in a random way. But, it is the only alternative until the
IETF won't standardize new proposed mechanisms as AAP, MALLOC, or something
We have to improve our mechanism for solving the previously commented problem
with ciphered announces.
Nowadays the session list is created from the SDR cache. We are evolving our current prototype of a Java SAP/SDP parser. So this parser will listen to SAP.MCAST.NET group and will maintain an updated on-line list of active sessions.
We are also working on integrating all this elements with the IRIS-PCA
project for offering a private multicast conferencing service to the Spanish
academic and research community.
We are also planning to extend our system for supporting also a public
and private streaming service integrated on the web.
We are adapting our solutions to the new proposals for private multicast videoconferencing. For example, the new changes that SAP (Session Announcement Protocol ) is suffering.
 IGMP Extensions for IP multicast senders and receivers authentication.
N. Ishikawa, N. Yamanouchi and O. Takahashi. Internet Draft.August 1998
 Access control in multicast environments: an approach to senders
authentication. Antonio F. Gomez Skarmeta, Angel L. Mateo Martinez and
Pedro M. Ruiz Martinez. Proceedings of the IEEE LANOMS'99 pp 1-8, 1999.
 SDP: Session Description Protocol. M. Handley and V. Jacobson. RFC
2543. March 1999
 IRIS-PCA project. http://www.rediris.es/cert/iris-pca
 IRIS-CVU project. http://www.rediris.es/cvu/
 Multicast routing in a datagram internetwork. Steeve Deering. Ph. D. dissertation, 1991
 SAP: Session Announcement Protocol. M. Handley. Internet Draft. February 2000.Can be obtained from:http://www.ietf.org/internet-drafts/draft-ietf-mmusic-sap-v2-05.txt