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 [6] 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 [1] and [2] have started seriously to find out solutions for these issues.

In order to achieve our goal, we need to provide a solution meeting the following requirements:

This document is organized as follows: section two will explain how 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:
  1. 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.
  2. 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 [3](Session Description Protocol) standard.
  3. 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'
  4. 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.
  5. 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.
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.

Web-based videoconferencing

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 users.

An example of this scenario is available at

Mail-based videoconferencing

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 'application/x-sdp'.

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 multicast sessions.

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.[4]

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 [5]. 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:


[1] IGMP Extensions for IP multicast senders and receivers authentication. N. Ishikawa, N. Yamanouchi and O. Takahashi. Internet Draft.August 1998

[2] 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.

[3] SDP: Session Description Protocol. M. Handley and V. Jacobson. RFC 2543. March 1999

[4] IRIS-PCA project.

[5] IRIS-CVU project.

[6] Multicast routing in a datagram internetwork. Steeve Deering. Ph. D. dissertation, 1991

[7] SAP: Session Announcement Protocol. M. Handley. Internet Draft. February 2000.Can be obtained from: