This workpackage is being done by SICS, Cambridge University and Glasgow University. It comprises the following tasks:
(SICS, Cambridge and Glasgow)
IPv6, the next generation Internet protocol, is being defined to provide a larger address space, but also includes syntax to support a new concept called flows across an Internet. The quality of service of a flow can be supported through reservations, queueing mechanisms, etc., in routers and hosts. IPv6 will enable Nemesis to offer distributed multimedia services across the Internet.
To enable Nemesis to communicate with Internet-based multimedia applications Nemesis requires a runtime environment which enables applications to use datagram-based protocols such as IP. Currently the xkernel is used to provide IPv4 support, however a proper framework for the use of connectionless protocols is required. This task will design a set of shared libraries for the support of datagram-based protocols on Nemesis. The libraries will provide packet-filtering functions for de-multiplexing received packets to the appropriate application, based on the protocol and receiver address, provide management of packet transmission over the network, and contain a framework for implementing the connectionless protocol stack itself as a shared library used by the application. The design will provide a framework rich enough to support any datagram-based protocol.
version is also available.
(SICS, Glasgow and Cambridge)
Once the preliminary design of the environment is complete, the project will commence with its implementation. The continued refinement of design and implementation will take place concurrently. The connectionless protocol environment will then be used as the framework for an implementation of IPv6 on Nemesis. Initially this implementation will be based on the Ethernet, and will allow Nemesis to communicate with Unix workstations (at SICS) which incorporate IPv6 functionality. The research output of this work will be considerable -- it is highly desirable to move away from kernel-based implementations of communication protocols, and this work will provide insight into the implementation of IPv6 in user space.
The principal advantage of IPv6 over IPv4 is the notion of a flow to which QoS specifications can be attached. The flow identifier in IPv6 can be mapped directly into an ATM virtual circuit/path identifier, thus minimising protocol overhead when layering IP over ATM. Thus flows in the Internet can be mapped to virtual circuits in the ATM network and quality of service for real time multimedia applications can be preserved end-to-end. In addition, IP and ATM define very different notions of multicast. Unification of multicast in IP and ATM is necessary to provide quality of service to the user. These activities can lead to standardisation in both Internet and ATM communities.
The Resource reSerVation Protocol (RSVP) is currently being defined in the Internet standardisation groups to provide resource reservation primarily for multicast transmission of digital audio and video. The distinguishing features of RSVP are that reservations are initiated by the receiver and reservation state is "soft" meaning that resources can be reclaimed easily by routers as routes change, but that state must be refreshed by messages from senders and receivers. These mechanisms are contrasted with ATM signalling which uses hard state and sender based reservations. This contrast presents a challenge in providing Internet resource reservation on the project's ATM network.
(SICS, Glasgow and Cambridge)
Taking the above results, the Nemesis IPv6 implementation will be mapped onto the ATM functionality provided by Nemesis. This will enable applications on Nemesis to use IPv6 over the ATM network.
The IETF has not yet defined any RFCs for the mapping of IPv6 onto ATM. We anticipate that the output of this task will feed directly into the IETF standardisation process, contributing to the development of RFCs for IPv6 on ATM. This task will also track the relevant IETF work during the course of the project.
A source licence for ATM signalling and control software has been acquired by the project from Nemesys Research Limited. The terms of this license cover the distribution of three packages used in ATM signalling, namely SSCOP, Q.2931 and ILMI. The license agreement grants access to the source to Cambridge only, and permits the distribution of the packages in binary form for use on Nemesis, by members of the project only. The packages will first need to be ported to Nemesis from the Unix platform on which they currently run. This work will be carried out by the University of Cambridge. Subsequent to this work, the derived software (in binary form) will be available as part of any distributed version of Nemesis under the binary licence agreement with Nemesys Research Limited. The binary packages to be made available will be suitable for use on Nemesis only. The licence permits project partners to re-distribute the binary packages for use in research based on Nemesis only.