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We have looked at the evolution of the Internet from Best Effort, FIFO, Destination Routed, Unicast network, to a multi-service, QoS Routed, multicast capable system. We have seen that very detailed progress has been made in that if supported by the routers along an end-to-end data path, RSVP can permit end systems to request Integrated Services that provide end applications with enhanced QOS commitments over conventional best-effort delivery. RSVP can be used by end applications to select and invoke the appropriate class and QOS level. In addition if the OPWA reservation model is used with RSVP then the requesting application is able to determine the resultant end-to-end QOS in advance of making the reservation. Without RSVP, a fall back service of best effort is still available from the unused capacity. In the near future, some research needs to be carried out in a number of areas:
Accounting and Billing needs to be integrated into the model in a scaleable way.
Aggregation of non-specifically related reservations (or flows) would be useful - in the same way that ATM provides Virtual Paths as well as Virtual Circuits, we might like to build virtual private Internets using, for example, the address aggregation mechanism CIDR, to be used within a reservation (the extension has been proposed in the RSVP working group to allow the generalised port to be accompanied by masks, in the same way that routing protocols distribute updates with masks).
Authentication of users of RSVP is clearly essential if we are to incur bills when we use it.
The usage accounting model must accommodate mirror servers in some way.
Some scheme to permit settlements or something akin to them will need to be evolved to allow deployment of RSVP and Integrated services across paths that entail more than a single Intranet or commercial Internet Service Provider.
Lastly, simply experience of using a multiservice networks is needed to see which pieces of this complex system are really used frequently, since it is not at all clear that the entire edifice is all either necessary, or sufficient.

next up previous contents
Next: IP and ATM Up: Network Service Models Previous: QoS Routing