SHENKER: FUNDAMENTAL DESIGN ISSUES FOR THE FUTURE INTERNET increase in price is compensated by the increase in the quality reservations for real-time applications, then usage pricing could be centered on the high quality real-time services most users of the Internet do not have to worry and not applied, at least in the near term, to the lower about their usage of the network incurring additional costs quality services. Moreover, much of the authentication and (although users connected to the Internet through a public accounting infrastructure for this charging could be added access provider sometimes do have usage-based charging). The along with the reservation mechanism, and so the best-effort introduction of pricing, especially usage-based pricing, into the architecture could be left relatively intact. This would leave met will involve major changes in both design and culture. undisturbed the cultural aspects of the current best-effort While most popular user interfaces hide the details of network Internet while charging a premium for high quality video and activity, once charging is in place the user interface will audio connection probably need to reveal the costs to the user. Also, the basic Clearly, these incentive issues are extremely important and network architecture must incorporate sufficient capabilities many issues remain unresolved. See [4], [8]. [30], [37] for to do the requisite authentication, accounting, and billing. further discussion of pricing and incentive issues Perhaps most importantly, such charging could alter the"gi economy"and browsing mentality that exists in the Internet day, The Internet is such an exciting development largely C. stability ecause of the cornucopia of information and resources freely available; unfortunately, once there are charges for network The other implication of the explicit approach is that the usage users will be less likely to disseminate information network service offerings must be known to applications. 20 widely. Moreover, many users spend hours browsing through Applications must know the set of services in order to ask for the Internet, much as one browses through a bookstore: if the service, and they must know the characterization of the delivered service-if any-in order to decide which servic take books off of a shelf in a bookstore, such browsing would best meets their needs. Since knowledge of the service model be seriously curtailed Thus it appears that neither the user must be embedded in applications, the service model must interfaces nor the basic architecture are ready to support such remain stable. though extensible. That is, it can be extended pricing, and it is also not clear that the current Intemet culture further but the services that are already in place cannot be could survive its introduction easily altered because this would interfere with the installed Do these dire consequences mean that we should not extend application base the service model? This is certainly a debatable point, and one The service model serves as th n of network that should be debated more extensively than it has. It should service that applications can be programmed against.Because be noted that while extending the service model raises the of this, it is the most fundamental, and most stable, aspect of issues of incentives when deciding how to send data. even the network architecture. The underlying network technologies in the case of a single class of best-effort service we nee can change, and even IP can change, without disturbing address the incentives of whether to send data. Currently, of the service model is both an advantage and a disadvantage ine, but rough adherence to rules of etiquette, along with It is an advantage because the service model then provides equate provisioning, have kept the Internet in relatively good a useful abstraction of network service. It is a disadvantage shape. However, once"junk mailing"becomes commonplace because if the initial service offerings are not well designed and automatic browsers(agents automatically browsing the it is much more painful and disruptive to change them; in Internet and retrieving anything that looks interesting) the implicit approach, such incremental adjustments would be widely deployed, the Internet will suffer. Even in the absence In the explicit approach, the service model is not to discourage or at least prioritize use: MacKie-Mason and it is uniform. That is, there is single IP service Thus, while usage. opposed to the implicit case where each router co based pricing may have undesirable consequences, we nee different set of service offerings. This uniformity imposes a to confront its existence regardless of our decisions about standardization requirements on network routers and subnets extending the service model of ter and subnet standards. call them network We should also note that there are pricing mechanisms element requirements, must be developed so that any con which would have less of a negative impact, and tha catenation of routers and subnets obeying these standards ca re incentive schemes which do not rely primarily on pricing. support the end-to-end service offering advertised by IP.Note For instance, quotas could be applied to an institution at its hat the service model is a set of end-to-end services and it access point to the Internet, and then the issue of allocating is up to the network to ensure that the services delivered at becomes a local problem for that intitution which,in uld d through informal social conventions, Also, if the network offered 20 Since one could have his additional complication does not alter the points we are making