SiMPLE - the interactive multicast proxy

SiMPLE is an interactive IP-multicast solu-tion exploiting proxy/cache techniques. Thegoal is an efficient utilisation of broadbandnetworks providing broadcast transmis-sion. SiMPLE is a software system providingproxy functions at the server side and alsoat the client side. The SiMPLE client proxy (UES) accepts HTTPrequests, translates them into messageswhich represent UDP/ICP messages andchecks if it can satisfy this request from thelocally cached contents. If this is not thecase it forwards them to the SiMPLE serverproxy (BUS), which in turn translates therequest back into a standard HTTP formatwhich is then satisfied ba an external proxy.The reply to the original request is sentback via IP-multicast not only to therequesting client proxy but to the wholemulticast group. The motivation is thatother client proxies, which have notrequested this object, can store the resultson the local harddisk cache for laterretrieval or additional processing. Hence,SiMPLE provides both interactive cache rep-lication services and non-interactive multi-ple cache updates and uses satellitebandwidth in a very efficient mode.SiMPLE is an interactive multicast proxy,which replicates only that portion of theWeb, which has been requested by at leastone client. This approach allows broadbandoperators to determine dynamically thecontents which should be pushed when,since this can be deduced from their cus-tomers´ browsing behaviour. Hence, theyare able to utilise their bandwidth very eco-nomically.SiMPLE includes a powerful push servicewhich is supported by the DataCast proto-cols. In addition, it allows for cachingupdates during the off-hours, thus elimi-nating peak-hour bottlenecks. Cached con-tent, uniquely addressed by a URL, isavailable directly from the SiMPLE clientproxy through the users Web browser. Ulti-mately, SiMPLE also supports pushing ofvirtual domains, that is, domains which donot exist on the real Internet, making multi-media kiosks easy to implement and toupdate.SiMPLE enhances multicast enabled broad-band networks by seamless adding multi-cast proxy update services. Whereas current

gcs GmbH and Institute of Computer Science, Salzburg, Aus

hierarchical proxies are based on point-to-point cache updates, SiMPLE is truly apoint-to-multipoint solution. Integratingsophisticated multicast transport andsession protocols into a versatile multi-cast proxy/cache solution, SiMPLE signifi-cantly increases network efficiency.SiMPLE is an efficient overlay networksolution, bypassing highly loaded or con-gested links by multicast delivery. Broad-cast networks, such as wireless orsatellite, benefit immediately by multi-cast delivery. For isolated or poorly con-nected high-speed network islandsSiMPLE provides a means to speed upWeb downloads significantly.SiMPLE is perfect for highly asymmetricsatellite networks since it is specificallydesigned to use UDP over the returnchannel with limited capacity and IP-multicast on the forward channel. Bydesign SiMPLE uses TCP only at the edgesof the satellite network to connect clientsand client proxy, and server proxy andservers. Thus, SiMPLE performance is notaffected by TCP slow-start, window sizesand RTTs. On the contrary, SiMPLE is aninteractive multicast push service, whereperformance and quality of serviceparameters, such as rate and reliabilityare controlled by the SiMPLE proxies.SiMPLE is built around a flexible frame-work of functional modules and a controlprogram, managing required modules,such as the proxy and the cache, andoptional modules, such as the filter. Mostmodules can be incorporated or updatedon the fly. The SiMPLE configurationmanagement allows remote configura-tion and control of all modules through aWeb browser interface. Additionally,remote access and control can berestricted.SiMPLE is an Internet recorder, storingthe users most frequented Web contentson the users harddisk, thus eliminatingthe need to request and transmit it overand over again. In addition, it plays backthis content upon the users request,effectively eliminating the networklatency.SiMPLE supports the most popular oper-ating systems Windows (95/98/ NT/Me/2000) and Linux.

tria 22 March 2001

SiMPLE - the interactive multicast proxy

gcs GmbH and Institute of Computer Science, Salzburg, Austria 22 March 2001