High Performance Transports: HTPNET,TCP/IP, XTP, TP++ and RTPBy Zahid Hossain [email protected] high transmission speed of optical networks has resulted in shifting of communication bottlenecksfrom the transmission media to the host processing system, especially the transport protocol processing atthe end systems. New protocols, such as XTP, HTPNET, RTP, have been proposed by researchers tomeet the requirements of high speed networks. TCP/IP, which has been very successful as a transportprotocol for the last twenty years, is also adapting itself in high-speed network.Table of Contents:❍ Introduction❍ A High Performance Transport Protocol (HTPNET)HTPNET OverviewDesign issues on error control Mechanism for High speed networks (HTPNET)State Synchronization and Error RecoverySelective retransmissionCongestion AvoidanceArchitecture of HTPNETPerformance of HTPNET❍ High Performance TCP/IP (On Gigabit Networks)Performance on Local Area NetworksTCP common path optimizationsTCP Header predictionOther pre-packet optimizationPre-byte optimizationsPerformance of TCP on the InternetCongestion ControlTCP on Long fast NetworksHigh Performance Transports: HTPNET, TCP/IP, XTP, TP++ and RTPhttp://www.cis.ohio-state.edu/~jain/cis788-95/transport/index.html (1 of 18) [2/7/2000 11:15:46 AM]❍ XTP: Xpress Transport ProtocolXTP FeaturesSeparation of paradigm and policySeparation of rate and flow controlExplicit multicast supportData delivery service independenceOther features of XTPXTP Protocol ConceptsThe State MachineCommon HeadersControl Algorithms❍ TP++: A research project on Design issues of high-performance and multimedia protocols❍ Rapid Transport Protocol (RTP)❍ Conclusion❍ References1 IntroductionComputer networking technology has seen enormous growth over the past thirty years. In the1960's "networking" was synonymous with the telephone network, and communication speed ofhundreds of bits per second was common when using telephone modems; packet radio technologyincreased the data communications speed to thousands of bits per second. A new concept wasintroduced in 1970s: the Local Area Network(LAN). In particular, Ethernet brought transmissionspeed of 10 million bits per second (Mb/s). Again, in the 1980s, MAN (Metropolitan AreaNetwork) and LAN speeds increased to the order of 100 million bits per second, and now we arehaving WAN (Wide Area Network) with gigabit per second (Gb/s) networks using fiber optics.The high transmission speed of optical networks has resulted in shifting of communicationbottlenecks from the transmission media to the host processing system. TCP transport protocol hasbeen very successful for last twenty years, but the rapid advancement of fiber optics technologyand the demand for multimedia network services have accelerated the development of nextgeneration of lightwave networks. This lightwave networks are able to operate at a far greaterbandwidth in the multi-mega bits range, while offering low error rate performance. Such operatingspeed, however, has not been matched by a corresponding increased in transport protocolprocessing at the end systems. As the computer networking is changing, new protocols are beingproposed to meet the requirements of these fast networks. HTPNET(High-speed Transpot Protocolfor Net Works), XTP(Xpress Transport Protocol), RTP(Rapid Transport Protocol) and TP++ havebeen proposed to meet the requirements of future networks. TCP/IP has also been modified toHigh Performance Transports: HTPNET, TCP/IP, XTP, TP++ and RTPhttp://www.cis.ohio-state.edu/~jain/cis788-95/transport/index.html (2 of 18) [2/7/2000 11:15:46 AM]meet the requirements of future networks. In this paper I have discussed High PerformanceTransport protocols, their performances, and their future.2 A High Performance Transport Protocol(HTPNET)HTPNET or High-performance Transport Protocol system is designed to overcome protocolprocessing bottleneck. It is designed based on a highly parallel architecture and is designed toexploit the evolving characteristics of high speed networks. HTPNET uses an out-of-bandsignaling system based upon transmitter-paced periodic exchanges of state information betweenend systems. This mechanism exhibits several attractive properties which have been demonstratedto perform efficiently in a simulated high-speed environment with high bandwidth delay product.A formal validation on the mechanism has been performed using the SPIN [4] validation tool. Theanalysis has resulted in the uncovering of several properties of the protocol that have beenoverlooked during the initial design phase. An experimental implementation of HTPNET has beenconstructed from a network of T800 transputers. The results demonstrated the advantages ofexploiting a parallel architecture for protocol processing. The results obtained from the experimentprompted further exploitation of the parallel architecture of HTPNET to provide a suitableplatform for the parallel implementation of Presentation processing, which can incur highcomputation overheads. The protocol processing system is designed to be implemented on theT9000 transputer and C104 router technology. A simulation of the architecture has demonstratedthe feasibility of applying functional and packet parallelisms to protocol processing to match theever increasing processing demand of future high-speed networks. In this section we will discussdifferent aspects of HTPNET.HTPNET (High-speed Transport Protocol for Networks) is based on a highly parallel architecture.It also take into consideration the communication network characteristics, namely the connectionoriented nature of broadband networks, increased bandwidth-delay-product and lower error rates.HTPNET is currently implemented on a network of a T800 transputers. Experiments have revealedpromising packets transfer rate of 12,000 to 13,000 packets/sec with a packet size of 2 Kilobytes.As a result, a data transfer rate of more than 200 Mb/s could be achieved [5].2.1 HTPNET OverviewThe HTPNET aims to decuple as far as possible protocol processing from the main operatingsystem using an additional multiprocessor-based subsystem. In addition, the structure of theHTPNET protocol is based on several finite state machines which are designed to exploit a parallelimplementation and achieve high throughput.High Performance Transports: HTPNET, TCP/IP, XTP, TP++ and RTPhttp://www.cis.ohio-state.edu/~jain/cis788-95/transport/index.html (3 of 18)