BellCore Networking Discussion October 28, 1986 Topics in Networking · Sources of increased traffic (local, long-haul) · Directions in communications protocols · Problems of scale in large internetworks · Voice in local area packet-switched networks Sources of Increased Traffic (Local) · 13 Year phenomenon Laser printing High-performance workstations Packet-switched wide-area distributed communications? · Home (small business/institution) computing Chicken and egg -- substantial market at acceptable rates, none at today's New applications areas Diskless workstations Remote window systems (e.g., Sun's NEWS) Remote publication-quality filing and printing Bandwidth requirements (Response-time, not throughput) 9600 bps marginal 56 kbps tolerable ISDN, packet, Cable? CSDC (near-miss, so far) Ideal: packet-switched service at T1 data rates · Support of remote connections without bypass Fiber plant enhances desirability Switched service Sources of Increased Traffic (Remote) · 56K backbone now in Xerox · Very large latent market Critical mass (10,000 terminals in Xerox network) Function of cost and performance · Video conferencing beginning to take off · Portland experiment Will this sort of thing catch on? How soon? · Next increment: image transmission within integrated publication/telecopier/office systems Protocols · Interoperability a major issue X.400 (electronic mai) SNA TCP/IP (DARPA protocols) ISO (when?) ISDN? (not a complete architecture) · ISO 7-layer model versus simpler models: Link and transport layers intact Service layer: Remote procedure call (RPC) abstraction; lightweight (client-invisible) session layer Bulk data transfer, controlled by RPC Higher layers more properly treated as distributed applications, largely independent of communications · New DARPA/NSF high-performance protocol initiatives Problems of Scale · Can't control load through denial of service in a datagram-oriented network · Naming and resource management require distributed databases · Update and query problems in distributed databases unsolved, in general User-perceived performance problems Algorithms that scale catastrophically · Relative immaturity of network measurement/management tools · Recent case study within Xerox internet Distributed name database designed for 30 networks, servers network contains 300 networks, servers n3 update algorithms recently detected, replaced · Other exciting opportunities for research based on large, real, malleable internetwork Congestion control, flexible routing, . . . Voice in Local Area Packet-Switched Networks · Technically feasible Primary obstacle is packet delay CSMA/CD (Ethernet) issues not the major ones Requires proper internetwork engineering 50-phone prototype system in daily use at PARC BellCore work has reached similar conclusions · Technically desirable Integration of voice/data transmission Integration of voice recording, synthesis, recognition services Enhanced control, broadcast services, etc. · Economics not yet clear · Primary challenges are systems challences Continued reliability of base telephone features Workstation control of voice facilities Need for overall voice systems architecture Κ–"slides" style– PressFonts˜Iunleaded•Mark insideFooteršΡdis˜K– outsideFooterš˜title˜IraggedšΟbœž˜1Mšžœ&˜(Mšžœ(˜*Mšžœ,˜.M˜—˜$šž˜M˜M˜M˜5—šž-˜-M˜J˜M˜M˜(M˜.—˜M˜M˜˜M˜M˜—M˜/——šž.˜.M˜!M˜—M˜—˜%Mšž˜šž˜M˜1M˜ —Mšž*˜*šž˜M˜!M˜ —Mšž\˜\—˜ šž ˜ M˜M˜M˜M˜ M˜#—šž*˜*M˜ ˜M˜UM˜%—M˜f—Mšž5˜5—˜MšžM˜MMšž>˜>šžI˜IM˜#M˜&—Mšž=˜=šž)˜)M˜;M˜'MšœΟuœ.˜0—šžX˜XM˜+——˜,šž˜M˜ M˜,M˜(M˜.M˜-—šž˜M˜&M˜?M˜*—Mšž˜šž+˜+M˜0M˜'M˜+———…— t}