Contents vii 2.5 Framing,73 2.5.1 Character-Based Framing,75 2.5.2 Bit-Oriented Framing-Flags,76 2.5.3 Length Fields,79 2.5.4 Framing with Errors,80 2.5.5 Maximum Frame Size,82 2.6 Standard DLCs,85 2.7 Session Identification and Addressing,91 2.7.1 Session Identification in TYMNET,92 2.7.2 Session Identification in the Codex Networks,94 2.8 Error Recovery at the Network and Transport Layer,95 2.8.1 End-to-End acks,Flow Control,and Permits,96 2.8.2 Using End-to-End acks for Error Recovery,98 2.8.3 The X.25 Network Layer Standard,99 2.9 Summary,101 2.10 Notes,Sources,and Suggested Reading,102 PROBLEMS,103 Chapter 3 DELAY MODELS IN DATA NETWORKS 111 3.1 Introduction,111 3.1.1 Multiplexing of Traffic on a Communication Link,112 3.2 Queueing Models-Little's Theorem,114 3.3 The M/M/I Queueing System,122 3.3.1 Main Results,124 3.3.2 Occupancy Distribution Upon Arrival,132 3.3.3 Occupancy Distribution Upon Departure,134 3.4 The M/M/m,M/M/,and M/M/m/m Systems,134Contents vii 2.5 Framing, 73 2.5.1 Character-Based Framing, 75 2.5.2 Bit-Oriented Framing--Flags, 76 2.5.3 Length Fields, 79 2.5.4 Framing with Errors, 80 2.5.5 Maximum Frame Size, 82 2.6 Standard DLCs, 85 2.7 Session Identification and Addressing, 91 2.7.1 Session Identification in TYMNET, 92 2.7.2 Session Identification in the Codex Networks, 94 2.8 Error Recovery at the Network and Transport Layer, 95 2.8.1 End-to-End acks, Flow Control, and Permits, 96 2.8.2 Using End-to-End acks for Error Recovery, 98 2.8.3 The X.25 Network Layer Standard, 99 2.9 Summary, 101 2.10 Notes, Sources, and Suggested Reading, 102 PROBLEMS, 103 Chapter 3 DELAY MODELS IN DATA NETWORKS 111 3.1 Introduction, Ill 3.1.1 Multiplexing of Traffic on a Communication Link, 112 3.2 Queueing Models-Little's Theorem, 114 3.3 The M/M/1 Queueing System, 122 3.3.1 Main Results, 124 3.3.2 Occupancy Distribution Upon Arrival, 132 3.3.3 Occupancy Distribution Upon Departure, 134 3.4 The M/M/m, MIM/oo, and MIM/mIm Systems, 134