I Figure 6-4: Circuit Switching The Pstn has traditionally used circuit sw itching a circuit is an end-to-end connection between two subscribers Capacity is reserved on all trunk lines and sw itches along the w ay 日日 Capacity must be paid for even if it is not used 6-11
6-11 Figure 6-4: Circuit Switching A circuit is an end-to-end connection betw een tw o subscribers. Capacity is reserved on all trunk lines and sw itches along the w ay. Capacity must be paid for even if it is not used. The PSTN has traditionally used circuit sw itching
Figure 6-5: Voice and Data Traffic Full-Duplex(TWo-Way) Circuit Voice traffic. Fairly Constant Use Circuit Switching Is Fairly Eficient Full-Duplex(Two-Way) Circuit Data traffic Short Bursts ong Silences Circuit Switching Is Inefficient The reserved capacity of circuit switching is OK for voice, but not for bursty data transmission 6-12
6-12 Figure 6-5: Voice and Data Traffic Full-Duplex (Two-Way) Circuit Voice Traffic: Fairly Constant Use; Circuit Switching Is Fairly Efficient Data Traffic: Short Bursts, Long Silences; Circuit Switching Is Inefficient Full-Duplex (Two-Way) Circuit The reserved capacity of circuit switching is OK for voice, but not for bursty data transmission
Figure 6-6: Dial-Up circuits Versus Leased Line Circuits Dial-Up circuits Leased line circuits Operation Dial-Up. Separate Permanent circuit circuit for each call always on Up to 56 kbps Speed for Carrying Residence can only 56 kbps to gigabit Data Send up to 33.6 kbnospeeds Number of voice One Several due to Calls multiplexed multiplexing There are two types of circuits between customer premises ordinary dial-up circuits and leased line circuits 6-13
6-13 Figure 6-6: Dial-Up Circuits Versus Leased Line Circuits Dial-Up Circuits Leased Line Circuits Operation Dial-Up. Separate circuit for each call. Permanent circuit, always on. Speed for Carrying Data Up to 56 kbps Residence can only Send up to 33.6 kbps 56 kbps to gigabit speeds Number of Voice Calls Multiplexed One Several due to multiplexing There are two types of circuits between customer premises: ordinary dial-up circuits and leased line circuits
I Figure 6-7: Local Loop Technologies echnology Use Status 1-Pair Voice-Grade Residences Already installed UTP 2-Pair Data-Grade Businesses for Must be pulled to the UTP LoWest-speed customer premises access lines (this is expensive) Optical Fiber Businesses for Must be pulled to the higher-speed customer premises access lines (this is expensive Residential 1-pair voice-grade UTP is already installed This makes it inexpensive to use Business 2-pair data-grade UTP and fiber for leased lines must be installed; this is expensive 6-14
6-14 Figure 6-7: Local Loop Technologies Technology Use Status 1-Pair Voice-Grade UTP Residences Already installed 2-Pair Data-Grade UTP Businesses for Lowest-speed access lines Must be pulled to the customer premises (this is expensive) Optical Fiber Businesses for higher-speed access lines Must be pulled to the customer premises (this is expensive) Residential 1-pair voice-grade UTP is already installed. This makes it inexpensive to use Business 2-pair data-grade UTP and fiber for leased lines must be installed; this is expensive
Figure 6-8: Analog Telephone Transmission Analot (Analogous) Electrical Signal Sound Wave Analog signals rise and fall in intensity with the human voice No resistance to errors as there is in digital transmission Initially, the entire Pstn was analog 6-15
6-15 Figure 6-8: Analog Telephone Transmission Sound Wave Analog (Analogous) Electrical Signal Analog signals rise and fall in intensity with the human voice. No resistance to errors as there is in digital transmission. Initially, the entire PSTN was analog