I Figure 6-3: Points of Presence(POPs) Local Access and Transport Area ( LATA) Other Local area Local Long-Distance POP Carrier 1 Carrier a POP Sw itch E International CarrierⅩ Local Carrier 2 Sw itch Other Country Local Local In the U.s., competing Carrier 1 Carrier 2 carriers connect at Customer Customer points of presence(POPs) 6-11
6-11 Figure 6-3: Points of Presence (POPs) In the U.S., competing carriers connect at points of presence (POPs). Local Access and Transport Area (LATA) Local Carrier 1 Sw itch Local Carrier 2 Sw itch POP Local Carrier 1 Customer Local Carrier 2 Customer Other Local Area Other Country POP Long-Distance Carrier A International Carrier X
Page 282 Test Your understanding ·6b 6-12
6-12 • Page 282 • Test Your understanding • 6 b
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 6-13
6-13 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 6-14
6-14 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 6-15
6-15 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