Wide Area Network (WAN)
Data Link Layer + Network Layer
1. PSTN – Public Switched Telephone Network
a. PON – Passive Optical Network
i. PSTN is designed for voice transmission
ii. Is used with modem for data transmission
iii. Older PSTN had a Max 56 kbps of speed
iv. PSTN defines:
2. Central Office
4. Local loop
a. Home telephone Local Loop Central Office International
b. E.g (416)-In Toronto, (222) – Local, (1111) – Phone ID
c. This is an Analog System
d. Digital Local Loop uses passive fiber optic called (PON)
e. PXB (Private Exchange Branch)
2. ISDN (Digital System)
a. RJ 13
b. 2 types of digital connection provided by ISDN:
i. Basic & Primary.
ii. ISDN Defines a digital line as 64 k/s Data Channel. (DS0 Digital Subscriber Line
iii. BRI (Basic Rate Interface ISDN)
1. Has 2 64k Data Channel Called B-Channel 128kb/s
2. b-bits Network Speed, B- Bytes for file on a disk.
3. IDSN D channel & 2 B Channels.
a. *~Note. D-Channel cannot be used for data transmission; the
channels are used for flow control & error handling.
4. PRI (Primary Rate Interface ISDN)(Best Example of a 1-800 #) if one line
is currently being used, it will go to the next line)
a. Provides a max speed of 1.544 Mbps
b. It has 23-B channel (64k each)
c. It has one D-Channel (64k)
i. IDSN PRI D-Channel(64k/s) & 23 B-Channel
ii. IDSN System is used for both data & voice transmission
( Digital Format)
3. Digital Lines T1, T3 (Dedicate Line) a. T1:
i. Speed: 1.544m/s
ii. T1 Modem is called DSU/CSU, Data Server Unit, Customer Server Unit.
iii. T1: is a secure, dedicated customer line.
iv. E.g. Toronto office Remote Office in LA, use a T1 Connection. (requires 2
modems, DSU/CSU along the T1 line connection)
v. T1 defines Smart Jack
vi. *~Note. The speed of T3 is 45 Mb/s
vii. Note*~ PSTN, ISDN, T1/T3 Carriers are based on layer 2 OSI.
4. XDSL (Digital Subscriber Line)
a. 2 Types of DSL (Cable Modem)
i. ASDL (Asynchronous DSL) (Home Us