WAN Services Facts

WAN Services Facts

Listed below are the most common WAN transmission media.

Carrier	Speed	Description
Plain Old Telephone Service (POTS)	56 Kbps	Existing wires use only one twisted pair Analog signals are used through the local loop A modem is required to convert digital signals to analog
T1 (a.k.a. DS1)	1.544 Mbps	T-Carrier is a digital standard widely deployed in North America. T1 lines usually run over two-pairs of unshielded twisted pair (UTP) cabling, although they can also run over other media such as coaxial, fiber-optic, and satellite. A T1 line has 24 channels (also known as DS0's) that each run at 64 Kbps. T3 lines usually run over fiber-optic cable. A T3 line has 672 channels that each run at 64 Kbps. A T1/T3 connection requires a CSU/DSU.
T3 (a.k.a. DS3)	44.736 Mbps
E1	2.048 Mbps	E-Carrier is a digital standard very similar to T-Carrier, but it is widely deployed in Europe. An E1 line has 32 channels (also known as DS0's) that run at 64 Kbps. An E3 line transmits 16 E1 signals at the same time. E1/E3 connections also require a CSU/DSU.
E3	34.368 Mbps
J1	1.544 Mbps	J-Carrier is a digital standard very similar to T-Carrier, but it is widely deployed in Japan. A J1 line is virtually identical to a T1 line. A J3 line has 480 channels that run at 32 Mbps. J1/J3 connections also require a CSU/DSU.
J3	32.064 Mbps

Note: WAN services also use fiber optic, wireless, satellite, and other transmission media. However, the use of these media to the local loop is not common at this time.

If your organization needs WAN connectivity, you can choose from the following service options:

Service	Bandwidth (Max.)	Line Type	Signaling Method	Characteristics
Public Switched Telephone Network (PSTN)	56 Kbps	POTS	Analog	Dialup over regular telephone lines
Leased lines	56 Kbps	POTS	Analog	Dedicated line with consistent line quality
X.25	64 Kbps	POTS	Analog	Dedicated line Variable packet sizes (frames) Ideal for low-quality lines
Frame Relay	1.54 Mbps	POTS T-1 T-3	Digital	Variable packet sizes (frames)
Asynchronous Transfer Mode (ATM)	1.2 Gbps	Coaxial, twisted pair, fiber-optic	Digital	Fixed-size cells (53-byte) High-quality, high-speed lines
Integrated Services Digital Network (ISDN)	144 Kbps (BRI) 4 Mbps (PRI)	POTS T-1	Digital	Basic rate operates over regular telephone lines and is a dialup service Primary rate operates over T-carriers
DSL	6.1 Mbps (1.544 or lower is more common)	POTS	Digital	Operates using digital signals over regular telephone lines DSL comes in many different flavors (such as ADSL and HDSL)

There is no clear distinction between WAN services such as Frame Relay and ISDN. For example, you can use Frame Relay protocol over ISDN lines. Once a device connects to the WAN cloud, internal protocols can convert data traffic into the necessary formats, then convert the data again at the other end.