Leased Line

Two common type of leased lines used for private voice and/or data networking are

T1 and T3

both can operate over either copper or fiber optic.

T1 was developed by AT&T in 1960s, offer same same data rate as symmetric DSL (1.544Mbps), it can carry 24 digitized voice channels. If it's being used for telephone conversation, it plugs into the office phone system, if it's carrying data it plugs into the network's router.

T3 are a common aggregation of 28 T1 circuits that yields 44.736Mbps total network bandwidth.

A large company probably needs something more than a T1 line. Some of common lines designation:

• DS0 - 64 kilobits per second
• ISDN - Two DS0 lines plus signaling (16 kilobytes per second), or 128 kilobits per second
• T1 - 1.544 megabits per second (24 DS0 lines)
• T3 - 43.232 megabits per second (28 T1s)
• OC3 - 155 megabits per second (84 T1s)
• OC12 - 622 megabits per second (4 OC3s)
• OC48 - 2.5 gigabits per seconds (4 OC12s)
• OC192 - 9.6 gigabits per second (4 OC48s)

Configuring Leased Line (Cisco)

1. configure IP

2. HDLC and PPP configuration

- make sure configure same WAN data-link protocol on each end of the serial link