Leased Line and Frame Relay - WAN Basics

Leased lines are most cost-effective if a customer’s daily usage exceeds four to six hours. Leased lines offer predictable throughput with bandwidth typically 56 Kbps to 1.544 Mbps. They require one connection per physical interface (namely, a synchronous serial port).

 - One connection per physical interface
 - Bandwidth: 56 kbps–1.544 Mbps
 - T1/E1 and fractional T1/E1
 - Cost effective at 4–6 hours daily usage
 - Dedicated connections with predictable throughput
 - Permanent
 - Cost varies by distance

Frame Relay

Frame Relay provides a standard interface to the wide-area network for bridges, routers, front-end processors (FEPs), and other LAN devices. A Frame Relay interface is designed to act like a wide-area LAN- it relays data frames directly to their destinations at very high speeds. Frame Relay frames travel over predetermined virtual circuit paths, are self-routing, and arrive at their destination in the correct order.
Frame Relay is designed to handle the LAN-type bursty traffic efficiently.
The guaranteed bandwidth (known as committed information rate or CIR) is typically between 56 Kbps and 1.544 Mbps.
The cost is normally not distance-sensitive.

Connecting Offices with Frame Relay

Companies who require office-to-office communications, usually choose between a dedicated leased-line connection or a packet-based service, such as Frame Relay or X.25. As a rule, higher connect times make leased-line solutions more cost-effective.
Like ISDN, Frame Relay requires only one physical connection to the Frame Relay network, but can support many Permanent Virtual Circuits, or PVCs.

Frame Relay service is often less expensive than leased lines, and the cost is based on:

 - The committed information rate (CIR), which can be exceeded up to the port speed when the    capacity is available on your carrier’s network.
 - Port speed
 - The number of permanent virtual circuits (PVCs) you require; a benefit to users who need    reliable, dedicated connections to resources simultaneously.