Lesson 6: WAN Basics
WAN Basics
| Transmission
Options | WAN
Requirements & Solutions
Leased Line
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.
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