Wide Area Networks
MANs and WANs are typically built by using leased circuits from common
carriers such as Chorus Ltd.
They can provide:
- data over voice
- voice over data
WANs can use common carrier networks:
- Circuit-Switched Networks
- Dedicated-Circuit Networks
- Packet-Switched Networks
WANs can also use Public Networks:
- Virtual Private Networks
Oldest and simplest WAN approach
- POTS – Plain Old Telephone Service
- ISDN – Integrated Services Digital Network
Simple, flexible and inexpensive
Low data transmission rates
Leased full duplex circuits from common carriers
To create point to point links between organizational
- Mesh Synchronous Optical Network (SONET)
ANSI standard for optical fiber transmission in Gbps range.
Begins with OC-1 at 51.84 Mbps
Goes up to OC-3072 at 159.25 Gbps
Packet Switched Networks
Enable multiple connections to exist simultaneously between computers
over the same physical circuits.
- connectionless – Datagram
- connection-oriented – Virtual Circuit
Types of Virtual Circuits:
Permanent Virtual Circuit – common, established for long duration.
Switched Virtual Circuit – established dynamically on a per call basis.
Asynchronous Transfer Mode (ATM)
Provides packet switching service, type of service protocol
- performs encapsulation of packets
- Provides no error control
- Scalable, easy to multiplex