WAN and VLAN Solutions

WAN technology development

Data pathways used in WAN communications links

Circuit switching requires a dedicated physical connection between each communication endpoint.

Virtual circuit switching forms a logical connection between each communication endpoint.

ISDN (Integrated Services Digital Network)

Each ISDN channel has 64 Kbps capacity:

T-carrier leased lines

Commonly used T-carrier leased lines:

SONET (Synchronous Optical Network)

SONET networks:

The European counterpart to SONET is known as SDH (Synchronous Digital Hierarchy).


The maximum capacity of X.25 networks is 56 Kbps. It was one of the original packet switching technologies, which was particularly successful with supply chain networks.

Frame Relay

Frame Relay improved on X.25 by using virtual circuits and smaller variable-length packets to deliver capacity of up to 1.544 Mbps.

ATM (Asynchronous Transfer Mode)

ATM is similar to Frame Relay because it uses virtual circuits and it improved on it by using fixed length cells to deliver capacity of up to 622 Mbps.

Internet VPN (Virtual Private Network)

Internet VPN uses encryption to establish a virtual circuit running over IP networks.