Advanced WAN

X.25

• speed peaks at 64 Kbps - Newer versions can be up to 2 Mbps
• a set of protocols incorporated in a packet-switching network
• uses switches circuits and routes as available to provide the best routing at any particular time. The situation is always changing.
• uses telephone lines - slow - MUCH error checking => this is a major disadvantage
• synchronous packet-mode host or other device and the public data network (PDN) over a dedicated or leased-line circuit
• DTC/DCE interface
• a PAD is also needed - Packet Assembler / Disassembler
• And X.25 gateway is needed between the LAN and the Public Data Network
• See pic on p. 595.