• Describe the seven-layer model and realise how it applies to the real world.
• Evaluate and describe WAN technologies.
• Troubleshoot WANS.
• Use WANS to interconnect LANS.

Introduction
LANs, MANS and WANS. Protocols, the OSI seven layer model, ITU-T, ETSI, DTE, DCE, and the overall picture.

WANS
Dial up vs. Dedicated vs. packet switched networks and when to use them. Packet switching vs. circuit switching. Common WAN terms.

The PSTN
Analog, modems, Digital.

Leased lines
PCM, 64k, N*64, E1, TDM, Stat Mux, PDH, SDH, Data over voice, HDLC, PPP.

ISDN
Integrated digital network, BRI, PRI, dialup, topup, backup, Using the D channel for data.

xDSL
ADSL, HDSL.

X.25
PVCs, SVCs, LAPB, X.121 addressing, migration to other technologies.

Frame Relay
PVCs, SVCs, DLCI, LMI, CIR, EIR, FECN, BECN, traffic shaping, Voice over Frame Relay.

ATM
Cell switching principles, the physical layer, ATM switching, Virtual paths, QOS, CBR, VBR, ABR, UBR, AAL1 to AAL5, MPOA, LANE, Voice over ATM.

Other services
Satellite, Microwave, Wireless, SMDS, IP over SDH.

Routers
Network addressing, default gateways, multiprotocol routing, routing tables, routing protocols

The Internet
VPNs, IPSEC, QOS