Internet technologies and their applications in BASs - Intelligent Buildings and Building Automation - page 101

Table 6.2 Some application layer protocols and their applications

Application Protocols

File transfer FTP

Terminal emulation Telnet

Electronic mail SMTP

Network management SNMP

World Wide Web HTTP

Distributed file services NFS, XDR, RPC, X Windows

￿ Network File System (NFS), External Data Representation (XDR), and
Remote Procedure Call (RPC): Work together to enable transparent
access to remote network resources.
￿ Simple Mail Transfer Protocol (SMTP): Provides electronic mail
services.
￿ Domain Name System (DNS): Translates the names of network nodes
into network addresses.

6.3 Internet LAN vs WAN

6.3.1 A comparison between LAN and WAN

Local area networks (LANs) evolved following the revolution of PCs, as
discussed in Chapter 3. LANs enabled multiple users in a relatively small
geographical area to exchange files and messages, as well as to access shared
resources such as file servers and printers.
A wide area network is a data communications network that covers a

OSI Layers WAN Specifications

Frame
Relay

HDLC ISDN ATM

Data Link Layer

EIA/TIA-232
EIA/TIA-449
EIA-530

Physical Layer

etc.

V.24 V.35

Figure 6.5 Examples of WAN technologies at the two lowest layers of the OSI
Model.