CAS CL5000J Series Manuel d'utilisateur télécharger pdf (Page 74)

Gateway

A gateway can translate information between different network data formats or network architectures. It can

translate TCP/IP to AppleTalk so computers supporting TCP/IP can communicate with Apple brand computers.

Most gateways operate at the application layer, but can operate at the network or session layer of the OSI

model. Gateways will start at the lower level and strip information until it gets to the required level and

repackage the information and work its way back toward the hardware layer of the OSI model.

TCP/IP

The part of the network that does the job of transporting and managing the data across the network is called

TCP/IP which stands for Transmission Control Protocol (TCP) and Internet Protocol (IP). There are other

alternative mechanisms for managing network traffic, but most, such as IPX/SPX for Netware, will not be

described here in much detail. The IP layer requires a 4 (IPv4) or 6 (IPv6) byte address to be assigned to each

network interface card on each computer. This can be done automatically using network software such as

dynamic host configuration protocol (DHCP) or by manually entering static addresses into the computer.

UDP

User Datagram Protocol (UDP) supports the network at the transport layer. User Datagram Protocol (UDP) is an

unreliable connection-less protocol and is defined by RFC 768 and 1122. It is a datagram service. There is no

guarantee that the data will reach its destination. UDP is meant to provide service with very little transmission

overhead. It adds very little to IP data packets except for some error checking and port direction (Remember,

UDP encapsulates IP packets).

DHCP

This protocol is used to assign IP addresses to hosts or workstations on the network. Usually a DHCP server on

the network performs this function. Basically it "leases" out address for specific times to the various hosts. If a

host does not use a given address for some period of time, that IP address can then be assigned to another

machine by the DHCP server. When assignments are made or changed, the DHCP server must update the

information in the DNS server.

Access Point

Wireless access points (APs or WAPs) are specially configured nodes on wireless local area networks (WLANs).

Access points act as a central transmitter and receiver of WLAN radio signals.

Access points used in home or small business networks are generally small, dedicated hardware devices

featuring a built-in network adapter, antenna, and radio transmitter. Access points support Wi-Fi wireless

communication standards.

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CAS CL5000J Series Manuel d'utilisateur Page 74