Avaya Configuring Frame Relay Services Manual do Utilizador descarregar pdf (Página 22)

Configuring Frame Relay Services

2-2

117376-A Rev. A

Introduction

Frame relay is a high-speed, packet-switching WAN protocol that connects

geographically dispersed LANs. Frame relay is usually offered by a public

network provider; however, private organizations can acquire and manage their

own frame relay networks as well.

Frame relay is a connection-oriented protocol, which means that it relies on

existing end-to-end paths between devices connected across the network. It

implements these connections using

permanent virtual circuits (PVCs).

A PVC is a logical path the network provides to connect two devices. This path

between the source and destination point is a dedicated connection, so the PVC is

always available to the connected devices. Since many PVCs can coexist, devices

can share the bandwidth of the transmission line.

igure 2-1 illustrates a frame relay network.

Figure 2-1. Frame Relay Network

Frame relay assumes that networks use transmission lines with low error rates,

such as digital transmission media. Consequently, frame relay provides only basic

error detection with no error recovery. This minimizes the processing required for

each packet, allowing frame relay networks to operate at higher speeds with fewer

network delays.

Because frame relay performs only basic error checking, end stations running

upper-layer protocols such as Internet Protocol (IP) are responsible for resending

packets that did not transmit correctly the ﬁrst time.

Router

Frame relay

network

Router

VC=virtual circuit

Switch

Frame relay defines the interface between

the DTE (router) and the DCE (switch)

Switch

FR0001A

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