Avaya Configuring Frame Relay Services Bedienungsanleitung PDF herunterladen (Seite 35)

Frame Relay Overview

117376-C Rev. 00

2-5

Frame Relay Packets

Figure 2-2 illustrates the structure of a frame relay packet. The packet’s header

field includes the following:

• Data link connection identifier (DLCI)

The DLCI is the virtual circuit identification number. The frame relay network

uses the DLCI to direct basic data flow. You configure the DLCI for PVCs.

For SVCs, the frame relay switch assigns the DLCI number on a per call

basis.

• Command/response bit (C/R)

ITU-T (formerly CCITT) standards do not use this bit.

• Forward explicit congestion notification (FECN) and backward explicit

congestion notification (BECN)

The FECN and BECN indicate congestion on the network. For information

about how the frame relay software uses these bits, see “Congestion Control,”

on page 2-22

• Discard eligibility (DE)

The DE bit allows the router to mark specific frames as low priority (discard

eligible) before transmitting them to the frame relay network.

• Extended address bit (EA)

The EA bit signals whether the next byte is part of the address. This bit

indicates the last byte of the DLCI.

1 2 ... 30 31 32 33 34 35 36 37 38 39 40 ... 239 240

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Avaya Configuring Frame Relay Services Bedienungsanleitung Seite 35