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Frame Relay Overview

117376-C Rev. 00

2-7

Management Protocols

Frame relay is an access protocol that runs between a router or data terminal

equipment (DTE) and a switch or data communications equipment (DCE). The

router and the switch use the Data Link Control Management Interface (DLCMI)

to exchange information about the interface and the status of each virtual circuit

(Figure 2-4)

Figure 2-4. Structure of the DLCMI

DLCMI supports three standard data link management specifications: LMI, ANSI

T1.617 Annex D, and CCITT (now ITU-T) Q.933 Annex A.

• The networking industry first developed the Local Management Interface

(LMI) specification. The LMI approach is asymmetric; the router sends a

status-inquiry message to the network, signaling that the router’s connection

to the network is functioning. The network replies with a status response.

• ANSI modified the LMI specification and incorporated it as Annex D to

ANSI standard T1.617. The ANSI method is generally similar to the LMI

approach.

• The CCITT (now ITU-T) modified the ANSI standard and adopted it as

Annex A to Q.933. The CCITT Annex A specification is similar to Annex D,

but it uses an international numbering scheme.

DLCMI DLCMI

Router

Frame

relay

Frame

relay

FR0004A

Network

node

switch

Network

node

switch

Network

node

switch

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Avaya Configuring Frame Relay Services Manual de usuario Pagina 37