Avaya Configuring Dial Services Instrukcja Użytkownika Pobierz pdf (Strona 41)

Dial Services Overview

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Configuring Frame Relay to Work Optimally with Dial-on-Demand

How frame relay demand circuits operate depends on how your frame relay

service provider defines the user-to-network interface (UNI), the point between

the router and the service provider site. The service provider defines the UNI

dynamically or statically.

If the UNI is dynamic, it changes for each call. This means that the PVCs may be

different for each call, but they direct data to the same destination. The router

initially learns the PVCs when it calls the frame relay switch. If the UNI is static,

the user has defined the PVCs and can configure them for the router. The UNI

remains the same for all calls.

For a frame relay demand configuration to work well, follow these guidelines:

• You must have a PVC configured before you place a call.

For data to activate a demand circuit (instead of using Force Dial), the router

must learn at least one PVC from the frame relay switch before it can place a

call. However, to learn the PVCs, the router must call the switch, which it

cannot do.

For a dynamic UNI, you need to statically configure at least one PVC on the

router that is not configured for the switch. The static PVC acts as a “fake”

PVC that the router uses only to place an initial call to the switch. To

configure a static PVC, you set the frame relay data link connection identifier

(DLCI) to a number other than the number the switch provider assigns,

assuming you know the range of possible DLCIs. The static PVC is still valid

if you happen to use a number that the switch provider uses. For information

about configuring PVCs, see Configuring Frame Relay Services.

For a static UNI, the user configures the PVCs. A “fake” PVC is unnecessary.

• For a dynamic UNI, use the default frame relay service record. This service

record holds all PVCs that the router learns dynamically.

• Choose a network layer protocol that can retransmit data between the PVC

and the network if the data is lost.

Although the router makes a dial connection and starts sending data, the PVCs

do not always activate immediately. Consequently, you might lose data during

the first part of the transmission. Therefore, it is important to use protocols

that can account for this situation and ensure that any lost data can be sent

again. We strongly recommend using the Internet Protocol (IP) or the

Internetwork Packet Exchange (IPX).

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Avaya Configuring Dial Services Instrukcja Użytkownika Strona 41