Cisco Ios Isdn Commands

Cisco routers support ISDN. The commands most often used to enable data and voice communications over ISDN are listed in Table 2-15.

Table 2-15 ISDN Commands

IOS Command

Description

isdn caller phone-number

The number called by the router. The phone-number is the remote router's ISDN number.

isdn calling-number calling-number

The number of the device making the outgoing call; only one entry is allowed.

isdn switch-type

ISDN service provider switch type.

NOTE Frame Relay is a Layer 2 protocol that provides connectionless delivery between devices.

Frame Relay, although not listed in the official blueprint for the CCIE Security written exam, has a few terms you should be aware of for the exam:

• Forward explicit congestion notification (FECN)—A bit set by a Frame Relay network to inform DTE receiving the frame that congestion was experienced in the path from source to destination. DTE receiving frames with the FECN bit set can request that higher-level protocols take flow-control action, as appropriate.

• Backward explicit congestion notification (BECN)—A bit set by a Frame Relay network in frames traveling in the opposite direction of frames encountering a congested path. DTE receiving frames with the BECN bit set can request that higher-level protocols take flow-control action, as appropriate. The ISP or WAN switches typically set FECN/BECN.

• Data-link connection identifier (DLCI)—A value that specifies a PVC or SVC in a

Frame Relay network. DLCIs are locally significant. Globally significant DLCIs are used for LMI communication between Frame Relay switches.

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