3Com 10014299 manual Configure Frame Relay over Isdn, Configure the Frame Relay-related commands

272CHAPTER 17: CONFIGURING FRAME RELAY

A DCE device provides Frame Relay switching. Its one end is connected to a DTE device via ISDN, and the other end is directly connected to another DTE device, as shown in the following figure:

Figure 91 Frame Relay switching connection between DTE devices

DTE		ISDN	DCE	DTE
		Switch
	Bri0	Pri	S1	S1
	Bri1		Router B
Router A			Frame Relay	Router C
			Switching

The DCE device cannot originate a call, since the PVC segment that the DCE device establishes via ISDN can only be activated through dialing. The call can only be originated by the DTE device, which is connected to ISDN. After the call is successfully made, the corresponding PVC segment is established for transmitting the network layer data.

If legacy BDR is adopted on the ISDN interface worked with Frame Relay on the DCE device, the calling party will use the configured dial string to make an ISDN call to the DCE device. If dialer profiles are adopted, the calling party (the DTE device) will re-configure the selected available B channel with the link layer protocol on the dialer interface, and then use the configured dial string to make an ISDN call to the DCE device.

After a physical B channel is set up, Frame Relay LMI and inverse ARP process will start. If an agreement is reached through the negotiation, the corresponding PVC will be established. Then, the DCE device will look for another PVC segment according to the Frame Relay switching configuration and activate the PVC segment. When both PVC segments are in active status, it means that the whole PVC is set up. In this case, Frame Relay can be adopted on the B channel to carry the network layer data.

Distinguished from legacy BDR, dialer profiles require a called party to search for the dialer interface according to the dialing number in the ISDN packet, and hence obtain the link layer protocol type for the B channel. Then, the called party can dynamically configure the dialer interface or physical ISDN interface and initialize it.

Configure Frame Relay over ISDN

Frame Relay over ISDN provides a means for accessing devices from ISDN to a Frame Relay network. Its implementation fully depends on the techniques of Frame Relay and BDR. This section only covers the Frame Relay over ISDN-related commands. For configuration details and commands, refer to the Frame Relay and BDR Configuration in this manual.

1Related Frame Relay Configuration

Only some simple Frame Relay configurations are covered in this section. For other configurations, refer to the Link Layer Protocol.

Perform the following configuration in synchronous serial interface view.

Table 313 Configure the Frame Relay-related commands

Operation

Command