Configuring frame relay over IP
To interconnect two frame relay networks across an IP network, Frame Relay over IP was developed. The idea is to create a GRE tunnel between frame relay networks to tunnel frame relay packets across the IP network, as shown in Figure 26.
Figure 26: Typical implementation of frame relay over IP
GRE tunneled frame relay packets include the following types:
FR packets that carry IP data
InARP packets
IND packets
LMI packets used for negotiating virtual circuit status in the GRE tunnel
You can configure static routes in interface view or configure PVCs in system view for frame relay switching.
Configuration restrictions and guidelines
The interfaces used for frame relay switching must be NNI or DCE.
Before configuring frame relay over IP network, it is necessary to create and configure a tunnel interface. After the GRE tunnel interface is set up, you can specify it for transmitting frame relay packets over IP network.
You must configure a static route for frame relay switching in frame relay interface view or multilink frame relay (MFR) interface view at both ends of the GRE tunnel, or configure a PVC for frame relay switching in system view. After that, the system adds two route entries to the frame relay routing table. In one route entry, the incoming interface is the tunnel interface and the outgoing interface is the frame relay interface. In the other route entry, the incoming interface is the frame relay interface and the outgoing interface is the tunnel interface. On the tunnel interface, a virtual circuit identified by out-dlci is also generated. The status of this virtual circuit determines the status of the two routes.
The virtual circuit must be assigned the same DLCI (out-dlci) on the tunnel interfaces at both ends of the GRE tunnel.
Configuration procedure
To configure frame relay over IP:
Step | Command | Remarks | |
|---|---|---|---|
1. Enter system view. | system-view | N/A | |
2. Create a tunnel interface in system view and configure the tunnel interface. | For more information about creating and configuring a tunnel interface, see Layer 3—IP Services Configuration Guide. | N/A | |
3. Return to system view. | quit | N/A | |
4. Enable frame relay switching. | fr switching | N/A | |
5. Enter interface view. | interface interface-type interface-number | N/A | |
6. Set the type of an interface for frame relay switching to NNI or DCE. | fr interface-type { dce | nni } | The default frame relay interface type is DTE, which does not support frame relay switching. | |
7. Configure frame relay switching either. | (Method 1) Configure static routes for frame relay switching in interface view. | fr dlci-switch in-dlci interface tunnel interface-number dlci out-dlci | By default, no static routes are configured for frame relay switching. You do not need to configure a static route on the tunnel interface. |
(Method 2) Configure a PVC for frame relay switching in system view. | 8. quit | N/A | |
9. fr switch name interface interface-type interface-number dlci dlci1 interface tunnel interface-number dlci dlci2 | By default, no PVC for frame relay switching exists. | ||
10. fr switch name | Optional. | ||
11. undo shutdown | Optional. By default, after a PVC is created, its status is up. | ||