# Configuring an NBMA Interface

You configure an ATM NBMA 1483 subinterface in a manner similar to configuring a standard ATM 1483 subinterface. When you specify a subinterface, however, you must select the multipoint option if you plan to add multiple circuits to form an NBMA interface. If you do not select multipoint, the subinterface defaults to point-to-point, and only a single circuit can be affiliated with that subinterface.

You can configure one or more PVCs and associate them with the subinterface you create. Also, you can enable InARP and identify a refresh rate on each specific circuit. For each NMBA interface, either InARP must be enabled, or a static map entry must be provided for each circuit owned by the interface; otherwise, transmitting over that circuit is impossible.

| Note: NBMA interfaces support only the aal5snap encapsulation.

To configure an NBMA interface:

1. Configure a physical interface.
   host1(config)#interface atm 2/0
2. Configure an ATM 1483 subinterface.
   host1(config-if)#interface atm 2/0.2 multipoint
3. Configure PVCs by specifying the VCD, VPI, VCI, and encapsulation type.
   host1(config-subif)#atm pvc 1 1 1 aal5snap inarp 10 host1(config-subif)#atm pvc 2 2 2 aal5snap
4. (Optional) Specify InARP and a refresh rate (also optional).
   host1(config-subif)#atm pvc 3 3 3 aal5snap inarp 5 host1(config-subif)#atm pvc 4 4 4 aal5snap inarp
5. Assign an IP address and subnet mask to the PVC.
   host1(config-subif)#ip address 192.32.10.20 255.255.255.0
6. (Optional) Use the appropriate show commands to verify your configuration.
   host1#show atm interface atm 2/0 host1#show atm map host1#show nbma arp atm 2/0 host1#show atm vc atm 2/0 2 host1#show atm subinterface atm 2/0.2