# Creating an IP Interface

You can configure IP interfaces that support the following configurations:

- Configuring Single PPP Clients per ATM Subinterface
- Configuring Multiple PPP Clients per ATM Subinterface

## Configuring Single PPP Clients per ATM Subinterface

Figure 3 shows a conceptual view of the configuration of a single PPP client per ATM subinterface.

Figure 3: Single PPP Clients per ATM Subinterface

Configure an ATM interface by entering Configuration mode and performing the following tasks. For more information about configuring ATM interfaces, see JunosE Link Layer Configuration Guide.

1. Configure a physical interface.
   host1(config)#interface atm 0/1
2. Configure the subinterface.
   host1(config-if)#interface atm 0/1.20
3. Configure a permanent virtual circuit (PVC) by specifying the vcd (virtual circuit descriptor), the vci (virtual channel identifier), the vpi (virtual path identifier), and the encapsulation type.
   host1(config-if)#atm pvc 10 22 100 aal5snap
4. Configure PPP encapsulation.
   host1(config-if)#encapsulation ppp
5. Configure PAP or CHAP authentication.
   host1((config-if))#ppp authentication chap
6. Assign a profile to the PPP interface.
   host1(config-subif)#profile foo

## Configuring Multiple PPP Clients per ATM Subinterface

Figure 4 shows how PPPoE supports multiplexing of multiple PPP sessions per ATM subinterface.

Figure 4: Multiple PPP Clients per ATM Subinterface

Configure an ATM interface by entering Configuration mode and performing the following tasks. For more information about configuring ATM interfaces, see JunosE Link Layer Configuration Guide.

1. Configure a physical interface.
   host1(config)#interface atm 0/1
2. Configure the subinterface.
   host1(config-if)#interface atm 0/1.20
3. Configure a PVC by specifying the vcd (virtual circuit descriptor), the vci (virtual channel identifier), the vpi (virtual path identifier), and the encapsulation type.
   host1(config-if)#atm pvc 10 22 100 aal5snap
4. Configure PPPoE encapsulation.
   host1(config-if)#encapsulation pppoe
5. Configure the subinterface for one PPP client.
   host1(config-if)#interface atm 0/1.20.1
6. Configure PPP encapsulation.
   host1(config-if)#encapsulation ppp
7. Configure PAP or CHAP authentication.
   host1((config-if))#ppp authentication chap
8. Apply the profile to the PPP interface.
   host1(config-subif)#profile foo2
9. Configure the subinterface for a second PPP client.
   host1(config-if)#interface atm 0/1.20.2
10. Configure PPP encapsulation.
    host1(config-if)#encapsulation ppp
11. Configure PAP or CHAP authentication.
    host1((config-if))#ppp authentication chap
12. Apply the profile to the PPP interface.
    host1(config-subif)#profile foo2