# Configuring IPoA Dynamic Interfaces

E Series routers support dynamic IP over ATM (IPoA) interfaces. An IPoA interface is IP over ATM 1483 over ATM AAL5 over ATM. See Figure 46.

An IPoA configuration is typically used as a high-speed access service or uplink to another router. A common use is to provision IP over ATM circuits over DSL to connect businesses to the Internet—a B-RAS alternative to circuit aggregation. All provisioning can be through the RADIUS server to minimize any configuration of the router.

When IP packets are received over ATM circuits, the IP interfaces are dynamically constructed over the corresponding ATM 1483 interfaces from the configuration data received from the RADIUS server, a profile, or both.

Figure 54 shows the protocol layers that represent the IPoA interface columns, and the layers within the interface columns that are static and dynamic.

Figure 54: Dynamic IPoA over Static ATM 1483 Interface Columns

When you configure dynamic IPoA interfaces, you must assign a profile. Optionally, you can also assign a subscriber identification.

## Configuring a Dynamic IPoA Interface

To configure dynamic IPoA interfaces:

1. Configure a physical interface.
   host1(config)#interface atm 5/0
2. Configure an ATM subinterface.
   host1(config-if)#interface atm 5/0.1
3. Configure a PVC by specifying the VCD, the VPI, the VCI, and the encapsulation type.

   If you want the router to autodetect the encapsulation type, use the aal5autoconfig option.

   host1(config-subif)#atm pvc 10 100 22 aal5snap host1(config-subif)#atm pvc 10 100 22 aal5autoconfig
4. Assign a profile.
   host1(config-subif)#profile ip foo
5. (Optional) Assign subscriber identification.
   host1(config-subif)#subscriber ip user charlie domain myispname password lucy
6. Do either of the following:
   - Configure the subinterface to detect and accept the dynamic IP encapsulation type using the default lockout time range, 1–300 seconds.
     host1(config-subif)#auto-configure ip
   - Configure the subinterface to detect and accept the dynamic IP encapsulation type using a nondefault lockout time range. For example, the following command configures 3600 seconds (1 hour) as the minimum lockout time and 7200 seconds (2 hours) as the maximum lockout time.
     host1(config-subif)#auto-configure ip lockout-time 3600 7200
7. (Optional) Verify your configuration.
   host1#show atm subinterface atm 5/0.1

atm pvc

- Use to configure a PVC on an ATM interface. Specify one of the following encapsulation types:
  - aal5autoconfig—Enables autodetection of the 1483 encapsulation (LLC/SNAP or VC multiplexed).
  - aal5snap—Specifies an LLC encapsulated circuit; LLC/SNAP header precedes the protocol datagram.
  - aal5mux ip—Specifies a VC multiplexed circuit. This option is used for IP only.
- Example
  host1(config-subif)#atm pvc 6 0 11 aal5autoconfig
- Use the no version to remove the specified PVC.
- See atm pvc.

auto-configure

- Use to configure an ATM subinterface to support a dynamic interface. Specifies the types of dynamic encapsulation that the ATM 1483 subinterface detects and accepts.
- For detailed information about how to use this command, see auto-configure.
- Example 1—Enables autodetection for the IP encapsulation type using the default lockout time range, 1–300 seconds
  host1(config-subif)#auto-configure ip
- Example 2—Enables autodetection for the IP encapsulation type using a nondefault lockout time range, 3600–21600 seconds (1–6 hours)
  host1(config-subif)#auto-configure ip lockout-time 3600 21600
- Example 3—Disables encapsulation type lockout for the IP encapsulation type
  host1(config-subif)#auto-configure ip lockout-time none
- Example 4—Either command reenables encapsulation type lockout for the IP encapsulation type using the default lockout time range
  host1(config-subif)#auto-configure ip host1(config-subif)#no auto-configure ip lockout-time
- Example 5—Permanently locks out the IP encapsulation type until the auto-configure ip command is issued
  host1(config-subif)#no auto-configure ip
- Use the no version to terminate detection of the specified encapsulation type or, if the lockout-time keyword is specified, to restore the lockout time range to its default value, 1–300 seconds.
- See auto-configure.

interface atm

- Use to select an ATM interface or ATM 1483 subinterface.
- For information about specifying the ATM interface or subinterface, see interface atm.
- Examples
  host1(config)#interface atm 5/0.1 host1(config)#interface atm 4/0/2.1
- Use the no version to remove the interface or subinterface.
- See interface atm.

profile

- Use to assign a profile.
- You must specify the encapsulation type to which the profile applies: bridgedEthernet, ip, ppp, pppoe , or any.
- Specify a profile name with up to 80 alphanumeric characters.
- Example
  host1(config-subif)#profile ppp foo
- Use theno version to remove a profile assignment.
- See profile.

subscriber

- Use to configure a local subscriber on the E Series router to support authentication and configuration from RADIUS for a dynamic IPoA or bridged Ethernet interface.
- When you configure a subscriber, you must specify the following:
  - interfaceType—Type of dynamic interface, bridgedEthernet or ip
  - userNameUsage—How the dynamic interface uses the username for authentication purposes
    - user—Use the name as specified.
    - user-prefix—Use the name as a prefix to the interface physical location. The router automatically postpends the physical location of the user to the username string. The username format is userName.slot.port.vpi.vci. The resulting username string is then used to authenticate with the RADIUS server.
  - userName—RADIUS username
  - domainName—Domain name
- You may optionally supply password information:
  - passwordUsage—How the dynamic interface uses the password for authentication purposes
    - password—Use the password as specified.
    - password-prefix—Use the password as a prefix to the interface physical location. The router automatically postpends the physical location of the user to the password string. The password format is password.slot.port.vpi.vci. The resulting password string is then used to authenticate with the RADIUS server.
  - password—RADIUS password
- If your router is running stateful SRP switchover (high availability), the use of the subscriber command to configure RADIUS authentication for subscribers on dynamic bridged Ethernet interfaces might suspend stateful SRP switchover on the router or prevent stateful SRP switchover from becoming active. For more information about using the subscriber management application to bypass this limitation, see Authenticating Subscribers on Dynamic Bridged Ethernet over Static ATM Interfaces.
- Example 1
  host1(config-subif)#subscriber ip user-prefix charlie domain myisp password-prefix lucy
- Example 2
  host1(config-subif)#subscriber bridgedEthernet user westford003
  domain acmecorp.east password xyz123
- Use the no version to remove the subscriber.
- See subscriber.