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    Example: Configuring Dynamic Subscriber Interfaces over Ethernet

    This example shows how you can configure a dynamic subscriber interface in an IP over Ethernet configuration by using DHCP events.

    Requirements

    This example uses the following software and hardware components:

    • JunosE Release 7.1.0 or higher-numbered releases
    • E Series router (ERX7xx models, ERX14xx models, the ERX310 router, the E120 router, or the E320 router)
    • ASIC-based line modules that support Fast Ethernet or Gigabit Ethernet

    Overview

    Figure 1 shows the interface stack built for this configuration.

    Figure 1: IP over Ethernet Dynamic Subscriber Interface Configuration

    IP over Ethernet Dynamic Subscriber Interface
Configuration

    Configuring Dynamic Subscriber Interfaces over Ethernet

    To configure a dynamic subscriber interface in an IP over Ethernet configuration by using DHCP events, perform the following steps:

    1. Configure the DHCP server.

      For instructions, see Configuring the DHCP Local Server.

    2. Specify a Fast Ethernet, Gigabit Ethernet, or 10-Gigabit Ethernet port.
      host1(config)#interface fastEthernet 4/1

      Use the no version to remove IP from an interface or subinterface. You must issue the no version from the highest level down; you cannot remove an interface or a subinterface if the one above it still exists.

    3. Create the primary IP interface by assigning an IP address and mask to the Ethernet interface (or make it unnumbered).
      host1(config-if)#ip address 192.168.2.1 255.255.255.0

      You must specify the layer 2 encapsulation before you set the IP address. Issuing this command creates the primary IP interface. You must create a primary IP interface on which to enable dynamic creation of subscriber interfaces.

      Use the no version to remove the IP address or to disable IP processing.

    4. Configure the primary IP interface to enable dynamic creation of subscriber interfaces.
      host1(config-if)#ip auto-configure ip-subscriber

      The router creates the required dynamic subscriber interfaces when the IP address is assigned to the associated subscriber. The address might be assigned by an external DHCP server, the DHCP local server, or the packet detect feature.

      Use the include-primary keyword to specify that the primary interface can be assigned to a subscriber. Use the exclude-primary keyword to specify that the primary interface is not used for subscribers. The primary interface is not assigned to a subscriber by default. You can issue this command from Interface Configuration mode, Subinterface Configuration mode, or Profile Configuration mode.

      Use the no version to disable creation of dynamic subscriber interfaces associated with this primary IP interface. Use the no version with the include-primary keyword to specify that the primary interface is not assigned to a subscriber.

    5. (Optional) Append the virtual router name to the subscriber interface in case of DSI configuration.
      host1(config-if)#ip auto-configure append-virtual-router-name

      You can use this command to allow more than one subscriber to have the same IP address across different virtual routers in the DSI configuration by appending the virtual router name to the interface. You can issue this command from either Interface Configuration mode or Profile Configuration mode.

      Use the no version to disable ip auto-configure on the static primary interface if it is already configured. This feature is enabled by default in a non-DSI configuration with the DHCP local server.

    6. (Optional) Specify the source address of traffic that is destined for the primary IP interface.
      host1(config-if)#ip source-prefix 192.168.2.1 255.255.255.0

      You can use this command to configure a subscriber interface or a primary IP interface enabled for dynamic creation of subscriber interfaces to demultiplex traffic with the specified source address. Use the no version to remove the association between the interface and the specified IP source address and mask.

    Published: 2014-08-20