Example: Configuring Dynamic Subscriber Interfaces over GRE Tunnels

Requirements

• 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: GRE Tunnel Dynamic Subscriber Interface Configuration

Configuring Dynamic Subscriber Interfaces over GRE Tunnels

Step-by-Step Procedure

1. Create a GRE tunnel interface.

   For instructions, see the Configuration Tasks section in JunosE IP Services Configuration Guide .

2. Create the primary IP interface by assigning an IP address and mask to the bridged Ethernet interface (or make it unnumbered).
   host1(config-subif)#ip address 192.168.2.20 255.255.255.0

   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.

3. Configure the packet detect feature and specify that IP automatically detect packets that do not match any entries in the demultiplexer table.
   host1(config-if)#ip auto-detect ip-subscriber

   When an unmatched packet is detected, an event is generated that determines whether to create a dynamic subscriber interface.

   Use the no version to restore the default, in which packet detection is disabled.

4. Configure the primary IP interface to enable dynamic creation of subscriber interfaces.
   host1(config-subif)#ip auto-configure ip-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
6. (Optional) Specify the IP inactivity timer.
   host1(config-subif)#ip inactivity-timer 100

   A dynamically created subscriber interface is deleted if it is inactive for a period longer than the inactivity timer value. The timer value can be in the range 1–65335 minutes. A timer value of 0 specifies that dynamically created subscriber interfaces are never deleted by the inactivity timer.

   Use the no version to restore the default, in which inactivity timer feature is disabled.

7. (Optional) Specify the source address of traffic that is destined for the primary IP interface.
   host1(config-subif)#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.