Dynamic Interfaces And Dynamic Subscriber Interfaces; Figure 16: Example Of A Dynamic Interface Stack - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - BROADBAND ACCESS CONFIGURATION GUIDE 2010-10-12 Configuration Manual

JunosE 11.3.x Broadband Access Configuration Guide

Dynamic Interfaces and Dynamic Subscriber Interfaces

596
10-Gigabit Ethernet (with and without VLANs)
GRE tunnels
For information about platform support for subscriber interfaces, see "Subscriber
Interfaces Platform Considerations" on page 601.
Dynamic interfaces are created automatically and transparently in response to external
events. For example, the router creates dynamic interfaces when a lower-layer link such
as an ATM or VLAN receives data. The layers of a dynamic interface are created based
on the packets received on the link and can be configured using profiles, RADIUS, or a
combination of the two. Dynamic interfaces are used to terminate Broadband Residential
Access Server (B-RAS) access such as: Point-to-Point Protocol over Ethernet (PPPoE),
Point-to-Point Protocol over ATM (PPPoA), and Point-to-Point Protocol over Ethernet
over ATM (PPPoEoA). A PPP session acts as logical separation between one subscriber
session and the next. Multiple services using policies and QoS can be applied to the IP
interface that is associated with the PPP session.
An example of a dynamic interface configuration is a PPPoE session running on top of a
Gigabit Ethernet VLAN interface. Figure 16 on page 596 shows an example of the dynamic
interface stack.

Figure 16: Example of a Dynamic Interface Stack

PPPoE minor interface
PPPoE major interface
VLAN subinterface
VLAN major interface
GE physical interface
You can configure the lower layers of the stack (GE physical interface and VLAN major
interface) either dynamically or statically, and dynamically configure the upper layers
(VLAN subinterface, PPPoE, and IP). An interface is considered dynamic if at least one
of the layers in the interface stack is configured dynamically.
The router creates dynamic subscriber interfaces (DSIs) on demand, in response to
external events, such as when a Dynamic Host Configuration Protocol (DHCP) event
occurs or when the router detects a packet. DSIs function in a manner similar to dynamic
interfaces. However, DSIs have a more specific application than dynamic interfaces. You
use DSIs when there are no PPPoE, PPPoA, or PPPoEoA sessions to provide separation
between layers and when subscriber management is required. For example, on an Ethernet
VLAN, multiple subscribers can enter the network from a Wi-Fi hotspot, as shown in
Figure 17 on page 597:
IP
Copyright © 2010, Juniper Networks, Inc.