Figure 16: Example Of A Dynamic Interface Stack; Dynamic Interfaces And Dynamic Subscriber Interfaces - Juniper JUNOSE 11.1.X - BROADBAND ACCESS CONFIGURATION GUIDE 6-4-2010 Configuration Manual

JUNOSe 11.1.x Broadband Access Configuration Guide
For information about platform support for subscriber interfaces, see "Subscriber
Interfaces Platform Considerations" on page 609.

Dynamic Interfaces and Dynamic Subscriber Interfaces

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 604 shows an example of the
dynamic interface stack.

Figure 16: Example of a Dynamic Interface Stack

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.
604
Subscriber Interfaces Overview
10-Gigabit Ethernet (with and without VLANs)
GRE tunnels
IP
PPPoE minor interface
PPPoE major interface
VLAN subinterface
VLAN major interface
GE physical interface