Subscriber Interfaces and IP Demux Overview

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You can create logical subscriber interfaces using static or dynamic IP demux interfaces. IP demultiplexing (demux) interfaces are logical interfaces that share a common, underlying logical interface. IP demux interfaces can be used to identify specific subscribers or to separate individual circuits.

The subscriber interfaces can provide different levels of services for individual subscribers in an access network. For example, you can apply CoS parameters for each subscriber.

Interface Sets of Static Demux Interfaces

Static demux interfaces can be grouped to create individual subscriber interfaces using interface sets. Interface sets enable you to provide the same level of service for a group of subscribers; for example, all residential subscribers who receive the basic data service.

Figure 6 shows a subscriber interface configured using a set of IP demux interfaces with an underlying VLAN interface.

Figure 6: IP Demux Subscriber Interface

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Dynamic Demux Interfaces

You can configure IP demux interfaces to represent a dynamic subscriber interface in a dynamic profile.

Demux interfaces are dynamically created by a DHCP access method when the underlying interface for the demux interface is configured for the access method. The DHCP access model creates the demux interface with the subscriber's assigned IP address.

To configure the demux interface in the dynamic profile, you specify variables for the unit number, the name of the underlying interface, and the IP address. These variables are replaced with the values that are supplied by DHCP when the subscriber logs in.

Guidelines for Configuring IP Demux Interfaces for Subscriber Access

When you configure static or dynamic IP demux interfaces for subscriber access, consider the following guidelines:

You can only configure interface sets of static IP demux interfaces and dynamic demux interfaces on MX-series routers. Hierarchical and per-unit scheduling is supported for dynamically created demux interfaces on the EQ DPC.
You can configure only one demux0 interface per chassis, but you can define logical demux interfaces on top of it (for example, demux0.1, demux0.2, and so on).
You must associate demux interfaces with an underlying logical interface.

Note: IP demux interfaces currently support only Gigabit Ethernet, Fast Ethernet, and 10-Gigabit Ethernet underlying interfaces.
You cannot use a dynamic demux interface to represent multiple subscribers in a dynamic profile attached to an interface. One dynamic demux interface represents one subscriber. Do not configure the aggregate-clients option when attaching a dynamic profile to a demux interface for DHCP.