# Overview

Before you begin configuring dynamic interfaces in bulk, review the concepts described in this section.

Like upper-layer dynamic interfaces, bulk-configured dynamic interfaces are created automatically and transparently through the receipt of data over a lower-layer link, such as an ATM virtual circuit (VC) or a virtual LAN (VLAN) using autodetection. The layers of a dynamic interface are created based on the packets received on the link and can be configured through any one of the following:

- RADIUS authentication (through PPP or ATM 1483)
- Profiles
- A combination of RADIUS authentication and profiles

You create and configure each layer of a static interface manually through an existing configuration mechanism such as the command-line interface (CLI) or Simple Network Management Protocol (SNMP).

For more information about dynamic interfaces, autodetection, and RADIUS, see Overview in Configuring Dynamic Interfaces.

## Bulk Dynamic Interface Configurations

E Series routers support dynamic interfaces on two types of static interfaces: ATM and VLAN. This chapter provides configuration information for ATM and then for VLANs.

E Series routers support dynamic ATM 1483 subinterfaces over static ATM interfaces.

E Series routers support the following types of dynamic interfaces over VLAN major interfaces:

- Dynamic VLAN subinterface over static VLAN major interface
- IP over dynamic VLAN subinterface
- IP over PPPoE over dynamic VLAN subinterface

Internet Protocol version 4 (IPv4) is supported for all bulk-configured dynamic interface columns over dynamic ATM 1483 subinterfaces and over dynamic VLAN subinterfaces.

Currently, Internet Protocol version 6 (IPv6) is supported only when PPP or MLPPP is the layer immediately below the IPv6 layer in the interface column. IPv6 is not supported directly over dynamic ATM 1483, dynamic bridged Ethernet, or dynamic VLANs. Bulk-configured dynamic interface columns that support IPv6 include the following:

- Dynamic IPv6 over dynamic PPP over dynamic ATM 1483
- Dynamic IPv6 over dynamic MLPPP over dynamic ATM 1483
- Dynamic IPv6 over dynamic PPP over dynamic PPPoE over dynamic ATM 1483
- Dynamic IPv6 over dynamic MLPPP over dynamic PPPoE over dynamic ATM 1483
- Dynamic IPv6 over dynamic PPP over dynamic PPPoE over dynamic VLAN
- Dynamic IPv6 over dynamic MLPPP over dynamic PPPoE over dynamic VLAN

For more information about IPv4, see Configuring IP in JunosE IP, IPv6, and IGP Configuration Guide. For more information about IPv6, see Configuring IPv6 in JunosE IP, IPv6, and IGP Configuration Guide.

## Profiles

You can use profiles to configure dynamic interfaces over ATM and VLAN interfaces. A profile is a set of characteristics that can be dynamically assigned to interfaces. By using a profile, you reduce the management of a large number of interfaces by applying a set of characteristics to multiple interfaces.

When you are configuring a large number of interfaces with the same attributes at the higher layers, you can use a profile to factor out all the common attributes of each layer into one place. This action affects one or more dynamic layers of the interface column. After you define the static lower layers, you assign a profile to the highest static layer of the interface column.

When a dynamic interface is configured, the configuration data received from the RADIUS authentication server typically overrides configuration data obtained from a profile.

The atm atm1483 auto-configure command specifies the types of dynamic upper-interface encapsulations that are accepted or detected by a dynamic ATM 1483 subinterface. For flexibility, the router provides the ability to configure an ATM 1483 subinterface with distinct profile assignments for each encapsulation type supported by the atm atm1483 auto-configure command. For more information about using this command, see atm atm1483 auto-configure.

In contrast to dynamic ATM 1483 subinterfaces, dynamic VLAN subinterfaces support recognition and creation of simultaneous IP and PPPoE upper dynamic interface types. The vlan auto-configure command identifies the encapsulation type. For flexibility, the router provides the ability to configure a VLAN subinterface with distinct profile assignments for each encapsulation type supported by the vlan auto-configure command. For more information about using this command, see vlan auto-configure.

For more information about configuring profiles, see Configuring a Dynamic Interface from a Profile in Configuring Dynamic Interfaces.

## ATM Oversubscription for Bulk-Configured VC Ranges

You can take advantage of oversubscription of bulk-configured ATM VCs. The router supports oversubscription of bulk-configured VC ranges when you create a bulk-configured VC range on a static ATM AAL5 interface for use by a dynamic ATM 1483 subinterface.

Oversubscription of bulk-configured VC ranges works in a similar, but not identical, manner to oversubscription of static ATM 1483 subinterfaces that support dynamic upper-layer encapsulation types. For more information, see ATM Oversubscription for Dynamic Interfaces in Configuring Dynamic Interfaces.

### Bulk-Configured VC Ranges

An active bulk-configured VC range is associated with a dynamic ATM 1483 subinterface that supports a dynamic upper-layer encapsulation type. For ATM line modules that support VC oversubscription, the maximum number of active bulk-configured VCs per line module is less than the maximum number of individual VCs created from the total number of bulk-configured VC ranges that the line module supports. For information about configuring dynamic ATM 1483 subinterfaces with bulk-configured VC ranges, see Configuring ATM 1483 Dynamic Subinterfaces.

When the maximum number of active bulk-configured VCs has been reached, the router prevents all additional subscribers associated with the remaining inactive bulk-configured VCs from connecting to the line module until one of the following conditions occurs:

- At least one currently active subscriber logs out, which causes the router to tear down the dynamic interface column for that subscriber. Although the dynamic ATM 1483 subinterface and its associated VC remain configured on the router, the subinterface becomes inactive and can be replaced by one of the bulk-configured VCs waiting to become active.
- The router tears down at least one dynamic interface column in its entirety, which involves administratively shutting down the associated dynamic ATM 1483 subinterface.

When either of these conditions occurs, the router enables the first inactive bulk-configured VC that receives traffic to connect to the router as a replacement for the subscriber that logged out.

#### Example

Consider an ATM line module that supports a maximum of 32,000 individual VCs created from bulk-configured VC ranges, of which only 8000 VCs can be active at any one time. If all 32,000 bulk-configured VCs attempt to connect to the router, only the first 8000 VCs to receive traffic are able to log in, generate dynamic subinterface columns, and become active. When a subscriber connected through one of these active VCs logs out, the router enables the first of the remaining 24,000 inactive bulk-configured VCs that receives traffic to connect. The router replaces the inactive dynamic ATM 1483 subinterface and associated VC that remain after the subscriber logout with a new dynamic ATM 1483 subinterface and its newly activated circuit.

### Combination of Static ATM 1483 Subinterfaces and Bulk-Configured VC Ranges

ATM line modules are sometimes configured with a combination of static ATM 1483 subinterfaces and bulk-configured VC ranges. In these configurations, both the static ATM 1483 subinterfaces and bulk-configured VC ranges can support active subinterfaces. The combined total of active static ATM 1483 subinterfaces, and active dynamic ATM 1483 subinterfaces created from bulk-configured VC ranges, cannot exceed the maximum number of active subinterfaces supported by the line module.

The number of active dynamic subinterfaces created from the bulk-configured VC ranges is limited by both of the following:

- The number of static ATM subinterfaces that exist on the line module, which cannot exceed the maximum number of configured ATM 1483 subinterfaces supported on the line module.
- The number of static ATM subinterfaces that are active on the line module, which cannot exceed the maximum number of active ATM 1483 subinterfaces supported on the line module.

#### Example

Consider an ATM line module that supports a maximum of 8000 active ATM 1483 subinterfaces. The module has 4000 static ATM 1483 subinterfaces configured, all of which are active, and 8000 individual VCs created from bulk-configured VC ranges. Because the 4000 static ATM 1483 subinterfaces are already active, the router enables only 4000 of the bulk-configured VCs to create dynamic ATM 1483 subinterface columns and become active, yielding a combined total of 8000 active subinterfaces on the line module. The router prevents the remaining 4000 inactive bulk-configured VCs from connecting and becoming active until at least one subscriber connected through an active ATM subinterface logs out, thereby making the associated subinterface inactive and eligible for replacement.