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ATM for Subscriber Access Overview

By using the ATM Modular Interface Card (MIC) with small form-factor pluggable transceiver (SFP) and a supported Modular Port Concentrator (MPC), you can configure the MX Series router to support configurations that enable subscribers to access the router over an ATM network using ATM Adaptation Layer 5 (AAL5) permanent virtual connections (PVCs). Using these configurations enables the delivery of subscriber-based services, such as class of service (CoS) and firewall filters, for subscribers accessing the router over an ATM network.

Supported Configurations for ATM Subscriber Access

On MX Series routers with MPC/MIC interfaces that use the ATM MIC with SFP (Model Number MIC-3D-8OC3-2OC12-ATM), you can create the following configurations to enable subscribers to access the router over an ATM network using ATM Adaptation Layer 5 (AAL5) permanent virtual connections (PVCs):

  • Routed IP-over-ATM

  • Bridged IP-over-Ethernet-over-ATM

Routed IP-over-ATM Configurations

Routed IP-over-ATM (IPoA) configurations support statically created IPv4 and IPv6 logical subscriber interfaces over static ATM underlying interfaces. IPoA configurations are typically used to implement business digital subscriber line (DSL) connections that do not require connection negotiation for address assignment.

IPoA configurations require static configuration of the ATM underlying interface, IPv4 interface, IPv6 interface, CoS attributes, and firewall fiters. Dynamic configuration of these components is not supported.

To configure IPoA subscriber access, specify either of the following encapsulation types on the ATM underlying interface:

  • For IPoA encapsulation with logical link control (LLC), configure ATM subnetwork attachment point (SNAP) encapsulation (encapsulation atm-snap).

  • For IPoA encapsulation with virtual circuit (VC) multiplexing, configure ATM VC multiplex encapsulation (encapsulation atm-vc-mux).

Optionally, you can statically configure subscriber services such as CoS and firewall filters and apply them to the IPv4 or IPv6 interface; you cannot use a dynamic profile for this purpose.

Bridged IP-over-Ethernet-over-ATM Configurations

Bridged IP-over-Ethernet-over-ATM (IPoE-over-ATM) configurations support statically created IPv4 and IPv6 logical subscriber interfaces over static ATM underlying interfaces. Like IPoA configurations, IPoE-over-ATM configurations are typically used in topologies that do not require connection negotiation for address assignment.

For bridged IP-over-Ethernet-over-ATM configurations on an MX Series router, you must configure the ATM underlying interface with Ethernet-over-ATM LLC encapsulation (encapsulation ether-over-atm-llc).

IPoE-over-ATM configurations require static configuration of the ATM underlying interface, IP interface, CoS attributes, and firewall fiters. Dynamic configuration of these components is not supported. Optionally, you can statically configure subscriber services such as class of service (CoS) and firewall filters and apply them to the IPv4 or IPv6 interface; you cannot use a dynamic profile for this purpose.

Configuration and Encapsulation Types for ATM Subscriber Access

You use the same basic statements, commands, and procedures to create, verify, and manage IPoA and IPoE-over-ATM configurations.

A critical element of configuring ATM subscriber access is ensuring that you specify the correct encapsulation type for the ATM logical interface. The encapsulation type you use depends on the supported configuration and, for IPoA configuration, whether you want to configure an encapsulation type that uses logical link control (LLC) or virtual circuit (VC) multiplexing.

ATM Virtual Path Shaping on ATM MICs with SFP

On MX Series routers with Modular Port Concentrator (MPC) interfaces and an ATM Modular Interface Card (MIC) with small form-factor pluggable transceiver (SFP) installed, you can configure class of service (CoS) hierarchical shaping for the traffic carried on an ATM virtual path (VP). Traffic shaping helps you manage and regulate the traffic flow in your network by shaping the traffic on the VP to a specified rate. With traffic shaping, you can better control the traffic flow to avoid network congestion, and ensure that the traffic adheres to the class-of-service policies you set for it.

To configure hierarchical VP shaping on an ATM MIC with SFP (Model number MIC-3D-8OC3-2OC12-ATM), you must configure an interface set that consists of the ATM logical interface units on the ATM physical interface. The members of the interface set must all share the same virtual path identifier (VPI) and have different virtual circuit identifiers (VCIs). You then define one or more CoS traffic control profiles that include the ATM service category (atm-service) and the peak cell rate (peak-rate), sustained cell rate (sustained-rate), and maximum burst size (max-burst-size) parameters.

The ATM service category works in conjunction with the peak cell rate, sustained cell rate, and maximum burst size ATM cell parameters to shape the traffic leaving the interface. Finally, you apply a specified traffic control profile to the output traffic at the interface set and at each of its member ATM logical interfaces.

In the queueing model used for ATM VP hierarchical shaping on ATM MICs with SFP, the ATM physical interface functions as a level 1 scheduler node, the interface set containing the ATM logical interfaces functions as a level 2 scheduler node, and the ATM logical interfaces function as level 3 scheduler nodes.

The following configuration requirements apply to ATM VP shaping on ATM MICs with SFP:

  • All ATM interfaces that belong to the same interface set must share the same virtual path identifier (VPI) and have a unique virtual circuit identifier (VCI).

  • The ATM interface set can include only ATM interfaces. It cannot include Ethernet interfaces.

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