Atmompls With L2Vpn Capability; Atmompls With L2Vpn Overview; Layer 2 Local Switching Overview; Atm Adaptation Layer 5 - Cisco CRS Configuration Manual

Implementing Point to Point Layer 2 services
The ISP requires provider edge (PE) routers with the following capabilities:
• Encapsulation of L2 protocol data units (PDU) into Layer 3 (L3) packets.
• Interconnection of any-to-any L2 transports.
• Emulation of L2 quality-of-service (QoS) over a packet switch network.
• Ease of configuration of the L2 service.
• Support for different types of tunneling mechanisms (MPLS, L2TPv3, IPSec, GRE, and others).
• L2VPN process databases include all information related to circuits and their connections.

ATMoMPLS with L2VPN Capability

These topics describe the ATM over MPLS (ATMoMPLS) with L2VPN feature:

ATMoMPLS with L2VPN Overview

The ATMoMPLS feature supports ATM Adaptation Layer 5 (AAL5) transport. ATMoMPLS is a type of
Layer 2 point-to-point connection over an MPLS core. ATMoMPLS and ATM local switching are supported
only for ATM-to-ATM interface-to-interface switching combinations.
To implement the ATMoMPLS feature, the Cisco CRS Router plays the role of provider edge (PE) router at
the edge of a provider network in which customer edge (CE) devices are connected to the Cisco CRS Router.

Layer 2 Local Switching Overview

Local switching lets you to switch Layer 2 data between two interfaces of the same type (for example,
ATM-to-ATM, or Frame Relay-to-Frame Relay) or between interfaces of different types (for example, Frame
Relay to ATM) on the same router, over an IP core network. The interfaces are on the same line card or on
two different cards. During these types of switching, Layer 2 address is used instead of the Layer 3 address.
In addition, same-port local switching lets you to switch Layer 2 data between two circuits on the same
interface.

ATM Adaptation Layer 5

AAL5 lets you transport AAL5 PDUs from various customers over an MPLS backbone. ATM AAL5 extends
the usability of the MPLS backbone by enabling it to offer Layer 2 services in addition to already existing
Layer 3 services. You can enable the MPLS backbone network to accept AAL5 PDUs by configuring the
provider edge (PE) routers at both ends of the MPLS backbone.
To transport AAL5 PDUs over MPLS, a virtual circuit is set up from the ingress PE router to the egress PE
router. This virtual circuit transports the AAL5 PDUs from one PE router to the other. Each AAL5 PDU is
transported as a single packet.
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
ATMoMPLS with L2VPN Capability
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