Beta Draft Confidential
Configuring ATM Over MPLS Gateway Solution on CBX 3500
ATM Over MPLS Application Overview
ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000 1/19/059-5
PWE3 Over an MPLS Core Network
In this configuration, a Pseudo Wire (PW) is created to tunnel circuits between a local
and remote UNI port. This application uses a PWE3 standards-based Layer 2 VPN,
providing point-to-point connectivity between customer sites. The service provider
effectively emulates a set of wires between them. The customer can keep the same
Layer 2 connections to the service provider, but instead of data being carried natively
over an ATM or Frame Relay service, the traffic is encapsulated and routed over the
provider’s IP/MPLS backbone.
A PSN tunnel is created between the MPLS LERs (CBX 3500 switches). Using
Pseudo Wire Edge-to-Edge Emulation (PWE3) standards, the Layer 2 MPLS VPN
circuit (PW) is created from LER1 to LER 2. The signaling for PW setup is done using
targeted LDP operating in downstream unsolicited label retention mode. Multiple
PWs can be created over the PSN tunnel using N:1 encapsulation, maintaining a
one-to-one mapping between a native service and PW (i.e., N:1, N=1). However, in
this release, only one VC can be within the PW.
Figure 9-2 illustrates this application.
Figure 9-2. PWE3 Over MPLS Core Network
Supported Modules
This application is supported on the following CBX 3500 modules:
• 4-Port OC-12c/STM-4 IOA (on a POS ULC)
• 1-Port OC-48c/STM-16 IOA (on a POS ULC)
• Other vendor switches that support ATM and PWE3
IP/MPLS Core
CBX 3500 CBX 3500
PE to PE E-LSP
CE
CE
A
T
M
F
R
CE
CE
A
T
M
F
R
(PSN Tunnel)
LER1
PW Control Plane
over LDP
Pseudo Wires
AT M P OS
LER2
AT MPOS
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