ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000 13-1
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13
Configuring Layer 2 VPNs
Layer 2 Virtual Private Network (VPN) is an optional software feature that enables 
network providers to dedicate resources for those customers who require guaranteed 
performance, reliability, and privacy. This feature is sometimes called Application 
Specific Routes (ASRs) or Customer Specific Routes (CSRs).
A Layer 2 VPN enables you to provide dedicated bandwidth to the customer. When 
you configure a trunk, you can dedicate it to a specific VPN and, if desired, allow 
customers to monitor their own networks. However, switch control and configuration 
stays with you as the network provider.
Layer 2 VPNs support PNNI links. See “Layer 2 VPNs Over PNNI” on page 13-10 for 
more information.
Policy-based routing is supported on the CBX 3500, CBX 500, GX 550, and B-STDX 
9000 switches. While the B-STDX 9000 does not support PNNI links directly, it 
supports the configuration, origination, and termination of Layer 2 VPN circuits from 
CBX/GX switches that do support PNNI links.