Cisco Catalyst 3750 - Layer 2 VPN Application

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Catalyst 3750 Metro Switch Software Configuration Guide
78-15870-01
Chapter 1 Overview
Network Configuration Examples
Layer 2 VPN Application
You can use Catalyst 3750 Metro switches to form Layer 2 VPNs so that customers at different locations
can exchange information through a service-provider network, without requiring dedicated connections.
IEEE 802.1Q and Layer 2 protocol tunneling are features designed for service providers who carry traffic
of multiple customers across their networks and are required to maintain the VLAN and Layer 2 protocol
configurations of each customer without impacting the traffic of other customers.
The Catalyst 3750 Metro switches are used as the provider edge (PE) switches at the both edges of the
provider network connected to customer premises equipment (CPE) switches. The PE switches tag
packets entering the service-provider network with the customer VLAN ID. VLAN mapping translates
each customer VLAN ID to a service-provider VLAN ID for transport across the service-provider
network. At the egress PE interface, the egress PE switch restores the original VLAN ID numbers for
the customer’s network.
The service provider can use 802.1Q tunneling or EoMPLS to provide Layer 2 VPN services. If the
service-provider network is an MPLS cloud, and EoMPLS is configured as the point-to-point protocol,
MPLS tags are added at the ingress PE ES port that connects to the MPLS network. The MPLS tags are
removed at the ES port of the remote PE device.
See Chapter 13, “Configuring IEEE 802.1Q and Layer 2 Protocol Tunneling,” and Chapter 30,
“Configuring MPLS and EoMPLS,” for more information on configuring these features.
Figure 1-3 Layer 2 VPN Configuration
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VRF
interface
CPE
VLAN 50-120
VLAN 35-60
SP Metro core
SP VLAN 5
SP VLAN 8
PE
PE
VLAN 50-120
CPE
CPE
CPE
Customer
VLAN 35-60
Corp A, site 1
Corp B, site 2
Corp A, site 2
Corp B, site 3
Corp B, site 1
CPE
Customer
VLAN 50-120
PE
PE
SP VLAN 8
SP VLAN 8
SP VLAN 8
SP VLAN 8
SP VLAN 8
SP VLAN 8
SP VLAN 5
SP VLAN 5
SP VLAN 5
Catalyst 3750
Metro switch
Catalyst 3750
Metro switch
Catalyst 3750
Metro switch
Catalyst 3750
Metro switch