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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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Chapter 1 Overview
Network Configuration Examples
Layer 2 VPN Application
Enterprise customers need not only high bandwidth, but also the ability to extend their private network
across the service provider’s shared infrastructure. With Ethernet in the WAN network, service providers
can meet the bandwidth requirements of enterprise customers and use VPN features to extend customers’
networks.
Enterprise customers can use Layer 2 VPN to transparently move any type of traffic across a
service-provider network, and create virtual pipes across the service provider infrastructure. In contrast
to Layer 3 VPN service, Layer 2 VPN lowers operational expenses by minimizing enterprise user-facing
provider edge (UPE) switch configuration and management. You can use Cisco ME 3400 switches to
form Layer 2 VPNs so that customers at different locations can exchange information through a
service-provider network without requiring dedicated connections.
In Figure 1-2, Cisco ME 3400 switches are used as UPEs in customer sites connected to
customer-premises equipment (CPE) switches. The switches can tag customer traffic with the
service-provider VLAN ID on top of the customer’s IEEE 802.1Q tag. By supporting double tags, the
Cisco ME 3400 switch provides a virtual tunnel for each customer and prevents VLAN ID overlaps
between customers. In addition to data-plane separation, the Cisco ME 3400 switch can also tunnel the
customer’s control protocols. With Layer 2 protocol tunneling, the switch can encapsulate each
customer’s control-plane traffic and send it transparently across the service-provider network.
See Chapter 13, “Configuring IEEE 802.1Q and Layer 2 Protocol Tunneling,” for more information on
configuring these features.
Figure 1-2 Layer 2 VPN Configuration
92997
CPE
VLAN 50-120
VLAN 35-60
SP Metro core
SP VLAN 5
SP VLAN 8
UPE
UPE
UPE
UPE
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
Customer building
UPE = Cisco ME 3400 switch
CPE
Customer
VLAN 50-120
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
Customer building
Customer building
Customer building