Deployment Example - Cisco Catalyst 4500 Series Software Configuration Manual

Chapter 30 Configuring 802.1Q Tunneling, VLAN Mapping, and Layer 2 Protocol Tunneling
One way to establish translated VLAN IDs (S-VLANs) is to map customer VLANs to service-provider
VLANs (called VLAN ID translation) on trunk ports connected to a customer network. Packets entering
the port are mapped to a service provider VLAN (S-VLAN) based on the port number and the packet's
original customer VLAN-ID (C-VLAN).
Service providers's internal assignments might conflict with a customer's VLAN. To isolate customer
traffic, a service provider could decide to map a specific VLAN into another one while the traffic is in
its cloud.

Deployment Example

In Figure
The service provider separates the data and control traffic between the two customers and from the
providers' own control traffic. The service provider network must also be transparent to the customer
edge devices.
Figure 30-4
Cat4K
Customer A
edge switch
Cat4K
Customer B
edge switch
Cat4K
Customer B
edge switch
All forwarding operations on the Catalyst 4500 series switch are performed using S-VLAN and not
C-VLAN information because the VLAN ID is mapped to the S-VLAN on ingress.
When you configure features on a port configured for VLAN mapping, you always use the S-VLAN
Note
rather than the customer VLAN-ID (C-VLAN).
On an interface configured for VLAN mapping, the specified C-VLAN packets are mapped to the
specified S-VLAN when they enter the port. Symmetrical mapping to the customer C-VLAN occurs
when packets exit the port.
The switch supports these types of VLAN mapping on UNI trunk ports:
•
30-4, the service provider provides Layer 2 VPN service to two different customers, A and B.
Layer 2 VPN Deployment
VLAN translation
configured TRUNK
PORTS
SP
Cat4K
One-to-one VLAN mapping occurs at the ingress and egress of the port and maps the customer
C-VLAN ID in the 802.1Q tag to the service-provider S-VLAN ID. You can also specify that packets
with all other Vlan Ids are dropped. See the
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
SP
Cat4K Cat4K
SP Network
"One-to-One Mapping" section on page
About VLAN Mapping
VLAN translation
configured TRUNK
PORTS
Cat4K
Customer A
edge switch
SP
Cat4K
Customer B
edge switch
30-10.
30-7