Specifications

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Cisco MWR 2941 Mobile Wireless Edge Router Release 3.5 Software Configuration Guide, Cisco IOS Release 15.1(3)MR
OL-26895-01
Chapter 8 Configuring IEEE 802.1Q Tunneling and Layer 2 Protocol Tunneling
Understanding VLAN Mapping
Router(config-if)# exit
Router(config)# vlan dot1q tag native
Router(config)# end
Router# show dot1q-tunnel interface gigabitethernet0/2
dot1q-tunnel mode LAN Port(s)
-----------------------------
Gi0/1
Router# show vlan dot1q tag native
dot1q native vlan tagging is enabled
There is no special configuration for provider trunk ports if the S-tags (outer VLAN tags) used in the
provider network have a TPID of 0x8100, the TPID used in 802.1Q tags. The provider trunk ports are
configured as normal trunk mode switch ports. If one of the other well known tunneling TPIDs is
required the dot1q tunneling ethertype tpid interface configuration mode command is used to change
it. Valid values for tpid are 0x88A8 (IEEE 802.1ad), 0x9100 and 0x9200. Use the no form of this
command to set the TPID back to the default setting of 0x8100.
Note The Cisco MWR 2941 does not currently support IEEE 802.1ad.
Understanding VLAN Mapping
Another way to establish S-VLANs is to configure VLAN mapping (or VLAN ID translation) on trunk
ports connected to a customer network to map customer VLANs to service-provider VLANs. Packets
entering the port are mapped to a service provider VLAN (S-VLAN) based on the port number and the
original customer VLAN-ID (C-VLAN) of the packet. Because the VLAN ID is mapped to the S-VLAN
on ingress, all forwarding operations are performed based on S-VLAN information.
Note The Cisco MWR 2941 only supports VLAN mapping on 802.1q tunnel ports.
Note When you configure features on a port that has VLAN mapping configured, you always use the S-VLAN
(translated VLAN) ID, not 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 back to the customer C-VLAN
occurs when packets exit the port.
There are three types of VLAN mapping on 802.1q tunnel ports:
• 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. The Cisco MWR 2941 does not currently support this
type of VLAN mapping.
• Selective QinQ—Maps the specified customer VLANs entering the tunnel port to the specified
S-VLAN ID. The S-VLAN is added to the incoming unmodified C-VLAN.