Cisco 350 Series Administration Manual page 290

12
STEP 6
234
Click Apply. The parameters are written to the Running Configuration file.
VLAN Translation
VLAN Translation includes the VLAN tunneling feature and the VLAN mapping one to one
feature.
VLAN tunneling is an enhancement of the QinQ/Nested VLAN/Customer mode VLAN
feature. It enables service providers to use a single VLAN to support customers who have
multiple VLANs, while preserving customer VLAN IDs and keeping traffic in different
customer VLANs segregated. This feature is known as "double tagging" or QinQ, because in
addition to the regular 802.1Q tag (Customer VLAN/C-VLAN), the switch adds a second ID
tag known as a Service Tag (S-VLAN), to forward traffic over the network. On an edge
interface, which is an interface where a customer network is connected to the provider edge
switch, C-VLANs are mapped to S-VLANs and the original C-VLAN tags are kept as part of
the payload. Untagged frames are dropped.
When a frame is sent on a non-edge tagged interface, it is encapsulated with another layer of
S-VLAN tag to which the original C-VLAN-ID is mapped. Therefore, packets transmitted on
non-edge interfaces frames are double-tagged, with an outer S-VLAN tag and inner C-VLAN
tag. The Service VLAN Tag is preserved while traffic is forwarded through the network
service provider's infrastructure. On an egress device, the S-VLAN tag is stripped when a
frame is sent out on an edge interface. Untagged frames are dropped.
The VLAN tunneling feature uses a different set of commands than the original QinQ/Nested
VLAN implementation, and adds the following functionality in addition to the original
implementation:
• Provides, per edge interface, multiple mappings of different C-VLANs to separate S-
VLANs
• Allows configuring a drop action for certain C-VLANs received on edge interfaces
• Allows configuring the action for C-VLANs not specifically mapped to an S-VLAN
(drop or map to certain S-VLANs)
• Allows configuring, globally and per NNI interface (network node interfaces –
backbone ports) the Ethertype of the S-VLAN tag. In the previous QinQ
implementation, only the Ethertype of 0x8100 was supported for a S-VLAN tag.
The S-VLAN specified by the user must be created on the device before configuring it on an
interface as an S-VLAN. If this VLAN does not exist, the command fails.
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4
VLAN Management
Regular VLANs