Ericsson ECN330, User Manual

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Configuring the ECN330-switch
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1553-KDU 137 365 Uen D 2006-06-16
6.12.1.12 Configuring IEEE 802.1Q Tunneling
IEEE 802.1Q Tunneling (QinQ) is designed for service providers carrying traffic
for multiple customers across their networks. QinQ tunneling is used to maintain
customer-specific VLAN and Layer 2 protocol configurations even when different
customers use the same internal VLAN IDs. This is accomplished by inserting
Service Provider VLAN (SPVLAN) tags into the customer’s frames when they
enter the service provider’s network, and then stripping the tags when the
frames leave the network.
A service provider’s customers may have specific requirements for their internal
VLAN IDs and number of VLANs supported. VLAN ranges required by different
customers in the same service-provider network might easily overlap, and traffic
passing through the infrastructure might be mixed. Assigning a unique range of
VLAN IDs to each customer would restrict customer configurations, require
intensive processing of VLAN mapping tables, and could easily exceed the
maximum VLAN limit of 4096.
QinQ tunneling uses a single Service Provider VLAN (SPVLAN) for customers
who have multiple VLANs. Customer VLAN IDs are preserved and traffic from
different customers is segregated within the service provider’s network even
when they use the same customer-specific VLAN IDs. QinQ tunneling expands
VLAN space by using a VLAN-in-VLAN hierarchy, preserving the customer’s
original tagged packets, and adding SPVLAN tags to each frame (also called
double tagging).
A port configured to support QinQ tunneling must be set to tunnel port mode.
The Service Provider VLAN (SPVLAN) ID for the specific customer must be
assigned to the QinQ tunnel port on the edge switch where the customer traffic
enters the service provider’s network. Each customer requires a separate
SPVLAN, but this VLAN supports all of the customer's internal VLANs. The
QinQ uplink port that passes traffic from the edge switch into the service
provider’s metro network must also be added to this SPVLAN. The uplink port
can be added to multiple SPVLANs to carry inbound traffic for different
customers onto the service provider’s network.
When a double-tagged packet enters another trunk port in an intermediate or
core switch in the service provider’s network, the outer tag is stripped for packet
processing. When the packet exits another trunk port on the same core switch,
the same SPVLAN tag is again added to the packet.