SGS-6341-Series User Manual

Chapter 25 Flexible Q-in-Q
Configuration
25.1 Introduction to Flexible Q-in-Q
25.1.1 Q-in-Q Technique
Dot1q-tunnel is also called Q-in-Q (802.1Q-in-802.1Q), which is an expansion of 802.1Q. Its
dominating idea is encapsulating the customer VLAN tag (CVLAN tag) to the service provider
VLAN tag (SPVLAN tag). The packet with two VLAN tags is transmitted through the backbone
network of the ISP internet to provide a simple Layer 2 tunnel for the users. It is simple and
easy to manage, applicable only by static configuration, and especially adaptive to small office
network or small metropolitan area network using Layer 3 switch as backbone equipment.
There are two kinds of Q-in-Q: basic Q-in-Q and flexible Q-in-Q, the priority of flexible Q-in-Q is
higher than basic Q-in-Q.
25.1.2 Basic Q-in-Q
Basic Q-in-Q based port. After a port configures Q-in-Q, whether the received packet with tag
or not, the device still packs the default VLAN tag for the packet. Using basic Q-in-Q is simple,
but the setting method of VLAN tag is inflexible.
25.1.3 Flexible Q-in-Q
Flexible Q-in-Q based data flow. It selects whether pack the external tag and packs what kind
of the external tag by matching the material flow. For example, implement the property of
flexible Q-in-Q according to the user’s VLAN tag, MAC address, IPv4/IPv6 address, IPv4/IPv6
protocol and the port ID of the application, etc. So, it can encapsulate the external tag for the
packet and implements different scheme by different users or methods.
25.1.4 Flexible Q-in-Q Configuration Task List
The match of flexible Q-in-Q data flow uses policy-map rule of QoS to be sent; the
configuration task list is as follows:
1. Create class-map to classify different data flows
2. Create flexible Q-in-Q policy-map to relate with the class-map and set the corresponding
operation
3. Bind flexible Q-in-Q policy-map to port
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User’s Manual of SGS-6341 series