FoxGate S6424-S2C2 series User Manual

QinQ Configuration
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Chapter 37. QinQ Configuration
37.1 Introduction to QinQ
37.1.1 Understanding QinQ
In the VLAN tag field defined in IEEE 802.1Q, only 12 bits are used for VLAN IDs, so a
switch can support a maximum of 4,094 VLANs. In actual applications, however, a large
number of VLANs are required to isolate users, especially in metropolitan area networks
(MANs), and 4,094 VLANs are far from satisfying such requirements. shows the structure of
802.1Q-tagged and double-tagged Ethernet frames. The QinQ feature enables a device to
support up to 4,094 x 4,094 VLANs to satisfy the requirement for the amount of VLANs in the
MAN.
Figure 37-1 QinQ Ethernet frame structure
The port QinQ feature is a flexible, easy-to-implement Layer 2 VPN technique, which
enables the access point to encapsulate an outer VLAN tag in Ethernet frames from customer
networks (private networks), so that the Ethernet frames will travel across the service
provider’s backbone network (public network) with double VLAN tags. The inner VLAN tag is
the customer network VLAN tag while the outer one is the VLAN tag assigned by the service
provider to the customer. In the public network, frames are forwarded based on the outer
VLAN tag only, with the source MAC address learned as a MAC address table entry for the
VLAN indicated by the outer tag, while the customer network VLAN tag is transmitted as part
of the data in the frames.

FoxGate S6424-S2C2 series Specifications

General

Brand	FoxGate
Model	S6424-S2C2 series
Category	Switch
Language	English