SNR S2940-8G-v2, Руководство по настройке

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SNR S2940-8G-v2 Switch Configuration Guide
Dot1q-tunnel Configuration
Chapter 17
Dot1q-tunnel Configuration
17.1 Introduction to Dot1q-tunnel
Dot1q-tunnel is also called QinQ (802.1Q-in-802.1Q), which is an expansion of 802.1Q. Its dom-
inating idea is encapsulating the customer VLAN tag (CVLAN tag) to the service provider VLAN
tag (SPVLAN tag). Carrying the two VLAN tags the packet is transmitted through the backbone
network of the ISP internet, so 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 scale metropolitan area network using layer-3 switch as backbone equipment.
Customer
networks 2
Customer
networks 1
Trunk
Trunk
ISP Network
CE1
CE2
PE1
P
PE2
This port on PE2 is enabled
QinQ and belong to VLAN 3
This port on PE2 is enabled
QinQ and belong to VLAN 3
On the customer port
Trunk VLAN 200-300
On the customer port
Trunk VLAN 200-300
Figure 17.1: Dot1q-tunnel based Internetworking mode
As shown in above, after being enabled on the user port, dot1q-tunnel assigns each user
an SPVLAN identification (SPVID). Here the identification of user is 3. Same SPVID should be
assigned for the same network user on different PEs. When packet reaches PE1 from CE1,
it carries the VLAN tag 200-300 of the user internal network. Since the dot1q-tunnel function
is enabled, the user port on PE1 will add on the packet another VLAN tag, of which the ID is
the SPVID assigned to the user. Afterwards, the packet will only be transmitted in VLAN3 when
traveling in the ISP internet network while carrying two VLAN tags (the inner tag is added when
entering PE1, and the outer is SPVID), whereas the VLAN information of the user network is open
to the provider network. When the packet reaches PE2 and before being forwarded to CE2 from
the client port on PE2, the outer VLAN tag is removed, then the packet CE2 receives is absolutely
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