Пример конфигурации QinQ на Cisco Catalist 3560

ASCII Network diagram:

             +-------------------+
             | Customer Site     |
             |  switch (3560)    |
             +-------------------+
                Fa0/24 |
                       |  <------ dot1q trunk allowing only Vlan 310
                  Carrier WAN
                       |
                Fa0/1  |
             +-------------------+
             | Central PoP       |
             | Aggregation Switch|
             +-------------------+
          Fa0/24 |            | Fa0/2
                 |            |
                 |         +-------------------+
                 |         | Central PoP       |
                 |         | Network 2 Router  |
                 |         +-------------------+
                 |
             +-------------------+
             | Central PoP       |
             | Network 1 Router  |
             +-------------------+

------------------------------------------------------------

Customer site switch config (relevant bits):

ip vrf network2
!
vlan 310
 name CarrierUplink
!
vlan 500
 name Network2Uplink
!
interface GigabitEthernet0/1
 description Network 2 QinQ port (looped to Gig0/2)
 switchport access vlan 310
 switchport mode dot1q-tunnel
!
interface GigabitEthernet0/2
 description Network 2 Uplink (looped to Gig0/1)
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 500
 switchport mode trunk
!
interface GigabitEthernet0/24
 description Carrier Uplink
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 310
 switchport mode trunk
!
interface Vlan310
 description Network1 P2P
 ip address 172.30.1.2 255.255.255.252
!
interface Vlan500
 description Network2 P2P
 ip vrf forwarding network2
 ip address 172.40.1.2 255.255.255.252
!

------------------------------------------------------------
Central PoP Aggregation Switch config:

vlan 310
 name cust.site
!
interface FastEthernet0/1
 description link to Carrier
 switchport trunk encapsulation dot1q
 switchport mode trunk
!
interface FastEthernet0/2
 description link to Network2 Router
 switchport trunk encapsulation dot1q
 switchport mode trunk
!
interface FastEthernet0/48
 description link to Network1 Router
 switchport trunk encapsulation dot1q
 switchport mode trunk
!                                                                               

------------------------------------------------------------
Central PoP Network1 Router config:

vlan 310
 name cust.site
!
interface GigabitEthernet0/1
 description link to Aggregation Switch
 switchport trunk encapsulation dot1q
 switchport mode trunk
!
interface Vlan310
 description cust.site
 ip address 172.30.1.1 255.255.255.252                                          

------------------------------------------------------------
Central PoP Network2 Router config:

interface FastEthernet0/0
 description link to Aggregation Switch
 no ip address
 duplex auto
 speed auto
!
interface FastEthernet0/0.500
 encapsulation dot1Q 310 second-dot1q 500
 ip address 172.40.1.1 255.255.255.252
 ip ospf mtu-ignore                                                             

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https://puck.nether.net/pipermail/cisco-nsp/2011-January/076414.html