This article provides information about Q-in-Q (dot1q tunnel). It is used to tag traffic, from multiple customers, aggregating on a single interface into separate SVLANs.

• Using the 802.1Q tunneling feature, service providers can tag two or more customer’s traffic (with separate VLAN tags) into different SVLAN tags, when all the customer traffic is received on a single interface.
• In Q-in-Q tunneling, as a packet travels from a customer VLAN (CVLAN) into a service provider's VLAN (SVLAN), a customer-specific 802.1Q outer tag is added to packets.
• This additional tag is used to segregate traffic into service–provider–defined service VLANs.
• The original customer 802.1Q tag of the packet remains intact and is transmitted transparently, passing through the service provider's network.
• The SVLAN tag is added on egress for incoming packets; here you can create a separate group for each customer tagged with a specific SVLAN.
• As the packet leaves the SVLAN in the downstream direction, the provider 802.1Q tag is removed; leaving the original customer tag on the packet.

Topology:

• Customer 1 and Customer 2 traffic is aggregated on the CPE1 and the Service Provider PE1 is receiving both customers’ traffic on the single interface ge-0/0/2.
• Customer 1 traffic with VLAN tags 10 & 20 will be double tagged using SVLAN 3001 and customer2 traffic with VLAN tags 30 & 40 will be double tagged with SVLAN 3002.
• PE2 and PE3 will remove the respective SVLAN tags before sending the traffic to the respective customers.

set interfaces ge-0/0/0 unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/0 unit 0 family ethernet-switching vlan members all

set interfaces ge-0/0/0 unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/0 unit 0 family ethernet-switching vlan members all
set interfaces ge-0/0/1 unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan members all
set interfaces ge-0/0/2 unit 0 family ethernet-switching

set vlans svlan1 vlan-id 3001
set vlans svlan1 interface ge-0/0/2.0
set vlans svlan1 dot1q-tunneling customer-vlans 10
set vlans svlan1 dot1q-tunneling customer-vlans 20
set vlans svlan2 vlan-id 3002
set vlans svlan2 interface ge-0/0/2.0
set vlans svlan2 dot1q-tunneling customer-vlans 30
set vlans svlan2 dot1q-tunneling customer-vlans 40

set ethernet-switching-options dot1q-tunneling ether-type 0x8100

set interfaces ge-0/0/0 unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/0 unit 0 family ethernet-switching vlan members all
set interfaces ge-0/0/1 unit 0 family ethernet-switching

set vlans svlan1 vlan-id 3001
set vlans svlan1 interface ge-0/0/1.0
set vlans svlan1 dot1q-tunneling customer-vlans 10
set vlans svlan1 dot1q-tunneling customer-vlans 20

set ethernet-switching-options dot1q-tunneling ether-type 0x8100

root@3200-5# run show vlans dot1q-tunneling extensive 
VLAN: svlan2, Created at: Sun Jan  3 20:46:17 2010
802.1Q Tag: 3002, Internal index: 4, Admin State: Enabled, Origin: Static
Dot1q Tunneling status: Enabled
Customer VLAN ranges:
      30-30
      40-40
Protocol: Port Mode, Mac aging time: 300 seconds
Number of interfaces: Tagged 1 (Active = 1), Untagged  1 (Active = 1)
      ge-0/0/0.0*, tagged, trunk
      ge-0/0/1.0*, untagged, access

set interfaces vlan unit 10 family inet address 10.10.10.19/24
set interfaces vlan unit 30 family inet address 30.30.30.19/24

set interfaces vlan unit 10 family inet address 10.10.10.17/24

set interfaces vlan unit 30 family inet address 30.30.30.4/24

root# ping 10.10.10.17
64 bytes from 10.10.10.17: icmp_seq=0 ttl=53 time=2.785 ms
64 bytes from 10.10.10.17: icmp_seq=0 ttl=53 time=1.705 ms

root# ping 30.30.30.4
64 bytes from 30.30.30.4: icmp_seq=0 ttl=53 time=2.785 ms
64 bytes from 30.30.30.4: icmp_seq=0 ttl=53 time=1.115 ms

• Understanding Q-in-Q Tunneling on EX-series Switches