300 BigIron RX Series Configuration Guide53-1001810-01Configuring 802.1q-in-q tagging11As shown in Figure 25, the ports to customer interfaces are untagged, whereas the uplink ports tothe provider cloud are tagged, because multiple client VLANs share the uplink to the provider cloud.In this example, the device treats the customer’s private VLAN ID and 8100 tag type as normalpayload, and adds the 9100 tag type to the packet when the packet is sent to the uplink andforwarded along the provider cloud.As long as the switches in the provider’s network support the 9100 tag type, the data gets switchedalong the network. However, devices that do not support the 9100 tag type may not properlyhandle the packets.Figure 26 shows an example application of the 802.1Q-in-Q enhancement.FIGURE 26 802.1Q-in-Q configuration exampleIn Figure 26, the untagged ports (to customer interfaces) accept frames that have any 802.1Qtag other than the configured tag-type 9100. These packets are considered untagged on thisincoming port and are re-tagged when they are sent out of the uplink towards the provider. The802.1Q tag-type on the uplink port is 8100, so the device will switch the frames to the uplinkdevice with an additional 8100 tag, thereby supporting devices that only support this methodof VLAN tagging.Configuration rulesFollow the rules below when configuring 802.1q-in-q tagging:• Since the uplink (to the provider cloud) and the edge link (to the customer port) must havedifferent 802.1Q tags, make sure the uplink and edge link are in different port regions.• If you configure a port with an 802.1Q tag-type, the device automatically applies the 802.1Qtag-type to all ports within the same port region.• If you remove the 802.1Q tag-type from a port, the device automatically removes the 802.1Qtag-type from all ports within the same port region.• The device supports on configured tag-type per device, along with the default tag-type of 8100.For example, if you configure an 802.1Q tag of 9100 on ports 1 – 8, then later configure an802.1Q tag of 5100 on port 9, the device automatically applies the 5100 tag to all ports in thesame port region as port 9, and also changes the 802.1Q tag-type on ports 1 – 8 to 5100.Enabling 802.1Q-in-Q taggingTo enable the 802.1Q-in-Q feature, configure an 802.1Q tag type on the untagged edge links (thecustomer ports) to any value other than the 802.1Q tag for incoming traffic.To customer interface ProviderEdge Switch Uplink to provider cloudUntagged TaggedDA SA 8100 CustomerVLAN DA SA 8100 CustomerVLANProviderVLAN8100Configured tag-type 9100 Default tag-type 8100
