User Services on a Metro Ethernet

On the network shown in Figure 1, DSLAMs support multiple permanent virtual channel (PVC) access. A user uses multiple services, such as HSI, IPTV and VoIP.

Figure 1 QinQ on a Metro Ethernet

PVCs are used to carry services that are assigned with different VLAN ID ranges. The following table lists the VLAN ID ranges for each service.

Table 1 Mapping between services and VLAN IDs

Service Name

Full Name



high-speed Internet

101 to 300


Voice over Internet Protocol

301 to 500


Internet Protocol Television

501 to 700

If a user needs to use the VoIP service, user VoIP packets are sent to a DSLAM over a specified PVC and assigned with VLAN ID 301. When the packets reach the UPE, an outer VLAN ID (for example, 2000) is added to the packets. The inner VLAN ID (301) represents the user, and the outer VLAN ID (2000) represents the VoIP service (the DSLAM location can also be marked if you add different VLAN tags to packets received by different DSLAMs). The UPE then sends the VoIP packets to the NPE where the double VLAN tags are terminated. Then, the NPE sends the packets to an IP core network or a VPN.

HSI and IPTV services are processed in the same way. The difference is that QinQ termination of HSI services is implemented on the BRAS.

The NPE can generate a Dynamic Host Configuration Protocol (DHCP) binding table to avoid network attacks. In addition, the NPE can implement DHCP authentication based on the two-layer tags and has Virtual Router Redundancy Protocol (VRRP) enabled to ensure service reliable access.

Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
Next topic >