NetComm IP DSLAM NCT480 - Manual (Page 82)

NCT480 IP DSLAM User Guide YML856 Rev3
8 www.netcomm.com.au
vLAN Mode Setting
With the Ethernet becoming cheaper and more popular, the Ethernet networks are expanding to cover metros.
This is leading to deployment of MEN (Metropolitan Ethernet network). The existing support for VLAN as
standardized in IEEE 802.1Q is not able to scale to MEN deployment, because of limited 4095 VLANs and
hence the requirement for VLAN Stacking.
VLAN Stacking, also known as Q in Q, is the mechanism where one VLAN (Virtual Local Area Network) may be
encapsulated within another VLAN. This allows a carrier to partition the network among several national ISPs,
while allowing each ISP to still utilize VLANs to their full extent. It is very important to logically separate all
traffic between ISPs – for security, for offering different levels of service to prospective ISP customers and the
ability to utilize full VLAN space.
In a typical network scenario Columbia is on edge of provider network (Ethernet Aggregation Network), the
location of DSLAM as shown in Figure 6-4 depicting Network Scenario.
Figure 6-4 Network Scenario