合勤交换机802.1qvlan划分[整理].pdf

A VLAN (Virtual Local Area Network) allows a physical network to be

partitioned into multiple logical networks. Stations on a logical network belong

to one group called VLAN Group. A station can belong to more than one group.

The stations in the same VLAN group can communicate with each other. With

VLAN, a station cannot directly talk to or hear from stations that are not in the

same VLAN group(s); the traffic must first go through a router.

In MTU or IP-DSLAM applications, VLAN is vital for providing isolation and

security among the subscribers. When properly configured, VLAN prevents

one subscriber from accessing the network resources of another one on the

same LAN. Therefore, a user will not see the printers and hard disks of another

There are two most popular VLAN implementations, Port-based VLAN and

IEEE 802.1q Tagged VLAN. ZyXEL Managed Switch supports both VLAN

implementations. The biggest difference between both VLAN implementations

What is IEEE 802.1Q Tag-based VLAN?

Regarding the IEEE 802.1Q standard, Tag-based VLAN uses an extra tag in

the MAC header to identify the VLAN membership of a frame going across the

bridges. This tag is used for VLAN and QoS (Quality of Service) priority

identification. The VLANs can be created statically by hand or dynamically

only the priority level is significant and the default VID of the ingress port is

given as the VID of the frame.

I. Ingress Process:

Each port is capable of passing tagged or untagged frames.

incoming tagged and untagged frames: