Mine Site Technologies impact, Руководство пользователя, Страница: 44 / 130

4.1 Understanding Trunk and Access Ports
VLANs can be assigned to trunk ports and access ports on a network. These two types of port allocations
determine how data is transmitted and relayed.
4.1.1 Trunk Ports
Trunk ports provide a connection between network switches and access points, and can be assigned to
multiple VLANs. They will only transmit frames (packets of data) that belong to the port's assigned
VLANs. To identify the frames, a network switch will add a tag to the frame (known as 802.1q trunking).
The tag contains the following information:
• VLAN ID — allows the network switch receiving a frame to identify the VLAN it belongs to.
• Priority ID — allows the network switch to prioritise distribution when multiple frames are being
transmitted. Priority ID ranges from 0-7, where 7 is the highest priority.
When a network switch receives a tagged frame, the tag is read to determine the VLAN it belongs to. The
tag is removed and distributed to devices connected on the same VLAN. If a tagged frame is sent to a
trunk port with a different VLAN ID not assigned to the port, it will be dropped.
When the network switch receives multiple frames, it will prioritise the distribution of frames based on
the Priority ID in the VLAN ID tag. For more information on configuring VLANs, see
Defining VLANs
on page 63.
4.1.2 Access Ports
Access ports connect client devices such as PCs and laptops to the network switch, and can only be
assigned to a single VLAN. Access ports can only send and receive untagged frames belonging to the
assigned VLAN. Any tagged frames sent to an access port will be dropped.
An example of VLAN traffic flow through trunk and access ports is shown in Figure 17: VLAN traffic
flow and described below.
Revision A 44 Wireless Network Switch User Manual
Understanding VLANs