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C H A P T E R 2 | Using the Intel Express 460T Standalone Switch |
IEEE 802.1Q (Tag-Based) VLANs
The third type of VLAN supported by the 460T switch is based on the IEEE 802.1Q specification. The specification provides a uniform way to create VLANs within a network and enables you to create a VLAN that can also span across the network. Previously, VLAN implementation was vendor- specific so it was not possible to create a VLAN across devices from different vendors.
The 802.1Q VLAN works by using a tag added to the Ethernet frames. The tag contains a VLAN Identifier (VID) that identifies the frame as belonging to a specific VLAN. These tags allow switches that support the 802.1Q specification to segregate traffic between devices and communicate a device’s VLAN association across switches.
There are multiple advantages to implementing 802.1Q VLANs. First, it improves performance by helping to contain broadcast and multicast traffic across the switch. Second, ports can belong to more than one VLAN. Third, VLANs can span multiple switches that support the 802.1Q specification. Finally, it provides security and improves performance by logically isolating users and grouping them together. The 460T switch supports up to 256 tag- based VLANs.
Using the 460T
Intel Express 460T Standalone Switch
Module A
VLAN 1: | VLAN 2: |
Engineering | Manufacturing |
VLAN 1 computers |
|
can't see VLAN 2 | Server and printer |
computers | are members of both |
| VLANs |
A logical grouping can be mapped to a work group. For example, you can create a VLAN that groups all the users from the engineering department into one VLAN. This logical grouping improves performance by cutting down traffic that belongs to a different logical group (for example, marketing), improves security (engineering can’t see marketing), and eases moves because the user doesn’t have to be physically located in the same group to participate in the VLAN.
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