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Aug 28, 2009

TYPES OF VLANS VIRTUAL LOCAL AREA NETWORKS

There are a number of different strategies for creating Virtual Local Area Networks, each with their own approaches to defining a station’s membership in a particular VLAN.

1. Port Based Vlans

A port based VLAN switch determines the membership of a data frame by examining the configuration of the port that received the transmission or reading a portion of the data frame’s tag header. A four-byte field in the header is used to identify the VLAN. This VLAN identification indicates what VLAN the frame belongs to. If the frame has no tag header, the switch checks the VLAN setting of the port that received the frame. If the switch has been configured for port based VLAN support, it assigns the port’s VLAN identification to the new frame.

2. Secure Fast Vlans

Cabletron Systems’ SECURE FAST VLAN strategy takes a different approach to creating virtual LANs. In a SECURE FAST VLAN environment, the switches in the network recognize Network Layer routing requests and translate them. Based on this translation, the switches set up a connection between the end devices in the network.

3 Other Vlan Strategies

VLANs may also be created by a variety of addressing schemes, including the recognition of groups of MAC addresses or types of traffic. One of the best-known VLAN-like schemes is the use of IP Subnets to divide networks into smaller subnetworks. These other VLAN types offer performance advantages and disadvantages that can be quite different from those available with the port based VLAN strategy.

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