Design VLANs

[moses12315]

I know that seperate a LAN with VLANs it increase security but also the bandwidth of the lan links.

What is the max number of PCs that should be located to a LAN and despite the security but have only in mind the increase of the bandwidth of a LAN when we should seperate a LAN to VLANs.

For examble a LAN with 20 users is it wise to seperate to 2 VLANs.

Thanks

moses

[lgijssel · Accepted solution]

As a rule of thumb, it is advisable to maximize the number of hosts per vlan to about 100-150. The actual setup will largely depend on the applications that are used. If these are very bandwidth-hungry, you will need to reduce the amount of hosts per vlan.

Another issue is the amount of broadcast traffic on the network. (less = better)

regards,

Leo

[Joseph W. Doherty]

The primary purpose of VLANs is to support virtual segmentation.

Segmentation could be done for various reasons. One reason for physical segmentation was to increase bandwidth, especially when working with non-switched Ethernet.

However virtual segmentation may actually decrease effective bandwidth. The reason, tags are added to the frames on trunks. This is a very small loss and is accepted for the other positives segmentation can provide, such as security, as you mention, or host traffic containment (e.g. broadcasts), as Leo mentions.

You could increase bandwidth using VLANs if you dedicate uplink ports to them. However, if supported, some type of channeling is often better.