Features and benefits of the VLAN

Hello. I am doing some network research. I have some queries about network administration. I hope you can answer...

the following questions to clear my doubts.

These are my questions:
a) What are the key features of the VLAN?
b) What might be some benefits and limitations of the VLAN?
Thank you in advance for your time and consideration.

A VLAN is a single LAN that spans geographically dispersed locations, essentially making multiple LANs look like a single LAN. The benefits of a VLAN include the ability to share information and resources across the locations as if they were all under one roof. As a result of this, businesses can operate more efficiently with improved productivity. Site-to-site VPN is frequently used to implement VLAN with the added benefit of strong security. There are two fundamental limitations of VLANS: performance and management costs.

In regard to performance, local area networks typically operate at 100Mbps with latencies of less than 5ms. On the other hand, wide area networks typically connect at 1.5Mps or less with latencies averaging around 100ms. So, a VLAN will not perform as well as a local network. This is generally not a problem, but can be if applications are chatty (i.e., send a lot of small messages back and forth just to accomplish one task) or require a lot of bandwidth (e.g., video streaming). So, when designing a VLAN, one must take care to provision enough bandwidth to accommodate the applications being service.

In regard to management costs: A VLAN is a wide area network and typically requires additional security such as that provided by IPSec and PKI. The need to support geographically dispersed locations and extra security can increase overhead. Basically, it's much more complex than connecting computers together in the same building as would be the case with an ordinary LAN.

This was last published in August 2002

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