2005/08/07 What is a Managed Switch?

A managed switch allows you to control the individual ports of your switch. Features of course vary with manufacturers and models, but even the most basic will have the ability to turn the port on or off and control its link speed and duplex settings. That control is for security; it prevents someone just walking in and connecting to your lan through an unused port.

Beyond that, you might be able to specify a particular MAC address that is allowed to connect. That prevents someone from replacing machines with their own. You might be able to set login authentication, also. You may be able to designate certain ports as "high priority"; for example the ports your servers are on. Setting bandwidth limits, monitoring port traffic and of course logging are also features.

VLANS (Virtual LANS) are a popular option. This allows you to set a broadcast domain on certain ports, so that broadcast traffic isn't passed on to the other ports. This can also isolate machines from each other for security purposes.

Link aggregation ties together multiple ports, allowing two switches to be connected more than once for higher throughput between them. The switch may support Spanning Tree, which lets you have multiple paths for redundancy without having to worry about looping.

These switches may also have snmp agents that will report status to snmp monitors. Nowadays they usually have a web interface for configuration in addition to the traditional command line method. Older models might require access through a serial console, but more recent devices will have the web interface.

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Comments




Fri Jan 23 09:20:57 2009: Subject:   amith


This artical is very good.. I want to know how spanning tree is used in managed switches? Can anyone answer.. please..





Fri Jan 23 12:37:06 2009: Subject:   TonyLawrence


That could be an article by itself. Spanning tree simply prevents loops when you have multiple switches wired together in a way that otherwise could loop back. Do a Google search if you want to find articles that explain how it works in practice,

This site deals with small business - I seldom am working with anyone large enough to even need such things; many of my customers get by with a single switch :-)

Still, these kind of features are appearing in lower priced equipment.. I imagine it might eventually show up in the $50 units my customers are more likely to own.

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