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Troubleshooting Q&A - January 6, 2006

Managing With Unmanaged Switches

While it's true that managed switches are technically superior to unmanaged switches, that superiority comes with more complexity and the need for a network engineer to get the best performance. For those reasons, unmanaged switches are best for small networks.

By Ron Pacchiano

Q.   I maintain the computer network for a small community center in Florida. The network is composed of three Windows 2000 servers and about 20 Windows XP Professional workstations. Over the next year, we're expecting to add at least another 10 workstations to the network. We also have a couple of access points installed for members with wireless laptops and about a half dozen network printers. As a result, our current switch no longer has the capacity we need to connect all of the devices we're anticipating. So I either need to add an additional switch in order to increase our current port capacity or I need to replace the current switch with a larger one.

While researching new switches, I noticed that some of the ones I was coming across were being referred to as managed switches. I'm not familiar with these and always thought that a switch was for the most part the same as any other switch (expect for maybe brand loyalty). However, I noticed that these "managed switches" were typically much more expensive then the nonmanaged ones. They also had a number of features listed in there specifications that I didn't understand. So now I'm confused and not sure how to proceed. What is the difference between managed and unmanaged switches and would you recommend I get one for our environment? Thanks for your help

A.   If your background is in small LAN environments (like your community center) I can understand how the discovery of managed switches might be confusing. As you observed, managed switches are usually much more expensive then their nonmanaged counterparts and, as consumers, the first thing we thing of is that if it's more expensive, then it's got to be better. The problem with this logic though is that "better" can sometimes be a subjective term.

Speaking from a strictly technological point of view, managed switches are far superior to nonmanaged switches, but that superiority comes at a price. More features equate to more complexity and often require a skilled network engineer to get the best performance out of them. Due to these factors, you rarely find managed switches outside of medium- to large-sized organizations.

So before we go any further, I can tell you right now that you don't need to invest in managed switch for your network at the community center. While there are numerous benefits to using them, they are quite frankly overkill for the size environment you have. A simple, inexpensive unmanaged switch is all you need. Whether to expand your current one or purchase a larger one is a judgment call I'll leave to you. Now with that out of the way, let me see if I can explain the differences between a managed an unmanaged switch in a bit more detail for you.

The simplest way to think about it is this: A managed switch lets you take control of your network and all the traffic moving through it, while an unmanaged switch simply allows Ethernet devices to communicate with one another. For example, when you connect your Ethernet devices (PC, network printer and so on) to an unmanaged switch, they usually will communicate with each other automatically. They use a protocol called "auto-negotiation" to agree upon certain communication parameters. One parameter they negotiate is the data rate — generally 10, 100 or 1000MBps. Another is whether to use half-dupl;ex or full-duplex mode.

Full-duplex allows communications to exist in both directions at the same time, while half-duplex allows for only one way communication at a time. Other parameters include flow-control, for controlling the rate at which data is received so that frames can be processed and Auto-MDIX, which decides which wire pair will be used for transmitting and receiving data. You can monitor this using the simple status LEDs on the switch, which give you some feedback regarding link status and activity. Since so much happens behind the scenes, there really isn't much for you to do.

A managed switch, on the other hand, does all of this as well, but provides you with the flexibility of being able to adjust the communication parameters of each port on the switch to any setting you desire. This gives you the option of monitoring and configuring your network in a variety of different ways, as well as provides you with greater control over how data travels over the network and who has access to it.

Through the use of SNMP (Simple Network Management Protocol) you can view a multitude of network statistics. This includes the number of bytes and/or frames transmitted and received, errors generated and port status. Statistics for each can be viewed for each individual port in the switch. Some managed switches make this data available via a Web server so that you can access this information with a standard Web browser. Others use dedicated or even proprietary software for this. Most managed switches also offer advanced features that help to enhance your control over the network. Here is a chart that showcases some of the more common features available on most managed switches:

Features Benefits
Virtual Local Area Network (VLAN)
  • Isolate traffic between groups of ports
  • Control access to the various VLAN groups
  • Allow devices that need to communicate to each other the maximum bandwidth
  • Bandwidth Rate Limiting
  • Set a maximum bandwidth for each port
  • Prevent unnecessary communication traffic from overwhelming devices
  • Quality of Service (QoS)
  • Allow "high priority" messages quick throughput
  • Define message importance
  • Simple Network Management Protocol (SNMP)
  • Monitor switch port parameters
  • Allows easy access to switch information for HMI, SCADA and other applications
  • Port Mirroring
  • Provides message troubleshooting access
  • Allows messages to be monitored for message content
  • Trunking redundancy
  • Relay contacts, flashing LEDs and SNMP traps help to quickly identify the broken links.
  • Trunking also provides more bandwidth between switches
  • The bottom line is this: If you're connecting a very large network, which is distributed over a large area, then managed switches that can provide more diagnostic information about the status of each connection could prove to be more useful. If, however, you're connecting a network that is limited to a small number of systems on local LAN, then a managed switch may add a lot of unnecessary complexity and expense to the equation that you don't need.

    I hope this helps clear things up for you, but if you would like to learn more about managed switches and how they work, then I'd suggest you visit this site. It has some helpful animated tutorials that might make some of these esoteric concepts a bit easier to understand. Best of luck!

    Use our feedback form to submit your questions on home or SOHO networking issues. Please be as specific as possible. We cannot guarantee to answer every question we get, but we’ll consider them all.



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