Building the network infrastructure in your data center

The network architect must help contribute to an energy-efficient and cost-effective data center network design -- without sacrificing performance. This can be accomplished by choosing optimal networking equipment. This tip will discuss some considerations for choosing energy- and space-saving routing and switching technology that can help cut power consumption and reduce your total number of switches.

Get the most out of your rack space
It almost goes without saying that using rack-mount equipment is essential if you want to maximize the floor space in your data center. Even racks have their limits, though. There is only so much rack space available, so it is important to make the most of it. This means selecting network hardware that will maximize your rack space.

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Find out how 'going green' can save you money
How green is my network? -- A look at the cost-savings benefit of green IT

Keeping it green: Design principles for efficient architectures

The green data center: Energy-efficient computing in the 21st century
No matter what you are shopping for, it is hard to ignore the "green" trend. Whether you are talking about networking hardware or something completely unrelated, all of the manufacturers seem to want to promote their products as being good for the environment.

As an IT professional, I'm not really all that concerned whether or not my network switches are green. That isn't to say that I don't care about the environment; I do. It's just that if I had to choose between energy efficiency and performance, I would choose performance every time. Even so, I believe that there is a way to have the best of both worlds and get energy efficiency, performance and a space-saving design all at the same time.

In my opinion, the best way to get a space-saving design and energy efficiency is to purchase network switches that have the highest number of ports possible. This approach makes sense from an environmental standpoint because each switch is going to have its own power supply built in. Generally speaking, one big switch is going to consume less electricity than two smaller switches, although there are exceptions. Fewer power supplies generally also mean that less heat is being produced. This in turn means that the air conditioners don't end up having to work as hard, which is also good for the environment.

Using switches with large numbers of ports typically ends up consuming less rack space than using a bunch of smaller switches. This can help you to get the most out of your available rack space.

Purchasing large switches: Some issues to consider
Purchasing a few large switches instead of a bunch of smaller ones generally makes sense. Even so, there are a few issues that you need to consider.

The first issue is price. It is sometimes less expensive to purchase several smaller switches than one big one. Sometimes the opposite is true, though. It just depends on what you are shopping for. If your budget is an issue, however, it pays to shop around.

The second issue with using large switches is that you are putting all of your eggs in one basket. In my experience, switch failures are rare, but they do happen. If an outage does occur, then the outage will affect more people if you are using larger switches. Whether you use switches with lots of ports or something a bit more modest, it is important to keep a spare switch on hand just in case a switch should fail.

The last issue that I want to talk about is switch throughput. Some lower-end switches do not offer enough total bandwidth to simultaneously service all of the switch's ports. As a general guideline, a switch's total bandwidth should be double the amount that each individual port is rated for, plus the amount of bandwidth that is dedicated to the uplink ports.

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Power and cooling considerations for data center network design

For example, suppose that you are considering purchasing a gigabit (Gb) switch with 24 ports. The first thing you should do is to make sure that each port can run at Gb speeds. I have seen some lower-end switches that claim to be Gb but that support Gb speeds on only a few ports. It is also important that the ports be auto-sensing and that they support lower speeds as well, because some network devices (such as printers) still use lower port speeds.

At any rate, although each of the ports is 1 Gb, the ports are all full duplex. This means that the ports can transmit and receive at the same time. On a 24-port switch, the total switch bandwidth would therefore need to be 48 Gb, not counting what the uplink ports are capable of delivering. Otherwise, network traffic will tend to get bogged down.

The uplink ports are also a very important consideration. The more ports you are using on a switch, the more uplink bandwidth you are going to need. Look for switches that offer dial uplink channels and that support 10 Gb uplink speeds. While you are at it, be sure to find out the total number of switches that can be linked together. It is important that the combined number of ports on each switch meet your current needs and allow plenty of room for growth.

About the author:
Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server and IIS. Brien has served as CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. As a freelance technical writer, he has written for Microsoft, CNET, ZDNet, TechTarget, MSD2D, Relevant Technologies and other technology companies. You can visit Brien's personal website at www.brienposey.com.

This was first published in February 2009

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