Green networking Part 2: Networks in need of a green thumb

This Q&A discusses the networking devices that are the biggest power drain and the best time to consider networking solutions that are a bit more green.

PREVIOUSLY: Convincing executives to go green

Network power consumption comes in many forms. In part two of this Q&A, Gary Audin, president of network consulting firm Delphi, discusses the networking devices that are the biggest power drain and the best time to consider networking solutions that are a bit more green.

What's the big power consumer when you look at the LAN closet? What's gobbling up the most power?

Gary Audin: It's the LAN switch, because a LAN switch has more physical adapters than a router does. A router's big if it has a dozen interface cards on it. Most routers have two, six or eight, something like that. But a LAN switch has 48, 96 or maybe even 128 ports on it ... so the physical number of interface cards and driving those interface cards, forget about Power over Ethernet (PoE), it's simply a lot bigger because there are so many cards.

The second thing is that you don't see PoE coming from a router to drive the networks it is connected to. That's the job of the LAN switch. So that further increases the power consumption of the LAN switch.

The third part is: What do you think is the component that's most likely to fail in a LAN switch? What would you back up first? The power. So you put in dual power supplies. Now, when you put in dual power supplies, you turn them both on so that if one fails, there's no interruption to service. That means the second power supply is also generating heat and consuming power just for the possibility that it will be the backup. That may as much as double the power consumption of the LAN switch. You want them to be full power, you don't want interruption, and you don't want a switchover, because if we didn't make them full power there would be a start-up time for the LAN switch. If it lost power, it would have to come back up again. It would have to reconfigure itself. It has to do spanning tree or whatever it has to go through so that there's recovery time for the LAN switch. Avoiding that means putting in dual power supplies, both running simultaneously.

As we think about PoE, we think about keeping the phones running. So we're going to put in battery systems to drive those LAN switches when power goes out. When you go through a battery system, you use more energy than you would provide just by turning it from AC to DC back into AC. There's an inefficiency there that goes on top of the LAN switches. It's not as bad as having backup dual-power supplies, but there's another cost of energy there just to keep the battery systems running.

Say company X, maybe it has, maybe it hasn't taken any steps toward power consumption...

Audin: ... They're coming up for replacement. Their switches are getting old, three to four years old, and they're considering new switches.

Say they're at a point in time when they're not in a refresh cycle and are not yet considering new switches. Maybe they're only a year and a half or two years in, and someone says, "We're consuming a heck of a lot of power and we need to cut it down." What can they do aside from buying new switches? What steps can they take that aren't as drastic as putting in new LAN switches?

Audin: There are products now that are power managers that shut down devices as their power consumption goes down, saying this device is in standby and a switch will turn it off until something is needed -- auxiliary power management devices. Why does everything have to be turned on all the time? It would have to be external. Whatever fix we do has to be external to the LAN switch. If I don't need this all the time, can I have a device behind the consumer of power that will shut down the use of that power for a certain period of time?

One of the other issues is whether the building designers set up the air conditioning for all of this IT stuff on a separate grid. We can shut down power and a lot of the building's consumption and keep up the IT stuff and isolate it. If I don't do that, I may have to keep some building power up to keep the IT closets up, and the building power is a waste. When you're doing greenfield or you're refurbishing a whole building, you have to reconsider how you air condition and power all of the rooms and closets from IT versus the rest of the building.

What networking vendors right now have a proactive approach, cutting down on energy consumption and going green?

Audin: There's a whole bunch of vendors, mostly in the chip area, that are looking at that. And they realize that as chips have become faster, they use more electrical power and produce more heat, even though they're physically smaller. So the chip manufacturers are looking at how they can produce chips that require less energy.

But that goes into the network interface cards. There's a committee either formed or being formed to try and make Ethernet green, but the results of that work are not expected to come out until 2010 or 2012. But think about how many NIC cards there are in the world. What if we could reduce their power consumption by 15%? That would be a significant amount of power. One of the problems is not so much that an individual item uses a lot of power; it's the fact that a company buys so many of them. You don't buy a router; you don't buy a LAN switch. You buy many of them -- sometimes hundreds or thousands. So, cumulatively, they add up to a considerable amount of consumption, but individually they don't seem to be doing much to the environment at all.

If these chipmakers start manufacturing chips that consume less power, that trickles down to the vendor, eventually making its way into the LAN closets in the enterprise, who's going to be paying for the added costs of the chipmakers' running tests? Is it going to cost more for the average enterprise to deploy networking gear that consumes less power as opposed to the status quo?

Audin: How long do enterprises keep a LAN switch or router? Four to five years? So, in one sense, there's going to be a turnover or churn of this equipment. Period .... Therefore, if a customer is going to buy this stuff and replace it every three to five years, during the next round, they should put in power consumption requirements. The point is they're going to be buying new stuff anyway. They have VLANs and QoS and a whole bunch of other things to get in there as well, but they have to put power consumption and air conditioning requirements into the decision matrix. It's possible the stuff may cost a little bit more, but their energy will cost a lot less in the long run. So when they look at the total cost of ownership of buying a product and managing its power consumption, they should end up with a positive number, saying the total cost of ownership will be lower once they include all of the energy costs.

Is that a shift that you have noticed only recently?

Audin: Vendors, especially those of chips and switches, have been talking about this for a few years, but it's finally coming to the point where we're getting products out there that take advantage of power-consumption technologies.

How many phones do you think are out there that Cisco has sold? Millions of them. If those millions of phones are Class 2, they consume under 7W; if they're Class 3, it's well over 7W. The VoIP phone is pushing this to a point where to run VoIP phones there's a lot more power consumption than the traditional TDM stuff.

How much power did TDM phones consume?

Audin: Probably a watt or two per phone. And there are Class 2 phones now, some of which are around 2W or 3W, others that are 6W or 7W. Within the Class 2 variety, there are phones that consume half as much power as other phones that are also Class 2. And further, if you look at colored screens and you look at Gigabit phones, those traditionally are Class 3 -- the Class 3s run between 7W and 13W. You look at these phones and you have colored screens and can do video and have other stuff built in -- I need power to run that. As we look at more and more advanced features and the ability to do unified communications on my IP phone rather than the soft phone, I now have a real problem because I have to ask myself whether I can afford the higher power or whether I should look at someone else's product (for a phone with color and everything else) that's lower power, because there are going to be so many of these phones [deployed].

How does that come into play, especially when the people buying and installing the phones don't know the amount of power that's being consumed?

Audin: Much of the buyer side of this industry is unaware. The goal is to develop more awareness about this. Make this one of your criteria. It's a criterion that has not been there in 34 years of IT.


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