More Details on the Duke 802.11n Deployment

After reading Cisco's press release and many of the news reports about Duke University's gigantic 802.11n deployment, I found many of my questions were left unanswered. So Cisco put me in touch with Duke's Kevin Miller, assistant director of Communications Infrastructure, whom I quickly peppered with some more questions about the deployment. Duke's 802.11n network, which will be a replacement for an existing 802.11a/b/g network, will also utilize both the 5GHz and 2.4GHz bands -- with both bands offering backward compatibility. For the 5GHz band, the university will utilize wide 40MHz channels while continuing to use 20MHz channels in the 2.4GHz band. To Miller's recollection, the 130M-bps wireless throughput rating that was initially reported for Duke's 802.11n network represented performance in the 5GHz band. I also asked Miller about his expectations for how the network will perform under load from a mix of 802.11n and legacy traffic, and he revealed some surprising findings about the client ratio they are currently seeing. "For some hard data, we are going to have to wait and see as the network rolls out. In our pilot area, we see very high use of 11g, but we also see, on average, about 40 percent of the clients are connecting via 802.11n. The Pilot area is a first-year residence hall and typically we see a lot of new hardware coming in with new students, and laptops manufactured for about a year now have had 11n capabilities," Miller said. He continued, "Really my next biggest investigation in going to be looking at the three generations we support -- 11b, 11g, 11n -- and trying to minimize the 11b clients first to protect the space a little more. To identify if and when there is an opportunity to discontinue supporting 11b. We know there are devices today that require supporting 11b, but they are dwindling over time." I also asked Miller about his team's -- and the university's -- plans for helping educate the students and users about the new network, and to help manage expectations for just what the network should be able to do. Miller said, "We are working closely with our computer store, as well as with administrators across campus, and making sure they understand not just the headline, but what are the impacts and what does it mean in terms of computer purchases and configurations." He continued, "We are working with departments and IT administrators throughout campus, and we are adding information to students' incoming packets. In April we send out packets of information to incoming students with a plethora of information about Duke -- not just our IT -- but everything about the university. Certainly one of the aspects in there will be the availability of the 11n network and what sort of things to look for when purchasing laptops." Miller said he also sees mobile devices with Wi-Fi inside to be of growing importance on the network, but laptops for now represent most of the wireless clients he is seeing. Lastly, we discussed Duke's plans for POE (power over Ethernet) support. These plans call for every access point to be powered via POE, a process that will require a gradual rollout of power in excess of that supported by the current 802.3af standard. Initially, Duke will target the highest priority areas and those areas with the greatest client density, then gradually upgrade support throughout the network.

After reading Cisco's press release and many of the news reports about Duke University's gigantic 802.11n deployment, I found many of my questions were left unanswered. So Cisco put me in touch with Duke's Kevin Miller, assistant director of Communications Infrastructure, whom I quickly peppered with some more questions about the deployment.

Duke's 802.11n network, which will be a replacement for an existing 802.11a/b/g network, will also utilize both the 5GHz and 2.4GHz bands -- with both bands offering backward compatibility. For the 5GHz band, the university will utilize wide 40MHz channels while continuing to use 20MHz channels in the 2.4GHz band.

To Miller's recollection, the 130M-bps wireless throughput rating that was initially reported for Duke's 802.11n network represented performance in the 5GHz band.

I also asked Miller about his expectations for how the network will perform under load from a mix of 802.11n and legacy traffic, and he revealed some surprising findings about the client ratio they are currently seeing.

"For some hard data, we are going to have to wait and see as the network rolls out. In our pilot area, we see very high use of 11g, but we also see, on average, about 40 percent of the clients are connecting via 802.11n. The Pilot area is a first-year residence hall and typically we see a lot of new hardware coming in with new students, and laptops manufactured for about a year now have had 11n capabilities," Miller said.

He continued, "Really my next biggest investigation in going to be looking at the three generations we support -- 11b, 11g, 11n -- and trying to minimize the 11b clients first to protect the space a little more. To identify if and when there is an opportunity to discontinue supporting 11b. We know there are devices today that require supporting 11b, but they are dwindling over time."

I also asked Miller about his team's -- and the university's -- plans for helping educate the students and users about the new network, and to help manage expectations for just what the network should be able to do.

Miller said, "We are working closely with our computer store, as well as with administrators across campus, and making sure they understand not just the headline, but what are the impacts and what does it mean in terms of computer purchases and configurations."

He continued, "We are working with departments and IT administrators throughout campus, and we are adding information to students' incoming packets. In April we send out packets of information to incoming students with a plethora of information about Duke -- not just our IT -- but everything about the university. Certainly one of the aspects in there will be the availability of the 11n network and what sort of things to look for when purchasing laptops."

Miller said he also sees mobile devices with Wi-Fi inside to be of growing importance on the network, but laptops for now represent most of the wireless clients he is seeing.

Lastly, we discussed Duke's plans for POE (power over Ethernet) support. These plans call for every access point to be powered via POE, a process that will require a gradual rollout of power in excess of that supported by the current 802.3af standard. Initially, Duke will target the highest priority areas and those areas with the greatest client density, then gradually upgrade support throughout the network.