Cisco Systems Inc. has announced another line of 802.11n wireless access points, saying that even if the IEEE hasn’t published the new specification, work done by the Wi-Fi Alliance constitutes a “de facto standard.”
The Aironet 1140 series incorporates new technology, called M-Drive, that makes managing the network easier and squeezes better performance out of legacy 802.11a, b and g client devices, according to Greg Beach, director of product management for Cisco’s wireless networking business unit.
The fixed form factor access points are available with single or dual radios, each capable of 300 Mbps throughput. They mount in the same brackets used for Cisco’s earlier generation wireless products and support power over Ethernet for easier deployment, Beach said.
“We really believe this is going to knock odown some barriers that our customers are facing today in deploying 11n,” he said.
The 1140 series will also ship in an “eco-box” – units of 10 APs that reduce packaging by 50 per cent, Beach said. “A lot of our customers have been asking for that sort of delivery vehicle,” Beach said.
The M-Drive technology involves both hardware and software, and is designed to make the network easier to manage, Beach said. For example, if an access point in the network goes down, other devices will increase their power; if there’s interference, the APs will switch to another channel.
‘True fairness’
ClientLink, one element of the M-Drive technology, is designed to extend the life of legacy 802.11a, b and g devices, and offer “true fairness” among clients on the network regardless of vintage, Beach said.
“It’s unlikely these devices are going to be forklifted out overnight,” Beach said. “These devices are going to be around in networks for quite some time.”
The root cause of inefficient connections, said Beach, is signal strength. Better signal strength means better throughput for legacy devices, he said.
Though the IEEE hasn’t released a specification for 802.11n – Draft 2.0 is due in January 2010 – adoption among Cisco’s customer base has been “phenomenal,” said Chris Kozup, senior manager of mobility solutions. Cisco’s Aironet 1250 series, launched a year ago, has sold 175,000 units. The Wi-Fi Alliance has certified 450 802.11n devices, and Intel has shipped 30 million wireless n clients.
“It’s important to note here the difference between the IEEE specification, which is a list of different specifications, and ultimately what gets delivered to the market through the Wi-Fi Alliance specification,” Kozup said. The Wi-Fi Alliance has created a de facto standard, he said, that’s “pervasive in the industry.”
One of the main drivers of 802.11n adoption is the average laptop refresh cycle, Beach said. With most companies on a three- to four-year refresh, new laptops are coming into the business, and they’re equipped with 802.11n. “11n is the easy choice. It’s the easy choice because it can unlock the potential that’s in the laptops, and because it’s completely backward-compatible with a, b and g technologies,” he said.
Also, customers are looking at how to manage bandwidth-intensive, real-time applications. 802.11n offers up to nine times the throughput over 802.11a or g; it’s also more reliable and handles latency-sensitive applications better, largely thanks to MIMO (multiple in, multiple out) signal processing and the fact that it uses two 20MHz channels. Packet aggregation – shipping multiple small packets together – reduces overhead.
John Yrigoyen, director of wireless solutions for NEC Unified Solutions Inc., said the backward compatibility of 802.11n is a major factor int adoption of the technology.
“A lot of our customers are still in that interim phase right now where they’re migrating their 802.11b clients to g, and with the new 1250s and 1140s it makes it easier for them to migrate those clients from 2.4 (GHz, the frequency of 802.11b devices) to 5 (GHz, 802.11g’s frequency), and then from 5GHz g to 5GHz n.”
Benefits don’t come cheap
According to an Info-Tech Research Group research note, while there are compelling arguments to upgrading to 802.11n, the benefits don’t come cheap. In practice, 802.11n networks will provide about eight times the throughput of 802.11g networks, and increase coverage by 50 per cent.
But to get real benefit from the network, all devices will have to be upgraded to 802.11n. Lower speed clients slow down the network as a whole, according to the research note. And the per-access-point cost of an 802.11n deployment could exceed $1,000.
The network would also have to be upgraded if it doesn’t have Gigabit Ethernet edge switches – and if the backbone isn’t Gigabit Ethernet, the whole infrastructure will have to be replaced, according to the paper.
