Education networks yesterday experienced massive spikes in wireless LAN and Internet traffic as thousands of students toting iPhones and iPads tried to download iOS 7, which became available at 1 p.m. EDT.
How massive? At one basketball-mad southern university, the iOS update traffic surpassed the previous record peak: the NCAA college basketball tourney. “We were surprised,” said a senior network engineer there, speaking on condition of anonymity.
Some locations were seeing WLAN traffic surge five times above normal levels. Internet traffic over the WAN pipe often doubled. Some IT professionals say they saw a high-level of failed update attempts, leading students to re-attempt the download right away. A tweet by one student complained that his university’s Internet connection was like a dialup link.
Despite the surge, network disruptions seemed rare. The main problem in some locations was that the Internet connection bogged down. Many of these locations were caching the iOS update, often via a cloud-based service such as Akami. The caching server then provided the update to all subsequent users, without new roundtrips to the Internet and their attendant bandwidth tax.
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“Our Internet pipe has been pegged for the last four hours,” says Arthur Brant, director of networking service at Abilene Christian University in Texas. “This congestion manifests in slow webpage loads and slow download times for the iOS7 update. I've also seen a couple of tweets from students who have expressed frustration with ACU's 'slow' Internet service. One student's tweet compared that Internet speed to dial-up service."
One college saw Internet bandwidth more than double, from just under 300M to a peak of 850Mbps, with most use clustering in the 600M to 800Mbps from 1 p.m. to 3 p.m. Another reported that its border firewall maxed out several times during the day. In another network, total inbound traffic over the WLAN was hovering around 1.2G to 1.4Gbps when it leaped to over 2Gbps almost as soon as iOS 7 became available. Total inbound Internet traffic saw a corresponding leap: from around 2G to 3G to just over 4Gbps.
Another tool being used to manage the bandwidth crunch was traffic shaping software from companies such as iBoss. The software identifies traffic based on predefined categories and dynamically prioritizes and throttles different categories at peak moments.
The Denver Public Schools (DPS) system uses four of the iBoss Enterprise Secure Web Gateways, with web filtering and bandwidth management modules.
“The rule I created looks for the domain ‘akamaitechnologies.com’ or the IP subnet 126.96.36.199/24 (what appears to be our Internet provider's Akamai caching servers) and puts a hard max bandwidth limit of 600,000 kbps on downstream (incoming) traffic,” says Josh Robertson, a senior wireless engineer and infosecurity admin for DPS’ department of technology services.
“For the users of our Internet connection this keeps Akamai traffic (Apple uses Akamai for caching) to 60 percent of our total bandwidth,” he says. “So while this will slow down iOS upgrades when they're using more than 600 megabits of bandwidth, it ensures that 40 percent of our total bandwidth is available for other applications.”
DPS’ Internet pipe was fast approaching capacity at 1 p.m., but after Robertson applied the brakes, “it started dropping and had capacity available for other applications again.”