Software-based iPad Wi-Fi problems detailed by Princeton

Posted:
in Current Mac Hardware edited January 2014
A software glitch in Apple's iPad causes the device to continue using a network-assigned IP address after its lease has expired, according to data collected by Princeton University.



The Internet Protocol (IP) address of a device is a unique identifier that allows communication between devices. An IP address is assigned through a method known as Dynamic Host Configuration Protocol (DHCP), and these addresses can dynamically change over time on a private network as devices disconnect and reconnect.



A DHCP client, such as an iPad, will "lease" a unique IP address to a device on a network for a set period of time. Once that time has elapsed, the DHCP client asks the server to renew that lease. Apple's iPad, however, does not go through that renewal, according to information from the Office of Information Technology at Princeton University.



Instead, the office has found that the iPad will incorrectly continue using an IP address without renewing the lease, usually for hours. The issue is resolved when the iPad asks for a new DHCP lease, or the iPad disconnects from the network.



The information suggests it is a software issue within iPhone OS 3.2, and is likely something that Apple could repair through an update to its mobile operating system.



The problem was found to be common on Princeton's campus, with more than half -- 25 of 41 -- of all iPads demonstrating the malfunction as of April 18. If that ratio bears out on a larger scale, there are likely a huge number of iPad owners experiencing similar issues, as Apple sold more than 500,000 devices in its first week.



The report noted that some devices have demonstrated the malfunction several times, and eight devices were outright blocked from the university's network.



"When a DHCP client malfunctions this way repeatedly, Princeton blocks the device from using those campus network services which rely on the device's DHCP client respecting lease times," the IT office said. "These include our wireless services. We do this to protect other customers of those services from the disruptions caused by the malfunctioning devices."



The school has published a temporary workaround for the issue, but is working with Apple and providing them with technical data in hopes of solving the problem. That data was sent to Apple on April 7.



The IT office also noted that it has been incorrectly attributed with diagnosing the cause of Wi-Fi signal issues or connectivity issues that have been widely reported by iPad users. The university noted that information is inaccurate, as its documentation relates only to a DHCP client issue, not Wi-Fi signal or connectivity issues.



Princeton has been able to replicate the problem regularly by allowing the iPad to lock its screen before the DHCP lease renewal time, and allowing it to remain locked, with the screen off, until the DHCP lease has expired.



Princeton's workaround has users reconfigure the iPad's settings so that the screen never locks. This can be done by going to Settings, General, Auto-Lock and choosing "Never." Users must also turn off Wi-Fi before they manually lock the screen, turn the iPad completely off (rather than just locking it), or simply leave the iPad on without locking the screen.



"We recognize that this workaround represents some inconvenience to the iPad customer," the documentation reads. "We view the workaround as a temporary workaround to allow these customers the opportunity to use their devices on the campus network until there is a fix from Apple."



Soon after the iPad was introduced earlier this month, users began to report connectivity issues with the device. One of the most common problems experienced relates to rejoining a Wi-Fi network after the iPad has been restored from sleep. Apple responded by issuing a support document.



Wi-Fi is currently the only method by which users can access the Internet on their iPad. Apple revealed on Tuesday that its 3G capable model, which offers high-speed wireless data over cellular networks, will be released in the U.S. on April 30.
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Comments

  • Reply 1 of 50
    I was at Princeton for an internship last summer, and I have to say that their network is ridiculous. My MacBook Pro got banned for a couple days because of some detail of how VMWare Fusion shared the connection. Had to hack the os to fix it. Bottom line, OIT at princeton is a bunch of (oh shit, here comes godwin's law!) Nazis, and have the network locked down to a ridiculous degree. This nonsense doesn't reflect poorly on Apple, but on Princeton for having a bizarrely non-standard wifi network.



    C
  • Reply 2 of 50
    naboozlenaboozle Posts: 213member
    Rather nasty bug. Guess I'll just be assigning a static address at home. Anywhere else, 3G. That should suffice until the bug fix.
  • Reply 3 of 50
    walshbjwalshbj Posts: 864member
    Quote:
    Originally Posted by Celemourn View Post


    I was at Princeton for an internship last summer, and I have to say that their network is ridiculous. My MacBook Pro got banned for a couple days because of some detail of how VMWare Fusion shared the connection. Had to hack the os to fix it. Bottom line, OIT at princeton is a bunch of (oh shit, here comes godwin's law!) Nazis, and have the network locked down to a ridiculous degree. This nonsense doesn't reflect poorly on Apple, but on Princeton for having a bizarrely non-standard wifi network.



    C



    You have to wonder why there aren't tons of universities reporting similar problems.
  • Reply 4 of 50
    cam'roncam'ron Posts: 503member
    I thought the issue was that it holds an IP even while in sleep? It seems more like it is by design then anything. If you haven't left the network, why give up the IP? Maybe they should expand their subnet. This would make sense as to why it isn't a problem at other universities, they thought ahead and have a higher class subnet or supernet.
  • Reply 5 of 50
    Quote:
    Originally Posted by AppleInsider View Post


    A software glitch in Apple's iPad causes the device to continue using a network-assigned IP address after its lease has expired, according to data collected by Princeton University....



    While it's definitely a bug in Apple's software that's at the root of it, if you read the report carefully, you can see that this is a "problem" of Princeton's own making.



    20 devices (campus wide over a multi-week period), *sometimes* don't release their IP??? Seriously? And the only effect if they did absolutely *nothing* about it, would be that once in a while a user would get an "IP in use" dialogue box before they were instantly handed a valid IP?



    Wow, that's totally a good reason to ban the devices campus wide.
  • Reply 6 of 50
    mj webmj web Posts: 918member
    Requires simple software fix.
  • Reply 7 of 50
    nasdarqnasdarq Posts: 137member
    Sure, it's not Apple's fault There are a number of universities that have already banned it. AI should just probably google for more articles, they are all over the web.
  • Reply 8 of 50
    This is only one of the problems users face with wifi on the iPad it seems. I have a feeling it is not the majority of problems too. If you read all the forums(especially the official apple forums) you will see there are multiple symptoms. My disconnects happen even with reserved IPs on the DHCP server so there is zero chance that 2 devices will get the same IP address. A friend has the same problem but he gets disconnected even on wakeups. I only get disconnected every 30 minutes or hour. Signal strength is full when it happens too. If I immediately go into settings and enable wifi again it works. The iPad doesn't work at all with a second router I have(older Buffalo nfiniti wireless-N). My HP laptop, macbook air, PSP, DSi, etc all work fine with that same router. Even if I restrict it to wireless N only the macbook air works with it but the iPad doesn't.
  • Reply 9 of 50
    crimguycrimguy Posts: 124member
    According to the princeton site, they lock down, log and monitor their network more thoroughly than one would expect the average IT administrator.
  • Reply 10 of 50
    iggymiggym Posts: 1member
    This is really a user error not a bug in the product.
  • Reply 11 of 50
    ktappektappe Posts: 808member
    Quote:

    The IT office also noted that it has been incorrectly attributed with diagnosing the cause of Wi-Fi signal issues or connectivity issues that have been widely reported by iPad users. The university noted that information is inaccurate, as its documentation relates only to a DHCP client issue, not Wi-Fi signal or connectivity issues.



    And yet the title of your article is "Software-based iPad Wi-Fi problems detailed by Princeton"
  • Reply 12 of 50
    al_bundyal_bundy Posts: 1,525member
    Quote:
    Originally Posted by Cam'ron View Post


    I thought the issue was that it holds an IP even while in sleep? It seems more like it is by design then anything. If you haven't left the network, why give up the IP? Maybe they should expand their subnet. This would make sense as to why it isn't a problem at other universities, they thought ahead and have a higher class subnet or supernet.





    except when it wakes up and still has the same IP it will cause a conflict with another device that was assigned that IP
  • Reply 13 of 50
    Amazing how quick AI readers are to suggest Princeton are in the wrong here. This is clearly a bug in the iPad software, and I would guess Apple will be happy with the methodical way Princeton have isolated the bug so they will be able to re-create it and fix it easily.



    The company I work for locks down it's network to this sort of level also. Networks within companies are pretty much mission critical, and anything that misbehaves is treated as a potential threat.



    People here need to remember that just because we like Apple products does not mean Apple are infallable.
  • Reply 14 of 50
    walshbjwalshbj Posts: 864member
    Quote:
    Originally Posted by nasdarq View Post


    Sure, it's not Apple's fault There are a number of universities that have already banned it. AI should just probably google for more articles, they are all over the web.



    I saw your comment before you changed it !



    I'm not saying it's not Apple's fault. But these things go both ways: This is only getting attention because it's Apple. How many other wifi enabled devices cause similar headaches for organizations and we never hear about it?



    I used to have a Netgear router that had problems with all my Apple gear: It rarely handed out the reserved address. Without wasting time digging into it I couldn't tell who was to blame. The situation at Princeton involves more layers of equipment and software that could be to blame, but maybe they've done enough research to say without question that it's Apple's fault. But maybe they haven't.
  • Reply 15 of 50
    charlitunacharlituna Posts: 7,217member
    Quote:
    Originally Posted by nasdarq View Post


    Sure, it's not Apple's fault There are a number of universities that have already banned it. AI should just probably google for more articles, they are all over the web.



    I think I have found 5 schools that are anti-ipad. and actually none of them have banned it. just they won't be giving them away to students. And 4 of them admitted that their campus networks can't handle the potential added load which is why they won't give them away or carry them in the campus store at this time.



    Quote:
    Originally Posted by al_bundy View Post


    except when it wakes up and still has the same IP it will cause a conflict with another device that was assigned that IP



    wouldn't keeping track of assigned IPs and not duplicating assignments be a part of the network not the device software.
  • Reply 16 of 50
    aaarrrggghaaarrrgggh Posts: 1,608member
    Quote:
    Originally Posted by Prof. Peabody View Post


    20 devices (campus wide over a multi-week period), *sometimes* don't release their IP??? Seriously? And the only effect if they did absolutely *nothing* about it, would be that once in a while a user would get an "IP in use" dialogue box before they were instantly handed a valid IP?



    The problem comes as the devices get more popular. Not giving up a DHCP lease is a big deal, but I understand why it would be done (especially on networks with ridiculously short lease periods) to conserve battery life.



    I think we are coming into the dawn of the era where WiFi just stops working effectively. A single access point can't support that many users-- 50-60 on the good equipment, 20-25 on the cheap stuff. It really requires a lot more effort than it did 3-5 years ago to make things work effectively.



    If your access point is doing the DHCP (bad design), your network will come to its knees quickly. If you centralize management of the access points and have reasonable address space for the DHCP it shouldn't be a major issue though.
  • Reply 17 of 50
    williamgwilliamg Posts: 322member
    Quote:
    Originally Posted by AppleInsider View Post


    A software glitch in Apple's iPad causes the device to continue using a network-assigned IP address after its lease has expired, according to data collected by Princeton University.




    I have heard that an increasing number of universities and hospitals are banning the iPad for various reasons.



    I hope that Apple or someone else can fix that.



    Without university support, the dream of textbooks widely issued on the iPad becomes more distant.



    And medical use? That too was thought to be a promising market.
  • Reply 18 of 50
    solipsismsolipsism Posts: 25,726member
    Quote:
    Originally Posted by Celemourn View Post


    My MacBook Pro got banned for a couple days because of some detail of how VMWare Fusion shared the connection. Had to hack the os to fix it.



    You changed your MAC address, didn't you?
  • Reply 19 of 50
    williamgwilliamg Posts: 322member
    Quote:
    Originally Posted by charlituna View Post


    I think I have found 5 schools that are anti-ipad. and actually none of them have banned it..



    Princeton.



    GWU



    Cornell.



    None of them lightweights. My guess is that textbook publishers are taking notice of this trend.
  • Reply 20 of 50
    naboozlenaboozle Posts: 213member
    Quote:
    Originally Posted by charlituna View Post


    wouldn't keeping track of assigned IPs and not duplicating assignments be a part of the network not the device software.



    The device has responsibility NOT use an dynamic address without an active and valid lease. Duplicate IP addresses can be a nasty problem.
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