Princeton University Network Has Issues With iPad

[Nash Bridges]

Found this this morning:

The Princeton University IT department has issued a warning to all students who use iPads on the school's network.

The warning asked the students to refrain from using iPads on the network. It also stated that if a particular iPad was identified as the cause of a disruption that it would be banned from the campus network completely.

According to the Princeton IT department, when iPads are used on their network they are not releasing their server assigned Dynamic Host Configuration Protocol IP addresses when the lease expires.

Anyone else experiencing DHCP issues with the iPad on their network?

Source: Princeton Office of Information Technology

 

[jimbo1mcm]

Smart place??

Isn't this the place Albert Einstein hung out? And they can't figure out how to fix their server?

 

[Wild-Bill]

In other news....... most, if not all pro users on MacRumors also have issues with iPad.

Film at 11.

 

[miles01110]

Isn't this the place Albert Einstein hung out? And they can't figure out how to fix their server?

If you read the article / understood anything about networks, you'd understand how meaningless your question actually is.

 

[Aduntu]

How is this the iPad's fault? The iPad is not holding the DHCP server hostage.

 

[riverfreak]

Found this this morning:

The Princeton University IT department has issued a warning to all students who use iPads on the school's network.

The warning asked the students to refrain from using iPads on the network. It also stated that if a particular iPad was identified as the cause of a disruption that it would be banned from the campus network completely.

According to the Princeton IT department, when iPads are used on their network they are not releasing their server assigned Dynamic Host Configuration Protocol IP addresses when the lease expires.

Anyone else experiencing DHCP issues with the iPad on their network?

Source: Princeton Office of Information Technology

Does this mean they are banning Windows boxen too? This is a CLASSIC problem at meetings and conferences where Windows machines never release their addresses and all available IPs are quickly exhausted.

 

[NogbadTheBad]

I bet they have a long lease period and there are loads iPads on the network.

Setting a long lease duration cause addresses to be shown as allocated and unable to be reclaimed, even if a device isn't using the address.

Setting a lease duration too short may cause excessive DHCP traffic on the network as DHCP clients attempt to renew their address leases.

Devices don't actually release their IP addresses, half way through the lease they request to re-use the IP address.

Anyhow if these "iPads" were taken home and used, they'd use non Princeton IP address.

 

[anthonymoody]

I bet they have a long lease period and there are loads iPads on the network.

Setting a long lease duration cause addresses to be shown as allocated and unable to be reclaimed, even if a device isn't using the address.

Setting a lease duration too short may cause excessive DHCP traffic on the network as DHCP clients attempt to renew their address leases.

Devices don't actually release their IP addresses, half way through the lease they request to re-use the IP address.

Anyhow if these "iPads" were taken home and used, they'd use non Princeton IP address.

What are these "iPads" of which you speak?

 

[NogbadTheBad]

What are these "iPads" of which you speak?

OK change "iPads" to any Apple devices, I'm sure the Princeton network admins are smart enough to look at the mac addresses in their DHCP leases

 

[err404]

The description sounds legit and they are taking the correct action by banning the machines. I'm a bit surprise that I haven't heard about this anywhere else.

 

[err404]

I bet they have a long lease period and there are loads iPads on the network.

Setting a long lease duration cause addresses to be shown as allocated and unable to be reclaimed, even if a device isn't using the address.

Setting a lease duration too short may cause excessive DHCP traffic on the network as DHCP clients attempt to renew their address leases.

Devices don't actually release their IP addresses, half way through the lease they request to re-use the IP address.

Anyhow if these "iPads" were taken home and used, they'd use non Princeton IP address.

No, the issue has nothing to due with lease duration. They claim that the iPad isn't requesting a renewal and just continues to use the IP even after it's expired. This is leading to collisions after the IP is return to the pool and given to a different device on the network. If true it's a flat out bug.

 

[miles01110]

If it's an actual bug, I'm wondering why more college networks aren't reporting this. I haven't actually looked around so maybe that's not the case.

 

[Alrescha]

If it's an actual bug, I'm wondering why more college networks aren't reporting this. I haven't actually looked around so maybe that's not the case.

I have experienced at least one DHCP bug. My iPad works fine at home and at work with Airport Extreme and Airport Express, but doesn't work on the free wifi at my local pub. I did discover that everything worked if manually picked an IP address on the appropriate network - which is why I say there is a DHCP bug.

Of course this kind of behavior will cause problems on the network as there is a good chance of causing an IP address conflict. I wonder if thousands of Princeton students have figured out that their <non-working?> iPads work fine if they manually configure an IP address? It would certainly look like the iPads weren't releasing their IP address when the lease expired.

A.

 

[err404]

If it's an actual bug, I'm wondering why more college networks aren't reporting this. I haven't actually looked around so maybe that's not the case.

The layout of Princeton is pretty compact compared to a lot of schools leading to a very high number of devices per hot-spot.

There tends to be a lot of money there, raising the density of iPads further.

Their IT staff is above average compared to other schools. A lot of IT departments may have seen a few complains of IP collisions, but not researched the cause.

 

[err404]

I have experienced at least one DHCP bug. My iPad works fine at home and at work with Airport Extreme and Airport Express, but doesn't work on the free wifi at my local pub. I did discover that everything worked if manually picked an IP address on the appropriate network - which is why I say there is a DHCP bug.

Of course this kind of behavior will cause problems on the network as there is a good chance of causing an IP address conflict. I wonder if thousands of Princeton students have figured out that their <non-working?> iPads work fine if they manually configure an IP address? It would certainly look like the iPads weren't releasing their IP address when the lease expired.

A.

That would be funny. A grass roots movement of non-technical students setting static addresses!

 

[NogbadTheBad]

No, the issue has nothing to due with lease duration. They claim that the iPad isn't requesting a renewal and just continues to use the IP even after it's expired. This is leading to collisions after the IP is return to the pool and given to a different device on the network. If true it's a flat out bug.

Any good DHCP server should ping the IP address its trying to hand out before handing out the IP address, QIP does.

I'm sure its a server issue.

It would be interesting if someone reading this forum could show us the lease time

 

[hugodrax]

Found this this morning:

The Princeton University IT department has issued a warning to all students who use iPads on the school's network.

The warning asked the students to refrain from using iPads on the network. It also stated that if a particular iPad was identified as the cause of a disruption that it would be banned from the campus network completely.

According to the Princeton IT department, when iPads are used on their network they are not releasing their server assigned Dynamic Host Configuration Protocol IP addresses when the lease expires.

Anyone else experiencing DHCP issues with the iPad on their network?

Source: Princeton Office of Information Technology

They should be able to fix this, with those 60K annual tuitions per student they could upgrade the DHCP server or maybe buy new Wireless APs instead of using 5 year old models.

 

[Sleazy E]

i am sure they will be able to collectively figure it out over there somehow

 

[Nash Bridges]

From the responses I guess that no one else has had DHCP issue with their iPad.
Correct?

 

[err404]

Any good DHCP server should ping the IP address its trying to hand out before handing out the IP address, QIP does.

Agreed and I thought about that. However, the iPad is a mobile device and frequently asleep or out of WiFi range. There is a lot of opportunity for duplicate IPs to be handed out while an iPad is not responding. DHCP lease duration doesn't matter if the iPad is really ignoring it.

These also could tie into the acknowledged issue that the iPad is having with multiple access points having the same name.

 

[fishepa]

I can't imagine any regular home user would experience an issue with running out of IP addresses on their network.

 

[err404]

From the responses I guess that no one else has had DHCP issue with their iPad.
Correct?

Even if our iPads show this same behavior, it would only show up in very specific large scale environments.

 

[err404]

I can't imagine any regular home user would experience an issue with running out of IP addresses on their network.

The issue isn't with running out of IP's, it's with the iPad continuing to use an IP after it has expired. This could cause issues even with few IP's in use.

 

[paleck]

Could the problems have anything to do with the scattering of reports that the iPads aren't keeping their time properly when sleeping. If the iPad wakes up still thinks it is the same minute that it went to sleep at. Then it would have no reason to either try to renew their existing lease or release it. It would just assume that it still has X minutes/hours/etc of time left on it's lease before it has to do something about it.

In a perfect world a device going to sleep SHOULD release it's IP and then request a new address when it is woken back up.

 

[err404]

In a perfect world a device going to sleep SHOULD release it's IP and then request a new address when it is woken back up.

A device doesn't need to release the IP. There are many cases where releasing isn't even possible. For example if the user walks out of range or the device just crashes abruptly. All the device needs to do is respect the lease duration. If the lease expires at 1:00pm, it should not be using that IP at 1:01pm (without a renewal). So your point about losing time does make sence.