[Ben]

http://www.reghardware.co.uk/2009/12/21/o2_down_yet_again_again/

DHCP on the blink again, leaving people with no connectivity. Nice to see the fun continue after I'm long gone :D

[hecatae]

mobileweb apn was working, nothing else was

[Hands0n]

It is simply amazing at how O2 have managed to screw up their mobile data network in such classic style. Not only has the DHCP been flaky - and I suggest that has been going on for very much longer than O2 would care to admit - but also their Visual Voicemail and MMS have not been working.

It is possible that these other services were impacted by the DHCP mess but I very much doubt it - these systems and services would not be using DHCP-allocated IP addresses. Much more likely is that several failures have occurred in O2's network infrastructure and that DHCP was the most significant.

To O2's shame - their silence on this has been astonishing and unwelcome in equal measure. By keeping quiet they have ensured maximum inconvenience to their customers who would have struggled along thinking the fault may be with their own equipment!

Thanks for nothing very much O2. I'm off at the earliest opportunity. Off to someone who has been demonstrably more supportive.

[DBMandrake]

Actually, if the problem is that they can't allocate IP addresses to PDP data circuits (data connections opened over GPRS/EDGE/3G) as the reports seem to suggest, it could in fact affect MMS and Visual Voicemail as well.

MMS works by opening an http data connection to send/receive an image, usually over a separate PDP data circuit than normal data, and depending on provider using a different APN as well.

Visual voicemail downloads voice messages as audio files, also via a separate PDP data circuit and APN.

Both are not counted against your normal data usage but both are still TCP/IP data sent over virtual circuits and need an ip address allocated for them to work. No ip address allocated at the phone end of the PDP circuit and the service won't function.

More coverage in the media about the issue, it seems that people are definitely not happy:

http://www.tuaw.com/2009/12/22/o2-network-issues-hinder-iphone-users/

It really does seem as if O2's network is crumbling around them due to lack of re-investment in their infrastructure, and it's finally coming back to haunt them...

[Hands0n]

Very interesting - I've not come across the expression "PDP data circuit" and Google draws a blank also :D So spill the beans, what is going on here? Is this exclusive inside mobile networking territory, proprietary stuff? You've suggested that these are "virtual circuits" so are these VPN then, perhaps using a unique port that can be excluded from the data accounting?

It is a real shame that O2 can't simply come clean on this. Its not as if the event is of a minor nature, only affecting a few people, and mostly those who will not wipe their SIM with a clean dry cloth!! :rolleyes: This has made all social networks such as Twitter and Facebook (but not exclusively those). Now the various technical media are getting wind of it. They really need to be a bit more up front and honest.

Sorry O2 - but no amount of media offers is going to deflect from the simple fact that your network took a major hit, and remains flaky as of this evening. At least have the balls to stand up and tell the truth. You'd be respected an awful lot more for doing that than this game of cat and mouse!

Lots of O2 users commenting here --> http://forum.o2.co.uk/viewtopic.php?t=32968

[DBMandrake]

Well my terminology was a bit duff, so I looked it up to make sure I wasn't talking a load of nonsense... :D PDP stands for Packet Data Protocol, is part of the GSM spec, and is how TCP/IP data is sent over GSM/3G:

http://en.wikipedia.org/wiki/Packet_Data_Protocol#PDP_Context

Basically each PDP context is a tunnel - a bit like a VPN tunnel yes, or perhaps a better analogy would be the old PPP protocol used on dialup internet - where you have an ip address at each end of the link, and you can route traffic via it.

The clever thing about PDP contexts is you can have more than one active at a time and you can bring them up and take them down as needed, each one gets a separate ip address, and potentially can connect to a different network at the other end. (Or different part of an operators network)

Imagine a PC with more than one ethernet card connected to more than one network at the same time and you get the idea.

So the visual voicemail server could be on a "private" network using private ip addresses with no connection to the network your phone accesses the internet by, and the phone can effectively create a tunnel to that network to access it when needed. Same applies for MMS.

Although the spec apparently supports up to 11 simultaneous PDP contexts, I think the iPhone is limited to a maximum of 4 at a time -

Internet Data (safari, mail etc)
MMS
Visual Voicemail
Tethering

The thing that decides what network at the other end each tunnel connects to is the APN (and username and password) which you can see in the Settings for Internet Data and MMS but is hidden for visual voicemail and tethering, and configured in the carrier settings (ipcc) file. The iPhone is very flexible with how the PDP contexts can be configured, for example most operators choose to have tethering going over a separate PDP context with a separate APN so they can tell tethered traffic apart from handset traffic for billing purposes, (and disable tethering if you don't have the addon) but you CAN configure it to do tethering over the primary internet data APN with the right custom ipcc file...(making it impossible for the operator to tell apart tethered and handset data, or disable tethering without an addon - one reason Apple has gone to great lengths to lock down the tethering settings)

Regardless of all this though, even if all data were being sent by the same tunnel, (which for some operators it is for MMS) there is no reason why the operator has to count that data against your usage - for internet usage they simply count your traffic at their border router rather than where it comes in from you - thus all traffic from your phone to their own servers (MMS, Visual Voicemail, local portal etc) doesn't count against usage while internet access does.

[Hands0n]

Ah, thanks for the explain. That all makes sense. It is the PDP context itself that carries a GPRS or other traffic. Neat, and then they can meter on the PDP context that is carrying the GPRS and ignore the others - as long as they too are not chargeable.

I had not seen this description of how the data was carried and had assumed it was all over GPRS but specific TCP ports for each messaging type.

Its funny really, but with mobile networks the technology and terminology is so very different to more conventional terrestrial networking. They acronyms are eye watering by comparison :D But make complete sense when described and laid out ..

[miffed]

but also their Visual Voicemail and MMS have not been working.





Just as an aside (sorry to go OT ) , I've heard Vodafone aren't bothering with VV ?

....and are they still doing that thing where they don't let MMS's come out of your message bundles ?

[Ben]

Just as an aside (sorry to go OT ) , I've heard Vodafone aren't bothering with VV ?

....and are they still doing that thing where they don't let MMS's come out of your message bundles ?
I hope that's not true, I love Visual Voicemail.

MMS are not included in SMS allowances on Vodafone, AFAIK.

[miffed]

http://forum.vodafone.co.uk/index.php?showtopic=45207

I am sure sometimes I live in some weird parallel universe:D

These occasional glitches with o2 never seem to affect me , I think I'll stick with a network that has occasional problems with these features , rather than move to one who can't even be bothered to implement them ! :D