Re: Broadband Update - P2P being throttled around the world
- From: Mothy <mothy@xxxxxxxxxxxx>
- Date: Fri, 09 Sep 2005 12:51:10 +0100
Flyiñg Ñuñ 2°°5 + wrote: snipped
So that's what was happening to my 2Mbps connection a couple of weeks ago, when the download speed plummetted to 237kbps. :(
FN This is very lengthy but I found it a good and informative read once more. This message is from:
news://usenet.plus.net:119/opswt0fnuyyf6049@xxxxxxxxxxxxxxxxxxxxx
The following two posts have been taken from
http://portal.plus.net/central/forums/viewtopic.php?t=32675&postdays=0&postorder=asc&start=0]this thread
and as per a suggestion I’ve made them a sticky on the forum and posted them here as there is a lot of information here that may answer a lot of questions customers may have.
Again sorry for the forum link, but I want to ensure you can see the posts in context.
----------------------------------------------------
[quote="chesterfield"]I don’t mean to scaremonger from my post, but that’sthe view I take - you are of course entitled to your own.[/quote]
Indeed, but I'm sure you agree that some posts from some people (no namesmentioned) just seem to attack and scaremonger just for the sake of it. Ican understand genuine concern, and where information is unclear or
missing, or where it's not written in an easy to understand way.
Some of the things we do behind the scenes are difficult to explain and
some will rely on prior knowledge. We know that lots of customers aren't
interested in how their connection to the Internet works, and so long as
they can turn on their PC and go to say eBay that's fine. There are other customers that want to know all the finer details of everything that happens. And there are plenty of others in between.
If I can try and clear things up, please allow me to do so and try and put your mind at ease.
[quote="chesterfield"]I can say that I have not noticed any degradation of service on my connection[/quote]
Me neither, and I'm pretty sure we aren't alone. My connection works fine all the time, Usenet downloads at 230+KB/s at any time, other P2P is good if the speed is there from the source(s), pings are good and low, no packet loss, browsing nice and snappy, I could go on, but I won't.
Yes, we are seeing customers who are reporting problems, but so too are
customers on other ISP's and no matter what, an Internet service will never be 100% problem free for every customer, and I'm sure you don't expect that.
I'd also say that there are a number of reasons for the increase in faults and problems that are being reported, the first is simple in that we've never had as many customers as we have at the moment, so it's likely the volume of faults will increase as the customer numbers increase.
Additionally, BT Wholesale have record numbers of faults being reported to them by all ISP's, again in part this is because of the increase in
broadband customers in the UK, but also there has been an increase in early life failures with 2Mbps services. This has meant that the limits for 2Mbps have been tightened up as we mentioned a few weeks ago.
Also with the volume of faults on the up, the turn around times have been on the up as well. The change of limits for 2Mbps is helping as are other measures they are taking and turnaround times are now heading back down as are the fault volumes.
The rollout of MaxDSL is going to help the fault volumes too as the RAMBO kit at the exchange should help to ensure that lines aren't provided at speeds they can't support.
[quote="chesterfield"]however I am not running at 2mb, so I am not
expecting as larger piece of the pie as many others, perhaps this is why I do not see the effects that others are apparently seeing.[/quote]
I would have said that was unlikely, but possible. I've looked at some of the speed problems that are being reported and there seem to be several different causes, and in some cases a combination of causes.
The first case, and probably the most common, is where the slow down is
across the board on everything. Our speed test shows a slow down, as does ADSLGuide, as well as downloads. In these cases the BT Speedtester will determine whether the cause of the speed decrease is on our side of the network, or on BT's (or customer equipment, but that's easy to rule out of the equation). So far most, if not all the cases I've looked at in this type of scenario have been caused by contention at exchange/VP.
When an exchange is flagged up as running "hot" by BT it will show as red on the exchange checker. However, the data on the exchange checker can be a couple of weeks out of date due to how the data is collated and presented.
Also, it's possible for an exchange to see contention but still be within the design limits. You just need to ask Kitz about the recent speed problems she's had because of exchange contention.
Other speed problems we're seeing reported are where the BT Speedtester shows the speed as normal but a particular application or protocol is showing as being slow.
In the main we are talking about P2P and Usenet speeds, although I have seen reports of sluggish web browsing and ftp and increased pings.
In these cases we need a bit more investigation because it isn't always obvious what the cause or causes may be.
For example, if your BitTorrent speeds are normally 230KB/s, but you have a 10% decrease on the BT speedtester from your normal speed and you are downloading when the network is busiest, so you may see a further up to 10% cut due to the traffic management then your speed could be down to 230 * 0.9 * 0.9 = ~ 185KB/s.
If the BT Speedtester drops by more than 10% then that figure falls
further. Even with a normal BT Speedtest, you could still see an up to 10% decrease at peak because of the traffic management taking you to ~205KB/s.
Also, the nature of P2P traffic means that it is a very bad measurement of speed. Again with BitTorrent, the speed you can download at on a particular torrent is determined by several factors. The number of people uploading and how fast they can upload, how many people are downloading and how much of the data you can grab for yourself, the load on the tracker can be a factor as high load may stop you connecting to all of the seeds, and the speed of your upload can cause a decrease in download because if the upload is maxing out there will be little room for you "ack" packets. If the ack packets can't get through then the download speed decreases.
In a similar situation with Usenet, the number of connections you make to the server can affect the overall download speed. I know from personal experience that using one or two connections to usenet will mean that my connection doesn't max out, but 8 connections always does.
It also sound obvious but any other use of the connection will cause
P2P/Usenet speeds to decrease, but because of the way the QoS queues work it may be that an HTTP download will rank above a Usenet download and the HTTP download will take the lion's share of the bandwidth. Similar a small increase in uploads might cause a large decrease in download speeds. E.g. upload a torrent a 20KB/s might cause your Usenet download to drop from 220KB/s to 110KB/s.
Going back to your original point, on our network you are allocated the
same share of the network for your account type regardless of what your
sync speed is. The determining factors of where your account type sits and what profile it has are the account type (Plus, Premier, etc.) the account speed (up to 2Mbps, up to 4Mbps, etc.) and the PlusNet network contention ratio (10:1, 30:1, 50:1, etc.). The sync speed and BT side contention ratio aren't factors here.
[quote="chesterfield"]Yes another segment has been activated, but this only Takes the bandwidth back to somewhere near what was available in January - and thousands more have joined since then.[/quote]
There are two factors here. First a 622Mbps pipe has greater efficiency
than 4 x 155Mbps pipes. The architecture of the pipes means that the
overheads are greatly reduced, 622's are Ethernet connections, whereas
155's are ATM. As such a single 622 pipe is near enough the equivalent of 5 x 155Mbps pipes in terms of how much "customer data" they carry. We now have 17 active segments across the 622Mbps pipes, had we stayed on 155Mbps that would be the equivalent of 21 x 155Mbps central pipes.
The second big factor here is that yes, we've seen considerable increase in customer numbers this year, but the actual growth has been in Broadband Plus customers, both with new signups and customers changing from Premier (or legacy equivalent) to Broadband Plus.
You can see from the utilisation graph
http://www.plus.net/support/adsl/adsl_utilisation.shtml
that Broadband Plus usage peaks at around 225Mbps. In the same time period, Premier has been fairly static, so although customer numbers have increased, the amount of peak time bandwidth, which is what drives the number of pipes that are required and thus the main cost factor, has only marginally increased.
[quote="chesterfield"]In terms of "sorting" I mean explaining to customers exactly what shaping takes place and when - also what are the limits before we get a warning mail? PlusNet seem the only ones able to determine what sustainable and unsustainable usage is - everyone else just has to guess at the limits.[/quote]
I think I've explain the shaping elsewhere, but I'll see if I can sum it all in one place.
Essentially there are two processes that take place on the traffic as it flows through the network.
First, the traffic hits the Ellacoya e30's. Several things happen here,
initially the Ellacoyas use deep packet inspection to see what the traffic is. They then place a rate limit if needed on overall level of P2P traffic going through. Finally the Ellacoyas will apply the profile settings to the traffic.
Once through the Ellacoyas the traffic is divided into three input queues - gold, silver and bronze.
For reference
Gold = http/https, and email Bronze = Usenet & P2P Silver = Everything
(makes a little clearer to list them in that order).
The traffic in these three input queues is then put into a single output
queue. So long as the three inputs are less than the output no traffic is dropped at this stage.
If the amount of traffic is greater than the input queues then traffic in the bronze queue would start to get dropped. The amount of traffic dropped would be just enough to ensure that all gold and silver went through and as much of bronze as possible. What traffic is dropped is also proportionate to the overall level of that type of traffic. As P2P traffic as by far and aware the largest traffic on the network and is far larger than Usenet, this is the traffic that will see the first drops. The design of this management means that except under exception circumstances you wouldn't see more than a 10% drop in P2P traffic. It's possible for Usenet traffic to be dropped too, but because of the usage patterns on Usenet at the moment, usage peaks at 1am whereas HTTP peaks earlier in the evening, and P2P is pretty constant throughout the day, therefore you would generally only see P2P dropped.
Also as each ERX and Ellacoya work independently it's possible that speeds could be a little different depending on which gateway you connect to.
This is another reason for the implementation of idle timeouts, at the
moment we have plenty of spare sessions, but it's possible that a single
segment could have lot's of idle connections. This isn't an efficient use of the network because while these are idle and not using bandwidth,
another segment could be seeing a larger than necessary decrease in speed.
Also, if there is a major service outage because of a loss of one or more central pipes, the number of available sessions would be reduced and so by freeing up unused sessions we can a) ensure that everyone can connect and b) free the Ellacoyas and the ERX QoS queues we can deliver a level of service so that people can still get their emails and browse the web, etc.
Regarding the limits and what constitutes unsustainable usage, this is
something we actively looking at. Neil recently posted what we say said was considered unsustainable which was in effect 100GB for a £21.99 Premier up to 2Mbps account, with higher figures for the higher priced Premier accounts.
The exercise we did last month where we contacted customers whose usage was above those unsustainable levels will be done again later this month where we will ensure that exactly what is unsustainable is clear.
[quote="chesterfield"]I agree, why would you want to make the service worse for your customers? [/quote]
Exactly, we wouldn't. Our customers are our life blood, it's our existing customers that recommend us to friends and family. We want to make things the best that we can.
[quote="chesterfield"]I don't know, and it would seem neither do PN - why introduce idle timeouts on to a broadband package? The whole ethos around the entire planet is "always on", while I agree this makes the network more efficient for those on it, it doesn’t help those who may need their always on connection - so good for some = bad for others.[/quote]
You've got to look forward, you've got to plan ahead and ensure the service you are delivering is the best possible. As I've said above we've seen what could happen and want to ensure that this doesn't happen. I've used the water example before, so I won't use it again, but service could still be considered "always on" even on Broadband Plus. We are removing the "always on" references though and won't be going down that route, but for those that do need the PPP session staying up all the time they can always change to Premier or PAYG.
In most cases though to reconnect a disconnected connection will be a 2
second job to click reconnect, for many using routers it will automatically reconnect.
[quote="chesterfield"]Why introduce traffic shaping on your "premier" products? There could be a multitude of other options to increase efficiency without tampering with your most elite of home user packages?[/quote]
The reason is simple, to ensure the best quality of service for all
applications when the network is busiest. From experience at a previous ISP I've seen situations where the central pipe hits capacity and it isn't nice for anyone. Everything sees slowdowns, packet loss and ping times. With proper network management we can ensure that the latency sensitive applications are protected and that the customers paying the higher subscriptions see the benefit of this through a higher slice of the available bandwidth.
The ISP that doesn't have network management is the foolish ISP. They are the ones that don't care about their customers, that are happy to see increasing costs, that aren't planning for the future.
We are here to deliver the best Internet service we possibly can, we aren't here for the short-term, we are in this for the long haul. We are planning now for the future and planning now to give more services and options for our customers.
----------------------------------------------------------------
[quote="chesterfield"]Thanks for that post, you have put some effort into that. It certainly goes some way to explaining what is taking place at the moment.[/quote]
No problem, that's exactly what I want to do. I want to ensure that our customers get the answers to the questions they are answering. As we all know not everyone will like all the answers, but I least want to ensure that where customers don't understand or know why we are doing something that the information is there for them.
[quote="chesterfield"]I still feel that the method other ISP's are taking (spare capacity and higher prices over maximising efficiency) would seem to be the way many P2P folk would want to move. [/quote]
This is certainly possible, however we have to look at our customer base as a whole rather than just certain people and certain types of usage.
We also need to look towards the future and what's going to happen when faster speeds become available to more people.
We all know that 8Mbps speeds are just around the corner as such we have already planned for this. The question I would ask is how much would it cost to service the needs of someone using an 8Mbps connection to the max 24/7? The answer is in excess of £20,000 per year.
If you have 20 x 8Mbps customers all maxing their connections 24/7, then between them they are using the equivalent of a single 155Mbps segment. At over £400,000 per year for a 155Mbps segment that's £20,000 per customer.
It's unlikely that any ISP would be able to sustain that amount on CBC without some kind of network management or bandwidth control.
As we've seen with the measures that other ISP's have taken, where PlusNet lead others will follow.
From an economic point of view it just doesn't make sense to have empty pipes lying around just in case you need them. To have an empty 155 as I said above just lines BT's and VAT man's pockets with £400,000 of your customers' hard earned cash for little or no return.
To utilise you central pipes to the max means you keep your costs down and you keep your prices down.
For any ISP using CBC or UBC then they will have done the same maths as us, and looked at the same equations as us and if they want to stay in business will have come to the same conclusions as us regarding sustainability (granted they may come up with different points at which usage is unsustainable), but for an ISP to offer an 8Mbps service using CBC or UBC I would very much doubt they can do that at a price people want to pay without looking long and hard at how they manage their network. For reference standard charging won't offer the faster speeds and LLU obviously has different costings.
[quote="chesterfield"]I personally feel that PN are trying too hard to be a jack of all trades rather than a true premier service provider or indeed a true low budget provider.[/quote]
The choice of services we offer is pretty much suitable to everyone (bar those with requirements to do download vast quantities), hence the different choices of account type from Plus to PAYG to Premier.
[quote="chesterfield"]It may be the case that measures being taken will improve overall performance of latency sensitive applications for those paying a premium, but some of those on the premier package (paying a premium) may consider P2P as their most important use of the net - should they not expect to get a premium service because you consider the traffic to be less important than they do?[/quote]
P2P isn't latency sensitive, if you start seeing packet loss and ping spikes then all that happens with P2P is that it slows down a bit. By managing the network in the way that we do, when the network is busiest the services that are affected the most are protected and P2P sees exactly the same sort of performance (give or take a percentage point or three of throughput) as if we weren't managing the traffic at all.
P2P usage is pretty constant throughout the day, and we are ensuring that we deliver the best performance on P2P that we can, but when the network is busiest the P2P traffic would slow down along with everything else, so it isn't as though they really lose anything because it would have dropped by 5-10% in speed anyway.
[quote="chesterfield"]I agree that any issues experienced by people on the products that have idle timeouts would be very minor (those wanting to remote connect may suffer more)[/quote]
To be honest I wouldn't have thought on Broadband Plus that would be very high because of the dynamic IP. Yes, they could set up something like DYnDNS, but if you are going to that effort then in all likelihood you would probably be looking at Premier anyway.
[quote="chesterfield"]but I doubt it would be these issues which would cause PN the most damage - I would think that being known as one of the only (if not the only) providers to implement timeouts on broadband will do more harm to PN than any tickets raised. [/quote]
I'm not so sure that it will. The session limits on BT's central pipes are the same for all ISP's. BT Wholesale were looking at developing BT Central Extra which would allow the session limit to be increased, but this was dropped. Discussions are ongoing with BT Wholesale, and not just from ourselves but other ISP's too. As I said above where PlusNet lead others will follow.
[quote="chesterfield"]Could I suggest that some sort of scale be added to the utilisation charts as this may quell some of the storm.[/quote]
I can ask, there have been several suggestions regarding changes to the graphs so I'll make sure they are all raised.
[quote="chesterfield"]May I be so bold as to suggest your reply or the main sections of it be posted as a sticky? It could help people before they post similar concerns or questions.[/quote]
Good idea. Might be worth adding to the existing sticky.
With Regards,
Dave, -- | Dave Tomlinson Broadband Solutions For | Customer Support for Home & Business | PlusNet plc @ http://www.plus.net + ----- My Referrals - It pays to recommend PlusNet -----
-- Mothy
Reality is an illusion caused by lack of alochol. Let him who is stoned cast the first sin. Humpty Dumpty was pushed. .
- References:
- Broadband Update - P2P being throttled around the world
- From: Mothy
- Re: Broadband Update - P2P being throttled around the world
- From: ray
- Re: Broadband Update - P2P being throttled around the world
- From: Flyiñg Ñuñ 2°°5 +
- Broadband Update - P2P being throttled around the world
- Prev by Date: Re: FN
- Next by Date: Re: Not good news. :-(
- Previous by thread: Re: Broadband Update - P2P being throttled around the world
- Next by thread: Moby number
- Index(es):
Relevant Pages
|
Loading
