tag:blogger.com,1999:blog-3993498847203183398.post3601121797345798451..comments2024-03-28T09:19:27.451+00:00Comments on RevK<sup>®</sup>'s ramblings: Contention ratiosRevKhttp://www.blogger.com/profile/12369263214193333422noreply@blogger.comBlogger12125tag:blogger.com,1999:blog-3993498847203183398.post-772975846091024082017-05-09T12:16:41.809+01:002017-05-09T12:16:41.809+01:00I was on the same cable modem trial too, Rob. (Man...I was on the same cable modem trial too, Rob. (Manchester, right? Around 1998 if memory serves me correctly.)<br /><br />It was of course pretty magical to have an 'always-on' connection, but I think we all learnt a lot about the practical effects of contention through this!<br /><br />I do remember staying up until 3am to download news from usenet, as that was pretty much the only time I'd ever see the full speed.<br /><br />Hard to imagine an ISP trial, even in those days, thinking that was a good idea to put 200 customers with 10mbps cable modems behind a single 64kbps link :) It was certainly more usable when they upgraded to 2mbps, albeit after some months if not years. I bet Nynex learnt a lot from our usage, as well..<br /><br />JMHAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-14190753823345432822017-05-08T10:18:55.276+01:002017-05-08T10:18:55.276+01:00Graham Cobb: That might help me choose between two...Graham Cobb: That might help me choose between two ISPs who are both selling BTW FTTC connections, but how does it help me choose between ADSL, FTTC, FTTP, Coax, etc? Fundamentally, anything that you aggregate across multiple addresses isn't terribly useful because what can be offered varies so widely depending on your location.Steve Hillhttps://www.blogger.com/profile/09798286430189689578noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-11656521146499813722017-05-06T12:08:21.180+01:002017-05-06T12:08:21.180+01:00Not sure if you were referring to my comment to yo...Not sure if you were referring to my comment to your earlier post. In any case, I completely agree that contention ratio is not a useful thing to quote (or even to try to define). However, I believe that the effects of it are a very important quality differentiator between ISPs and something that an ISP like AAISP needs to be able to promote.<br /><br />I think the problem is that the discussion has got into a lot of discussion of technical internal analysis and metrics. What should be measured here (and used in advertising) is a standardised quantification of customer experience. Telcos learnt this a long time ago for voice when they stopped quoting bandwidth, latency and jitter and created MOS. We need a MOS for broadband.<br /><br />My suggestion is that CAP should be defining a "UK Broadband MOS" based around something meaningful to UK consumers. It could be as simple as "90-th percentile effective streaming speed for BBC iPlayer in the busy hour". That would be a metric useful and meaningful to almost everyone in the UK.<br /><br />Sure, it would encourage some specific ISP behaviours to optimise iPlayer access (special peering arrangements, hosting of BBC CDNs, etc) but those would probably help most consumers and would include things that are beneficial for accessing many other sites as well.<br /><br />If it got to the stage where that particular metric was distorting ISP behaviour unreasonably then it would be time for CAP to step in and define a new metric. Meanwhile we would have had a period of several years where quality-focused ISPs such as AAISP could effectively advertise their differentiated value.<br /><br />Maybe this suggestion is too simplistic, but I think the need is for a MOS, defined in a way which promotes the behaviour consumers want to see. Of course, business connections would need to compete in a different way.<br />Graham Cobbnoreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-54635246302266774672017-05-06T10:07:14.047+01:002017-05-06T10:07:14.047+01:00A very interesting point and discussion. A very interesting point and discussion. ebreyithttps://www.blogger.com/profile/00108579642499534695noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-36286773380909856692017-05-06T09:31:56.472+01:002017-05-06T09:31:56.472+01:00It used to be so much simpler. My first is (dial u...It used to be so much simpler. My first is (dial up) had 16 oncoming lines and 200+ customers.. Contention was most evident at the engaged tone..<br /><br />1996 I was on the local cable company (NYNEX) cable modem trial. 200 of us. Mix of customer types. All sharing a 64kbps, later 2mbps, outbound link. You could tell immediately when others were using their connection! Robhttps://www.blogger.com/profile/15492761714688454925noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-13734065427473350072017-05-05T18:24:11.098+01:002017-05-05T18:24:11.098+01:00There's a term I haven't heard in a long t...There's a term I haven't heard in a long time.<br /><br />Last term I heard that term I was doing first line training for o2 broadband (I was there from official launch day to the day o2 decided customer service wasn't core to the function of being a Telco) and we were told that we didn't have one. If we needed more capacity then regardless of what capacity was already there we simply got more.<br /><br />How true that was I really can't say though.. o2 did have a habit of lying to its staff... lying about the outsourcing and sale to sky days before they were announced, lying about the value of TUPE, lying about the newspaper report about the plan to shut the centre 2 years after outsourcing...Chad Hhttps://www.blogger.com/profile/06466797076721870606noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-14936916155303862272017-05-05T15:42:16.804+01:002017-05-05T15:42:16.804+01:00Isn't the (theoretical) "contention from ...Isn't the (theoretical) "contention from the cab" figure already differentiated into three tiers in terms of priority? ie 80/55/40<br /><br />I know 80 gets higher priority between cab and head-end than 40, logical 55 does too.<br /><br />I don't suppose you have enough customers but given your monitoring systems have you ever seen any cab->head-end congestion? It surely must exist in places?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-5396594457779117852017-05-05T12:44:55.651+01:002017-05-05T12:44:55.651+01:00Shorter answer: The very fact you picked "exi...Shorter answer: The very fact you picked "exiting the ISP's network to the rest of the internet" as the point to measure is part of the problem - that is rarely the bottleneck even on really slow ISPs.RevKhttps://www.blogger.com/profile/12369263214193333422noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-14876881176084673202017-05-05T12:44:12.070+01:002017-05-05T12:44:12.070+01:00No, sorry. Just the fact that an ISP can purchase ...No, sorry. Just the fact that an ISP can purchase different "contention at the cabinet" from BT Openreach means that contention at that point as a service differentiator may be a factor in quoting a service quality metric. At present we are not seeing cabinet congestion, but if that ever does start, it will matter to the end user. Also, "exiting the ISP" is not simple either, if we have only 1Gb/s to a peering point, do we quote contention for that just because that is the link that may be used for a customer to access something, or do we quote based on the 10Gb/s link to a transit point. Both could be a bottleneck and could be used by all customers at once. Also, why the arbitrary "existing the ISP network to rest of internet" - why does that point matter to the end user rather than any other point? If Level 3 started a broadband offering, where would that be for them as they also run a transit network? What would be nice with your proposal though is an ISP with a BT wholesale link that is heavily limited because they do not buy much bandwidth from BT will be able to quote low contention as they can afford a huge connection on their "exit to the rest of the internet" as such links are much much cheaper by comparison to BT wholesale interconnects. It really is not simple to define, and even harder to avoid someone "engineering" a good result, which you also have to consider.RevKhttps://www.blogger.com/profile/12369263214193333422noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-59973606225690057622017-05-05T12:35:17.682+01:002017-05-05T12:35:17.682+01:00I think you're throwing in a lot of irrelevant...I think you're throwing in a lot of irrelevant material here. Clearly when someone asks about "the contention ratio of an ISP", what they want to know is the contention ratio of the most contended link that is part of the ISP's responsibility to the customer (eg, between exiting the user's house and exiting the ISP's network to the rest of the internet). That doesn't seem difficult to define unambiguously, and while it may be hard to measure for the reasons you outlined, it's a concrete figure.<br /><br />That figure may not be a useful indication of ISP quality for the reasons you outline, but I don't think it's fair to claim that it's confusing as to what you should actually measure to get the figure.Nick Johnsonhttps://www.blogger.com/profile/04083452977458707717noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-439530163291215642017-05-05T11:53:48.639+01:002017-05-05T11:53:48.639+01:00All of the stuff in BT and TT involves sharing lin...All of the stuff in BT and TT involves sharing links with other people that are not A&A customers, do we could not work out total usage of such links to see if congested. Simpler is if TT/BT tell us a link is congested. But we can see from LCP echoes we do on every line every second when that happens which is simpler than trying to do the maths when we don't have the data. In general the BT and TT back-haul is not congested.RevKhttps://www.blogger.com/profile/12369263214193333422noreply@blogger.comtag:blogger.com,1999:blog-3993498847203183398.post-6180208473748715422017-05-05T11:50:55.993+01:002017-05-05T11:50:55.993+01:00Assuming you can get metrics from BT/TT, and colle...Assuming you can get metrics from BT/TT, and collect them from your network, you should be able to plot the bandwidth headroom for every link between the CPE and the internet at large. Since you know which links may have been needed to transfer traffic from each customer to the rest of the internet, you can figure out the proportion of time that each user was relying on a link with no headroom (and therefore the proportion of time that user's connection speed was limited by congestion either within BT/TT or within the ISP).<br /><br />Aggregate that across all the customers, and surely you can get some meaningful statistics - the average percentage of time customers see their internet connection congested, standard deviation of that, etc.<br /><br />Of course, it relies on BT and TT to provide metrics, but it seems to be a reasonable way of quantifying what kind of performance a customer should expect: an ISP with a rubbish internal network is going to produce a higher "average percent of time spent congested" figure than an ISP that tries to avoid being the bottleneck.<br /><br />That said, it incentivises ISPs to get rid of customers who are on highly contended BT links for whom a less contended TT link isn't available (or similar).Steve Hillhttps://www.blogger.com/profile/09798286430189689578noreply@blogger.com