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    Upstream attenuation halved?

    This is a discussion on Upstream attenuation halved? within the Sky Broadband help forums, part of the Sky Broadband help and support category; Hi Gymno DLM , Noise Margin etc has nothing to do with ping 'jitter' - 6db or 7db its high ...

    1. #71
      snadge's Avatar
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      Re: Upstream attenuation halved?

      Hi Gymno

      DLM, Noise Margin etc has nothing to do with ping 'jitter' - 6db or 7db its high enough for a nice stable connection..especially on your short line - pings will be same regardless of Noise Margin (unless it dropped to 0db and below and caused instabilitys), if your getting 27ms then you will probably be on standard profile (not gamer) which has Interleave Depth of 64, if you were on Gamer Profile you would have a 8ms delay set (unsure of what Interleave Depth is set to get 8ms delays) which would give you sub-20ms pings on your connection...I think anyway.

      jitter (on pingtest) is the difference between lowest and highest ping - you will ALWAYS get some jitter, its unrealistic to expect the exact same ping 24-7 (even if you get it most the time) for that too happen there would have to be no other traffic at all on the internet - ive noticed with sky I get anywhere from 2-6ms jitter and 31-33ms result...this is good and normal, with o2 I used to get 29ms ping and 1-2ms jitter so slightly better but nothing to write home about.

      20Mb and 'Gamer Profile' are two seperate things...if you ask for 20Mb Gamer Profile they will enable both, your already on the 20Mb profile because you have 19,999k sync but as I already said I dont think your on the gamer profile (emphasis on the word 'think').

      DLM can now set 3db Noise Margins if line supports it, theres talk of it setting Noise Margin anywhere between 3-7db..I would like proof of that, one could always have 1db of noise on the line that means when it re-syncs with 7db TNM it displays 6db...get my drift? OR it can work the way I explained a few weeks back, where you would still get 7db but just slightly lower speed because of that 1db noise - ive noticed with mine it seems to go back to 7db from where its at and adjust the speed to match so it does have strength that theory.. right now ive managed to get it when the line was extremely quiet and I have a 17.22Mb sync, the Noise Margin never hits 7db hehe always 6.2-6.8, so if i reboot now I will lose a few hundred kps but have 7db Noise Margin...so in that respect it would seem the way i explained weeks ago sounds about right, which would mean if you reboot too 6db every time then 6db has been 'set', Ive been told reps can not set any noise margins, so it must be DLM.
      - Hardware - Netgear DG834Nv1
      - Line Attenuation - 27.5db
      - Sync Rate - 17,600k
      - Noise Margin - 7db
      - Latency - 28ms


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    3. #72
      gymno's Avatar
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      Re: Upstream attenuation halved?

      I'm currently on the 20mb service profile with 8ms delays, which is effectively the same as being on the gamer profile.
      I believe any delay can be applied to any service profile, such as 8, 16, 32ms. That's what cst told me anyway.

      RE: pings. i'm pretty sure that to be getting the high 23ms - low 25ms that i do, i couldn't possibly be on anything other than 8ms delays.

      All i know for sure is that in the past, i've been on both the 20mb service profile & the 20mb gamer profile with a target nm of 7db & had slightly less jitter than i do now.

      There is a forum member that tweaks their nm all the way up to 12db, in order to achieve virtually no jitter & a ping of 5ms. On adsl!
      Mind you, raising the nm in their case does trim off a fair bit if speed, so maybe that's where the latency improvements come from.

      At the end of the day, i'm just chuffed that i can get stuck into some gaming again & if my attempts to get that last 1% improvement fails, it's no big deal

      *edit Sorry, that member gets pings of 11ms.
      Last edited by gymno; 04-10-12 at 03:33 AM.

    4. #73
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      Re: Upstream attenuation halved?

      I've just been put on the gamer profile.

      PING 212.58.241.131 (212.58.241.131): 56 data bytes
      56 bytes from 212.58.241.131: icmp_seq=0 ttl=247 time=24.3 ms
      56 bytes from 212.58.241.131: icmp_seq=1 ttl=247 time=24.8 ms
      56 bytes from 212.58.241.131: icmp_seq=2 ttl=247 time=24.6 ms
      56 bytes from 212.58.241.131: icmp_seq=3 ttl=247 time=24.8 ms

      ADSL Link Downstream Upstream
      Connection Speed 19884*kbps 1168*kbps
      Line Attenuation 22.5*dB 5.7*dB
      Noise Margin 7.1*dB 6.3*dB

      Still have the crazy upstream attenuation & i've lost 115kb speed (for now) but the pings are rock solid.

      I also mentioned my first years experience with sky broadband & they've given me 6 months half price line rental as a gesture of goodwill.

      Result

    5. #74
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      Re: Upstream attenuation halved?

      Hi Gymno, glad your all sorted, keep eye on line attenuation.

      Im on the 20Mb service and i dont get 24ms delays, 20Mb and Gaming Profile are definitely two separate entity's.

      if 8ms delay results in 24ms then it is probably an interleave depth of 32, because Iam on 64 and get 32ms (this could possibly mean 16ms is what you would typically get with no interleaving at all... 8ms+16ms=24ms (8ms = 32 depth) 16ms+16ms=32ms (16ms = 64 depth)...just theory at this stage

      the first tier reps can not add any delay they like..only gamer, or, DLM sets it when line is profiled - a Network Team Operative will be able to set anything he/she likes possibly as he/she has full access to ALL the values...standard reps do not..as far as im aware anyway.

      I think youve been misled about the Noise Margin relation with Pings/Jitter - the reason this person probably sets high SNRM is because he has a noisey line but wants to game and low SNRM and Low Interleave Depth causes lots of errors for him/her on that line (because interleave helps protect against errors) - so too keep low Interleave Depth you could move your signal further away from the noise via raising the SNRM, I can only speculate as to why that person has done that or why you think higher SNRM means lower pings or less jitter, but as far as I'm aware it doesn't have any relation to it in that manner.

      JITTER - switch latency
      what causes differing pings (jitter) is traffic and switch latency at any given time, if traffic is low and ISAM/Switches/Routers en-route to destination are not busy then there will be less jitter between repeated pings - if network is busy with lots of traffic etc then there will be more jitter, this is because the latency and jitter is result of how quick the switch/router can handle and pass on your data ...and traffic load varies from second to second.

      PING - error correction values
      The size of your ping depends not only on traffic as mentioned above, but also the error correction settings such as Impulse Noise Protection (INP) and Interleaving Depth, the higher these values are set, the longer the delay/latency and thus ping is "bigger" (also sync speed is severely affected by these too, especially INP)- on sky connections starting from low speed profiles the INP and ID are set high because longer lines tend to be noisier so need more error correction, as DLM goes up through the profiles it reduces the values on each and ping comes down (and why users ping gets quicker as DLM 10 day training takes them up through the profiles) , max is INP=2 and ID=512 and you would have quite high pings and low sync rate, lowest (on sky) is INP=1 and ID=32 (I think anyway, from what I speculated earlier) which would give you the gamer profile with 8ms delays... - INP is usually set 0, 0.5, 1, or 2 , but some hardware (such as Broadcom chipsets) can now set fraction values in between (such as 1.1) by adjusting the amount of symbols in each codeword.

      If you read the entire error correction and interleaving section on the afore mentioned page it will basically explain the jist of it.

      if you really wanted to try it you could, just buy a router with a Broadcom chipset thats not locked to ISP firmware, you can use tools to tweak the SNRM yourself, you can raise it to as high as 21db (300%) using DMT Tool on routers such as most Netgear's and a few other routers... I am waiting for delivery of an FTTC BT openreach modem i got for 10 on ebay... im going to pair it with my Sky Hub.. its a Huawei HG612 with latest broadcom 6368 chipset, reason is so I (hopefully) get the high speed such as I get from Broadcom 6362/6361 chipsets on the sky routers AND can tweak the SNRM (to get more speed) & get advanced stats...as you cant do this on 2504N or Sky-Hub, I will be using the HG612 as modem connected to the sky-hub which I will be using for its Wi-Fi, This is because the Netgears I have use older Broadcom chipset such as 6348 and 6358 and actually sync about 1.5Mb - 2Mb lower than the sky routers which use newer broadcom chipsets such as 6361 and 6362 and reducing the SNRM on the Netgears only matches the sky routers speed 17.2Mb (or slightly bests it) with 4db Noise Margin...so not worth the slightly increased FEC count.. so I thought if I could get a newer broadcom chipset modem/router that I could TWEAK then I should be able to get 17Mb sync but also tweak it to 19Mb...big difference!

      either way it looks like your all sorted now mate - be interesting to see if that Line Attenuation mends itself..
      Last edited by snadge; 06-10-12 at 01:02 AM.
      - Hardware - Netgear DG834Nv1
      - Line Attenuation - 27.5db
      - Sync Rate - 17,600k
      - Noise Margin - 7db
      - Latency - 28ms

    6. #75
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      Re: Upstream attenuation halved?

      Quote Originally Posted by snadge View Post
      Im on the 20Mb service and i dont get 24ms delays, 20Mb and Gaming Profile are definitely two separate entity's.
      No, they are not. The settings from 20mbps service profile and 20mbps gaming profile are the same. 20000/1216 bit rates, 8ms delays with 1symbol INP.

      Quote Originally Posted by snadge View Post
      the first tier reps can not add any delay they like..only gamer
      Incorrect. Only a select few tier 1 have access to manually apply profile settings. Those who do, can change to whatever profile they want out of the pre-selected ones on ISAMs. All done through the same system that CST use, no different.

      Also, for the record, INP can be set from 0-4 symbols.

      I think we've been through this before, Snadge. Let's make sure you put disclaimers where you're making up theories and/or just doing guess work from things that you've read. This site doesn't have a silly little Kudos system to make people look important - people just want to hear correct things on this site.

    7. #76
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      Re: Upstream attenuation halved?

      @ USER05

      GAMING PROFILE:
      - I was under the impression Gaming Profile (8ms delays) can be applied to any profile, thats what I meant by it being two seperate entity's - I got the impression that the OP thought they were one and the same thing in that 8ms delays couldnt be applied to other profiles - ive seen plenty of users on speeds sub 10Mb never mind sub 20Mb having 8ms delay applied - if this simply puts them on the 20Mb profile (even though their line can only support, for e.g. 6Mb) to give them the 8ms delays then fair do's - It seemed to me that the 6Mb profile was kept but 8ms delays applied.

      INTERLEAVING DEPTH:
      as for reps changing the delay (not profile, like you mention), the OP said "I believe any delay can be applied to any service profile, such as 8, 16, 32ms" (we are on about the Interleaving Depth, not profile, hence the word 'delay'...I meant the first tier reps can not manually set any interleaving depth they like on any given profile..) - are you saying they can change Interleaving Depth to ANY value they like upon user request? because thats what Iam on about and I was told that this is not true by a few sources and its typical of ISPs to refuse this request (apart from ISPs that have the Fastpath option where Interleave can be ON or OFF), perhaps I will call sky and ask them if I can have my Interleave Depth set to my preferred value then if thats the case...lol.

      DISCLAIMERS:
      I do put in disclaimers when Iam not certain .. such as (e.g. from my post above):-
      just theory at this stage
      standard reps do not..as far as im aware anyway.
      I think anyway, from what I speculated earlier

      ...but sometimes I may forget as Iam typing it out, for that I can only apologize for being human and making a mistake.

      KUDOS:
      as for KUDOS I dont give a hoots about kudos, I only put that in my signature on sky-forums because I saw others doing it and I dont know how it makes me/you/anyone look "important" I dont think many people click on users names and then peruse their profiles too see "how many kudos" they have lol - i couldnt give a cr*p about it and the fact that you think I do just makes me laugh... in fact, if it floats your boat I will remove it because it means N-O-T-H-I-N-G to me..

      you can go through everything I post with your fine 'I was a sky rep ...3 years ago' tooth comb and bend & twist words as much as you like (as with the 'interleaving depth' example above...which suddenly became 'profiles'..lol) - I dont mind, your just a rude bully...keep up the good work!

      iwnte
      - Hardware - Netgear DG834Nv1
      - Line Attenuation - 27.5db
      - Sync Rate - 17,600k
      - Noise Margin - 7db
      - Latency - 28ms

    8. #77
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      Re: Upstream attenuation halved?

      First off, I don't want to ruin the OP's thread with replying to and fro, I've made my point and I'll simply reiterate again as my last response to you.

      Quote Originally Posted by snadge View Post
      ive seen plenty of users
      That's my point. This is always your response - you have 'seen' plenty of other users or you have read a bunch on kitz or wherever else on-line. It's all theory, so let's not confuse matters with theory when I've already illustrated the difference between service and gamer profiles previously. I could explain why Sky can't change simply delays on ISAMs without changing the profile, but I'll not waste my time so that you can flog off the knowledge as your own. However, rest assured that I am correct.

      Quote Originally Posted by snadge View Post
      are you saying they can change Interleaving Depth to ANY value they like upon user request? because thats what Iam on about and I was told that this is not true by a few sources and its typical of ISPs to refuse this request (apart from ISPs that have the Fastpath option where Interleave can be ON or OFF), perhaps I will call sky and ask them if I can have my Interleave Depth set to my preferred value then if thats the case...lol.
      When did I mention the term 'interleaving depth'? I quoted, and was referring to, (max) delays.

      Quote Originally Posted by snadge View Post
      in fact, if it floats your boat I will remove it because it means N-O-T-H-I-N-G to me..
      Calm down - I haven't visited the official Sky forum in a long time as it's a joke of a support site. You can do whatever you like.

      Quote Originally Posted by snadge View Post
      you can go through everything I post with your fine 'I was a sky rep ...3 years ago' tooth comb and bend & twist words as much as you like (as with the 'interleaving depth' example above...which suddenly became 'profiles'..lol) - I dont mind, your just a rude bully...keep up the good work!
      I suggest you don't take things so personally. If you're going to try and be the source of Sky knowledge, then I strongly advise you stick to things that you know, not things that you simply surmise. If you wish to continue flailing incorrect statements around about what advisors can do over the phone, then I'm sure the customers on the Sky forum will listen.

    9. #78
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      Re: Upstream attenuation halved?

      Just thought i'd wrap this up.

      It's been 10 days since the new exchange equipment went live & for 10 days my line has been great.
      Er, that is apart from a 5 hour exchange outage yesterday, which had me wondering if i'm just not supposed to have sky broadband, but everything is back to normal now.

      Pings are exactly how they always used to be at 24-25ms, as is the speed at 19999/1175kbps.

      Upstream attenuation is still a random affair, so will have to remain a mystery to me. It doesn't seem to have any affect on line performance.

      Most importantly though, i'm able to shoot people from all around the world in the evenings again...

      And in the head / chest / goolies etc
      NewsreadeR and andrewjr like this.

    10. #79
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      Re: Upstream attenuation halved?

      here is my thoughts as the thread is a mess.

      dont keep rebooting your router, it was clearly not a sync problem and on a service that uses DLM was a bad idea. On adsl fluctuating snrm happens unless its a very good quality line. The fluctuating reported attenuation was probably an issue with router or exchange equipment but cosmetic only as physical attenuation wouldnt have been changing.

      It looked obvious to me early on in this thread it was exchange congestion whether it backhaul or something else and I cant believe the run around you went through to get it fixed, and yes with this sort of problem pings are almost useless, you really should have done traceroute's.

      The good news is at least sky fixed it fairly quickly after they finally did their proper investigation.

     

     
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