Your forum username:
Do you already have an account?
Forgot your password?
  • Log in or Sign up


    Welcome to Sky User - The Unofficial Support Forum for everything Sky! - Proudly helping over 65k members.


    Advertisement

    Page 5 of 8 FirstFirst ... 34567 ... LastLast
    Results 41 to 50 of 79
    Like Tree4Likes

    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 the ISAM is loaded up with 'Line-Cards' - this is what you and X others are plugged into ...

    1. #41
      snadge's Avatar
      snadge is offline Sky User Member
      Exchange: Blaydon
      Broadband ISP: SKY Broadband Unlimited
      Router: Sagem F@ST 2504n
      Sky TV: Sky+ HD
      Join Date
      Jul 2008
      Posts
      320
      Thanks
      8
      Thanked 6 Times in 6 Posts

      Re: Upstream attenuation halved?

      Hi Gymno

      the ISAM is loaded up with 'Line-Cards' - this is what you and X others are plugged into (48 users per card I think?) , I dunno if the Line cards themselves get overloaded or not, or if the ISAM itself becomes over-loaded, if I had to guess I would say that BOTH can be overloaded if all available ports/slots where in use beyond average/expected consumption

      for e.g. they probably dont expect every port on every line card to be in use at the same time, this hardware is probably designed for heavy use but some latency delay must be expected when heavy usage occurs (and this is probably in all ISPs T&C's, its in sky's)

      I was told the ISAM in my exchange was "over-loaded" running at 97.5% capacity and would take 6 weeks to sort out, at that time speed was fine but ping was a little iffy like yours, so it seem that you must be able to 'over-load' them by putting into too many Line-Cards in ratio to the usage across them.

      I can only speculate as I do not know, I could ask someone I know works at Alcatel-Lucent (Sky's ISAM manufacturer) but I dont if he would be able to help much.

      what happens with a Lift & Shift is that your remotely changed to a different port , then an engineer goes in and jumpers the wires to divert your signal via the new port

      just keep pushing mate, you will get it sorted in the end
      - Hardware - Netgear DG834Nv1
      - Line Attenuation - 27.5db
      - Sync Rate - 17,600k
      - Noise Margin - 7db
      - Latency - 28ms


    2. Advertisement
    3. #42
      gymno's Avatar
      gymno Guest
      Exchange:
      Broadband ISP:
      Router:
      Sky TV:

      Re: Upstream attenuation halved?

      Wan uptime is 63hrs so looks like dlm has finished.

      ADSL Link Downstream Upstream
      Connection Speed 19998*kbps 1172*kbps
      Line Attenuation 22.5*dB 14.2*dB
      Noise Margin 5.9*dB 9.6*dB

      Bit strange it's used a 6db noise margin when normally i'd get full speeds with a margin of up to 7.6db.
      Maybe a reboot will change it as it's literally been stuck on 5.9db for those 63hrs.

      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=24.1 ms
      56 bytes from 212.58.241.131: icmp_seq=2 ttl=247 time=24.2 ms
      56 bytes from 212.58.241.131: icmp_seq=3 ttl=247 time=24.4 ms

      The last crazy pings i had were on wednesday evening, so i'm just crossing my fingers it isn't congestion.
      Won't be holding my breath though.

    4. #43
      snadge's Avatar
      snadge is offline Sky User Member
      Exchange: Blaydon
      Broadband ISP: SKY Broadband Unlimited
      Router: Sagem F@ST 2504n
      Sky TV: Sky+ HD
      Join Date
      Jul 2008
      Posts
      320
      Thanks
      8
      Thanked 6 Times in 6 Posts

      Re: Upstream attenuation halved?

      upstream attenuation looks ok too - see if that stays around about that figure while the pings remain low - if so it shows they were related

      also, if you reboot now at 5.9 theres a good chance you will LOSE speed, your 22db Atten is the border where anything higher and you get less than 20,000k (on average) - but it depends on the quality of your line and if the ISAM can/will supply more power to the tones if needed - in most scenarios when the noise margin is lower than the target margin its because there is more noise on the line since last re-sync - so re-sync'ing now resets the SNRM back to 7db which means it has to LOSE speed to do so.. same is true for opposite, if Noise Margin is HIGHER than the target margin then re-syncing will GAIN speed

      the way I try to explain the whole SYNC, MARGIN and NOISE thing is by using an anagram of beach (speed), shoreline (noise) and a log (margin) sitting between the cliffs and shore-line - the shoreline is the noise, imagine a log is 6 meters from the shore line (6db margin) when noise increases the shore-line comes in and gets closer to the log (e.g. now 0db Noise Margin) because the router no longer hears the exchange because of the noise it drops the connection and causes a re-sync, this resets the margin (log) back to 6db (6 meters from the shore-line) - but in doing so moves the log closer to the cliffs (which cant be moved) and so less speed can get through (between the log and the cliffs) because theres less room - now when the noise reduces the shore-line goes out, the noise-margin may be much higher than even the target margin such as 9db-12db (9-12meters) so when you re-sync the router it moves the log closer in too the shore-line (back to 6db / 6 meters) and therefore more speed can get through between the log and the cliffs.... that explanation could be made better lol...but its quite clear on helping understand how it works

      its normal for noise margin too fluctuate between 5-8db as noise amounts vary throughout the day

      some connections use SRA (Seamless Rate Adaption) whereby if the Noise Margin is slowly getting less and less, then SRA may recognize this and dynamically reduce the sync-rate and pop the noise margin back up without causing a re-sync - sky use SRA ..apparantley
      - Hardware - Netgear DG834Nv1
      - Line Attenuation - 27.5db
      - Sync Rate - 17,600k
      - Noise Margin - 7db
      - Latency - 28ms

    5. #44
      Shonk's Avatar
      Shonk is offline Sky User Member
      Exchange:
      Broadband ISP: Sky Fibre Unlimited Pro
      Router: Asus RT-AC88U
      Sky TV: Sky+ HD
      Join Date
      Mar 2010
      Posts
      1,460
      Thanks
      7
      Thanked 118 Times in 113 Posts

      Re: Upstream attenuation halved?

      I wouldnt say its normal for a line to fluctuate but it is common

      mine sits like below 24/7

      Elapsed Time 0 day 19 hr 20 min 4 sec
      SNR Margin(Upstream) 9.0 dB
      SNR Margin(Downstream) 12.45 dB
      Line Attenuation(Upstream) 6.0 dB
      Line Attenuation(Downstream) 18.5 dB

      filters play a large roll in fluctuations

      I had an nte2000 for 18 months and it was very good and would never fluctuate more than 0.5db
      and before that i used the sky filters for a few days and they fluctuated around 2db max
      I recently changed to a bt vdsl faceplate and i get 0 fluctiations now

      not all cases will be the filter though ofc

    6. #45
      snadge's Avatar
      snadge is offline Sky User Member
      Exchange: Blaydon
      Broadband ISP: SKY Broadband Unlimited
      Router: Sagem F@ST 2504n
      Sky TV: Sky+ HD
      Join Date
      Jul 2008
      Posts
      320
      Thanks
      8
      Thanked 6 Times in 6 Posts

      Re: Upstream attenuation halved?

      Hi Shonk

      hmm, I would definitely say its normal for a xDSL line's noise margin to fluctuate throughout the day/evening, but if it doesn't fluctuate it doesn't means somethings wrong, just means you have a good line. just about all telephone lines are bounded together in bundles of 10's, 100's and in some cases 1000's causing plenty of cross-talk at various amounts at various times of the day - especially in evenings, with some lines over-head exposed to natural radiation (like radio waves) and possible customers internal noise, its 'expected' to have fluctuating Noise Margins as the noise varies, I would certainly say its not something that 'shouldnt' be happening.

      I would say the reason yours sits like that 24-7 is because it is probably a very good line , quite short in length (about 1300m) and may not be bundled with (or adjacent too) many 'busy/active' lines, shorter lines are easier and better to manage than longer ones,the longer the line, the more fluctuations your likely too have.

      As far as I'm aware filters are simply a low pass filter on the phone output and no filter on the modem output (so the modem gets both phone and broadband signal) thats what I was taught anyway, because a DSL modem always has a built-in high-pass filter, so bearing that in mind the modem/router would/should get the same signal regardless of filter - some filters may have both low pass (voice) & high pass (modem) filters built in, in which case a poor/faulty high-pass filter may have some effect on the noise conditions, one way to be able to test this is by rigging the phone up into the modem port and seeing if you can use the phone - if not then the filter does indeed have a high pass filter built in, if you can use the phone in that port then it does not, use an ADSL cable too hook up the phone 'in' to the modem 'out' on the filter - I will try this tomorrow with various filters and my faceplate as I am curious now because I have often wondered about this.

      I currently have a 26-27db Line Attenuation and the Noise Margin fluctuates between 6.1db and 7.6db (7db the default target SNRM) so I get 1.4db variance, I am using an NTE-2000 filtered faceplate - I too also have a BT VDSL faceplate (SSFP) but its at my Dads, I will ask him to bring it back over when he is next down and I will run some tests and see if it makes any difference in fluctuations with mine, but I get same variance with the NTE-2000 as I do with Sky's Filters...its usually down to 6.1db in evening and back up to 7-7.5db morning/afternoon, I usually consider it an 'issue' if noise margin is dropping to 3-4db or less - this is because once the margin gets below 3db on mine the Corrected and Un-Corrected RS code word count increases a lot which shows the signal is getting a lot of impulse noise as its closer to the noise, CRC's occur and re-transmits take place thus slowing (or even pausing) some of your web page loads.
      - Hardware - Netgear DG834Nv1
      - Line Attenuation - 27.5db
      - Sync Rate - 17,600k
      - Noise Margin - 7db
      - Latency - 28ms

    7. #46
      gymno's Avatar
      gymno Guest
      Exchange:
      Broadband ISP:
      Router:
      Sky TV:

      Re: Upstream attenuation halved?

      Just tried a reboot & it seems dlm has stickied my noise margin at 6db

      ADSL Link Downstream Upstream
      Connection Speed 19997*kbps 1168*kbps
      Line Attenuation 23.0*dB 12.8*dB
      Noise Margin 6.2*dB 8.8*dB

      Random upstream attenuation again.

      @snadge: I know what you're saying about the relationship between noise margin & speed.
      That's the orthodox way lines work... I just wish mine was the same.
      I rebooted once with 6.1db noise & it resync'd at 7.4db with a 4kb gain? (see 1st post of this thread)
      Last edited by gymno; 11-09-12 at 05:53 PM. Reason: re-ordered sentences, to be clearer

    8. #47
      gymno's Avatar
      gymno Guest
      Exchange:
      Broadband ISP:
      Router:
      Sky TV:

      Re: Upstream attenuation halved?

      Tried another reboot this morning:

      ADSL Link Downstream Upstream
      Connection Speed 19998*kbps 1172*kbps
      Line Attenuation 23.0*dB 10.0*dB <<<
      Noise Margin 6.2*dB 9.1*dB

      Hooked up a new (well, virtually unused) 2504n, psu & adsl cable:

      ADSL Link Downstream Upstream
      Connection Speed 19992*kbps 1172*kbps
      Line Attenuation 23.0*dB 14.3*dB <<<
      Noise Margin 6.1*dB 9.4*dB

      Rebooted that after setting up dmz & got exactly the same stats.

      Hooked up old router, psu & adsl cable again:

      ADSL Link Downstream Upstream
      Connection Speed 19992*kbps 1172*kbps
      Line Attenuation 23.0*dB 11.8*dB <<<
      Noise Margin 6.0*dB 9.6*dB

      Hhmmm.

    9. #48
      Scubbie's Avatar
      Scubbie is online now Sky User Moderator
      Exchange: 02392
      Broadband ISP: Sky Fibre Unlimited
      Router: Sky Q Hub ER110
      Sky TV: Sky+HD box
      Join Date
      Mar 2010
      Location
      Near Portsmouth
      Posts
      27,895
      Thanks
      810
      Thanked 2,194 Times in 2,064 Posts

      Re: Upstream attenuation halved?

      You are on the 20mb/1175kb profile. Your connection probably won't support anything faster.

      All should be fine now.

      Sky Fibre Unlimited Pro: Connected at 80,000 kbps / 20,000 kbps
      Previous ADSL2+ Speed 19999 kbps 1153 kbps, Line Attenuation 17.5 db 6.9 db, Noise Margin 7.5 dB 8.7 dB
      Speedtest: 17.15MB/s 0.97Mb/s Ping 31 ms

    10. #49
      gymno's Avatar
      gymno Guest
      Exchange:
      Broadband ISP:
      Router:
      Sky TV:

      Re: Upstream attenuation halved?

      I'm not looking for any more speed.
      I've always been extremely happy with that side of things & feel quile lucky to have always had the full 20mb.

      What i'm querying is why dlm has used a target noise margin of 6db, when my line has always achieved those speeds with a target noise margin of 7db (usually varying from 7.5db in the morning to 7db in the evening).

      Also what the random upstream attenuation is all about, which appears to not be happening with the new equipment.

      But here's the big one.
      The whole reason i have broadband is for online gaming, but my pings keep going sky high.
      Mon - thurs 8:30 - 10:30pm, 24 - 120ms
      Fri,sat & sun 7 - 11:30pm, 24 - 120ms

      It's not every day, but inevitably it's whenever i fancy a game.
      I'm just posting everything i think may be relevant in an effort to get to the bottom of it.

      I seriously don't want to leave sky, but not being able to game properly is just about the only thing that would force me to do so

    11. #50
      Scubbie's Avatar
      Scubbie is online now Sky User Moderator
      Exchange: 02392
      Broadband ISP: Sky Fibre Unlimited
      Router: Sky Q Hub ER110
      Sky TV: Sky+HD box
      Join Date
      Mar 2010
      Location
      Near Portsmouth
      Posts
      27,895
      Thanks
      810
      Thanked 2,194 Times in 2,064 Posts

      Re: Upstream attenuation halved?

      There is a possibility that something has affected your line and DLN has managed to correct for that.

      I used to get the full 20mb too on a noise margin of 7dB. Sadly something has happened with mine and I now get ~19,500kbps. With a non-sky router I can tweak the noise margin and get the full 20mb back.

      Sky Fibre Unlimited Pro: Connected at 80,000 kbps / 20,000 kbps
      Previous ADSL2+ Speed 19999 kbps 1153 kbps, Line Attenuation 17.5 db 6.9 db, Noise Margin 7.5 dB 8.7 dB
      Speedtest: 17.15MB/s 0.97Mb/s Ping 31 ms

     

     
    Page 5 of 8 FirstFirst ... 34567 ... LastLast

    Tags for this Thread

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •  
    SkyUser - Copyright © 2006-2017. SatDish and NewsreadeR | SkyUser is in no way affiliated with Sky Broadband / BSkyB
    RIPA NOTICE: NO CONSENT IS GIVEN FOR INTERCEPTION OF PAGE TRANSMISSION