Kitz Forum

Broadband Related => Broadband Technology => Topic started by: Weaver on January 14, 2020, 09:09:26 AM

Title: My DSL lines’ latency 47ms
Post by: Weaver on January 14, 2020, 09:09:26 AM

What makes up my latency? I have interleave (hopefully, seriously) set to maximum on the controls at clueless.aa.net.uk but I can’t be sure.

Title: Re: My DSL lines’ latency 47ms
Post by: niemand on January 14, 2020, 03:50:06 PM

Modulation and demodulation of signal at modems and DSLAM(s) - including delay for convolutional interleaving / de-interleaving of symbols prior to modulation.

Travel across the BT Wholesale network to the relevant WBMC gateway where A&A connect to BTW via PPP sessions encapsulated in L2TP. Will be encapsulated and decapsulated multiple times potentially.

Decapsulation from L2TP at the A&A BRAS. I believe it uses LCP echos so nothing to encapsulate in PPP.

From the Highlands to A&A's network you're talking, give or take, 20-25ms across BT Wholesale. The rest will be interleaving, modem related excitement and any very slight delays either side.

psychopomp1 has BT Wholesale FTTP - his trip across the BTW network will be slightly shorter than yours as he's going straight to an NGA headend but you're talking a millisecond or two. The rest is xDSL versus FTTP.

HTH.

Title: Re: My DSL lines’ latency 47ms
Post by: Weaver on January 15, 2020, 06:59:35 PM

So maybe 20ms for interleave / de-interleave ?

Title: Re: My DSL lines’ latency 47ms
Post by: neil on January 16, 2020, 03:29:12 AM

Quote from: Weaver on January 14, 2020, 09:09:26 AM

What makes up my latency? I have interleave (hopefully, seriously) set to maximum on the controls at clueless.aa.net.uk but I can’t be sure.

you cant see in the stats?

Title: Re: My DSL lines’ latency 47ms
Post by: aesmith on January 16, 2020, 03:05:29 PM

Quote from: Weaver on January 15, 2020, 06:59:35 PM

So maybe 20ms for interleave / de-interleave ?

When I was on 20CN meaning interleave could only be "On" or "Off", it added roughly 20ms to the round trip time.  I don't know if that could be derived from the ADSL stats ..

====================================================================================
       ADSL Port Details       Upstream         Downstream
               Line Rate:      0.792 Mbps        4.811 Mbps
    Actual Net Data Rate:      0.780 Mbps        4.779 Mbps
          Trellis Coding:         ON                ON
              SNR Margin:        5.8 dB            5.6 dB
            Actual Delay:          5 ms              8 ms
          Transmit Power:       12.2 dBm          19.3 dBm
           Receive Power:        4.7 dBm           4.7 dBm
              Actual INP:        2.0 symbols       1.0 symbols
       Total Attenuation:       32.0 dB          52.5 dB
Attainable Net Data Rate:      1.244 Mbps        5.132 Mbps
====================================================================================