Erratic upstream attenuation

[Khristian]

I have a quick query for the more experienced users, I recently had Sky broadband installed at a new property, originally I was advised (by Sky) I would get between 7-14 Mbps, BT were saying 10-19.5 Mbps (Typically 17 Mbps). So of course I'm happy that I'm receiving 21 Mbps / 1.2 Mbps.

However I have noticed that when the line re-syncs the upstream attenuation can sometimes change wildly.

Examples:

Wed 07 Nov 2012 *08:00 Rx-Noise=3.2 Tx-Noise=9.8 Rx-Sync=21021 Tx-Sync=1193 DownAtt=13.0 UpAtt=8.5
Thu 08 Nov 2012 *00:58 Rx-Noise=3.1 Tx-Noise=7.0 Rx-Sync=21022 Tx-Sync=1175 DownAtt=13.0 UpAtt=5.7
Thu 08 Nov 2012 *01:06 Rx-Noise=3.1 Tx-Noise=7.1 Rx-Sync=21021 Tx-Sync=1175 DownAtt=13.0 UpAtt=4.1
Thu 08 Nov 2012 *09:27 Rx-Noise=3.1 Tx-Noise=7.2 Rx-Sync=21021 Tx-Sync=1179 DownAtt=13.0 UpAtt=7.4
Thu 08 Nov 2012 *12:07 Rx-Noise=3.1 Tx-Noise=9.5 Rx-Sync=21021 Tx-Sync=1161 DownAtt=12.5 UpAtt=8.4 ***
Thu 08 Nov 2012 *12:15 Rx-Noise=3.1 Tx-Noise=7.1 Rx-Sync=21021 Tx-Sync=1157 DownAtt=12.5 UpAtt=6.1 ***
Thu 08 Nov 2012 *12:45 Rx-Noise=3.1 Tx-Noise=0.2 Rx-Sync=21018 Tx-Sync=1157 DownAtt=12.5 UpAtt=6.0 ***
Thu 08 Nov 2012 *12:50 Rx-Noise=3.1 Tx-Noise=100.1 Rx-Sync=21021 Tx-Sync=1179 DownAtt=13.0 UpAtt=8.5
Thu 08 Nov 2012 *13:35 Rx-Noise=3.1 Tx-Noise=9.6 Rx-Sync=21020 Tx-Sync=1186 DownAtt=13.0 UpAtt=8.5
Thu 08 Nov 2012 *13:40 Rx-Noise=3.1 Tx-Noise=9.9 Rx-Sync=21018 Tx-Sync=1182 DownAtt=13.0 UpAtt=4.3
Thu 08 Nov 2012 *15:46 Rx-Noise=3.1 Tx-Noise=7.1 Rx-Sync=21022 Tx-Sync=1179 DownAtt=13.0 UpAtt=8.5

*** = Using Sky's F@st2504n, all other times using Netgear DGND3700v1

There have been other times the Upstream Attenuation has shown as low as 0.2.

So I've been battling for a week with 'First Line' to pass it to CST to book an engineer, it's now passed to CST, just waiting on if a BTO engineer will be sent out.

I'm just wondering if anyone else has experienced this, and if so was it a line issue or something else?

Fortunately I'm one of those customers who CST have previously agreed can use my own equipment providing if there is a fault I can also demonstrate this using the Sky equipment (hence the *** marked tests). I have also of course checked all wiring and ran tests using the test socket, different cables, filters (including an NTE2000 and vDSL faceplate (as now supplied by BT).

For those who will request it, full current stats from telnet are:


adsl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 1247 Kbps, Downstream rate = 23724 Kbps
Bearer: 0, Upstream rate = 1189 Kbps, Downstream rate = 20974 Kbps

Link Power State: L0
Mode: ADSL2+
TPS-TC: ATM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 3.1 8.9
Attn(dB): 13.0 7.7
Pwr(dBm): 18.5 12.1

ADSL2 framing
Bearer 0
MSGc: 59 14
B: 216 17
M: 1 8
T: 3 7
R: 16 14
S: 0.3306 3.8419
L: 5639 329
D: 96 8

Counters
Bearer 0
SF: 122125 117050
SFErr: 0 0
RS: 23814344 2047647
RSCorr: 448 0
RSUnCorr: 0 0

Bearer 0
HEC: 0 0
OCD: 0 0
LCD: 0 0
Total Cells: 97354225 5522655
Data Cells: 422006 101086
Drop Cells: 0
Bit Errors: 0 0

ES: 0 0
SES: 0 0
UAS: 0 0
AS: 1969

Bearer 0
INP: 1.00 1.00
INPRein: 0.00 0.00
delay: 7 7
PER: 16.11 16.80
OR: 32.26 9.51

Bitswap: 355/360 314/314

Total time = 32 min 49 sec
FEC: 448 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 2 min 49 sec
FEC: 27 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 157 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 32 min 49 sec
FEC: 448 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Since Link time = 32 min 47 sec
FEC: 448 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
~ #

[gymno]

You're not the only one.

My upstream attenuation sat between 13.9 & 14.3db for about 10 months, before my line developed a fault & i had some work done on it.
Since then, on each resync it can be anywhere between 6 & 14.3db.

From reading the stats in a few other posts, it seems to be happening to several others too.

I first posed the question here: http://www.skyuser.co.uk/forum/sky-b...on-halved.html

I can't say i've come across a satisfactory explanation yet, but the good news is in all cases so far, it's had no effect on line performance at all.

[Isitme]

I think Gymno has the right attitude, if you are not suffering problems, don't worry about it. Apart from that your stats are excellent with no uncorrected errors and a good sync speed. What more can you want

[Shonk]

It could well be power saving features

check the upstream / downstream power level on each sync

mine never changes due to my dslam not having the power save modules installed

One from a few days ago

LocalSNRMargin = 8.35 dB
LocalLineAttn = 18.5 dB
INPup = 0.00
INPdown = 0.00
PMstatus = L0
LocalTxPower = 8.4 dB
LocalFastChannelRxRate = 21950004
LocalFastChannelTxRate = 1216000
RemoteTxPower = 20.3 dB
RemoteLineAttn = 5.5 dB
RemoteSNRMargin = 9.5 dB

My current sync

LocalSNRMargin = 11.55 dB
LocalLineAttn = 18.5 dB
INPup = 0.00
INPdown = 0.00
LocalTxPower = 8.4 dB
LocalFastChannelRxRate = 20251840
LocalFastChannelTxRate = 1216000
RemoteTxPower = 20.3 dB
RemoteLineAttn = 5.5 dB
RemoteSNRMargin = 9.0 dB

[Khristian]

Hi

Cheers for the feedback, I'm inclined to agree after reading around that it's nothing really to worry about as it does not seem to be causing any really high errors.

I've checked a few readings that I had from the router regarding power, these were

Rx-Noise=3.1 Tx-Noise=8.9 Rx-Sync=20974 Tx-Sync=1189 DownAtt=13.0 UpAtt=7.7 DownPwr=18.5 UpPwr=12.1

Rx-Noise=3.2 Tx-Noise=9.9 Rx-Sync=21003 Tx-Sync=1182 DownAtt=13.0 UpAtt=5.2 DownPwr=18.5 UpPwr=12.0

Rx-Noise=3.1 Tx-Noise=7.1 Rx-Sync=21003 Tx-Sync=1189 DownAtt=13.0 UpAtt=2.9 DownPwr=18.4 UpPwr=12.0

Rx-Noise=3.1 Tx-Noise=7.0 Rx-Sync=21021 Tx-Sync=1182 DownAtt=13.0 UpAtt=8.3 DownPwr=18.4 UpPwr=12.0

So it seems the power is staying pretty much stable.

I do just have a couple of other questions, can anyone advise if my current (21/1.3) profile (as per MySky) is equivalent to a 'Gamer' profile? Not that I'm a gamer, but the lower ping times would be useful as I have a couple of VoIP adapters that I frequently use for working from home.

Also, as I'm sure some users will agree the Netgear DGND3700v1 is not exactly the best of routers and has some issues, so I'm not adverse to using the Sky supplied equipment (although the lack of stats is annoying), can anyone advise (in their opinion) if the new SR101 would be better than the f@st2504n? I'm not over fussed about the wireless as I use several Apple Airports around the house.

[Isitme]

I do just have a couple of other questions, can anyone advise if my current (21/1.3) profile (as per MySky) is equivalent to a 'Gamer' profile?

No on the gamer profile you would be on 20/1.3. I doubt if it would improve it much as you will be on a 8 ms delay, same as the gamer. What is your ping time?

From what I have read on the forum the new Hub is not much better, if any than the 2504N.

[Khristian]

Just done a quick ping test from my PC

Pinging BBC - Homepage [212.58.244.68] with 32 bytes of data:
Reply from 212.58.244.68: bytes=32 time=34ms TTL=54
Reply from 212.58.244.68: bytes=32 time=33ms TTL=54
Reply from 212.58.244.68: bytes=32 time=36ms TTL=54
Reply from 212.58.244.68: bytes=32 time=33ms TTL=54

Ping statistics for 212.58.244.68:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 33ms, Maximum = 36ms, Average = 34ms

Test from an iMac and pretty much the same results, so actually not looking too bad although sometimes it does go a bit high but I've been putting that down to it being 'busy' times.

[gymno]

I'm on the 20mb gamer profile.

ADSL Link Downstream Upstream
Connection Speed 19999*kbps 1175*kbps
Line Attenuation 22.5*dB 11.4*dB
Noise Margin 6.9*dB 9.0*dB

PING 212.58.244.68 (212.58.244.68): 56 data bytes
56 bytes from 212.58.244.68: icmp_seq=0 ttl=56 time=24.5 ms
56 bytes from 212.58.244.68: icmp_seq=1 ttl=56 time=24.9 ms
56 bytes from 212.58.244.68: icmp_seq=2 ttl=56 time=24.4 ms
56 bytes from 212.58.244.68: icmp_seq=3 ttl=56 time=24.4 ms

I only own a ps3 so can't do proper cmd prompts.
The ping test above was done using the tool on the diagnostics page of my router & i'm told the icmp that it uses gives slightly worse results than a cmd prompt would.

It may be that your max delays are set to 16ms & not 8ms, which is basically all the gamer profile does.

Other forum members know a lot more about this than i do though, so i'd hang on for another opinion.

[Shonk]

D: 96 8
INP: 1.00 1.00
delay: 7 7

You are on better than the gamer profile can provide

you are on 7ms downstream delay 7ms upstream delay
Max interleave depth 96 downstream
Max interleave depth 8 upstream

if sky set you to the gamer profile you would get 8 8
320 8


Regards to your ping first you have to account for your route into london
second you have to add a few ms for wireless

Wired
Pinging 212.58.244.68 with 32 bytes of data:
Reply from 212.58.244.68: bytes=32 time=11ms TTL=55
Reply from 212.58.244.68: bytes=32 time=11ms TTL=55
Reply from 212.58.244.68: bytes=32 time=11ms TTL=55
Reply from 212.58.244.68: bytes=32 time=11ms TTL=55

Ping statistics for 212.58.244.68:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 11ms, Maximum = 11ms, Average = 11ms

Wireless
Pinging 212.58.244.68 with 32 bytes of data:
Reply from 212.58.244.68: bytes=32 time=17ms TTL=55
Reply from 212.58.244.68: bytes=32 time=15ms TTL=55
Reply from 212.58.244.68: bytes=32 time=13ms TTL=55
Reply from 212.58.244.68: bytes=32 time=13ms TTL=55

Ping statistics for 212.58.244.68:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 13ms, Maximum = 17ms, Average = 15ms

[gymno]

ignore