ADSL Experts in here please!

Dr. Z · 05-07-2009, 15:26

Just moved into a new (shared) place and am getting fairly shoddy results on my line here...

Here are the stats that my router has given me, what hope do I have of improving this with better filters / test sockets and things?

Code:

show dsl interface atm0
                ATU-R (DS)                      ATU-C (US)
Modem Status:    Showtime (DMTDSL_SHOWTIME)
DSL Mode:        ITU G.992.1 (G.DMT)
ITU STD NUM:     0x01                            0x01
Vendor ID:       'ALCB'                          'IFTN'
Vendor Specific: 0x0000                          0x7153
Vendor Country:  0x00                            0xB5
Capacity Used:   96%                             96%
Noise Margin:    13.5 dB                         14.0 dB
Output Power:    20.0 dBm                        11.0 dBm
Attenuation:     44.0 dB                         26.5 dB
Defect Status:   None                            None
Last Fail Code:  None
Selftest Result: 0x00
Subfunction:     0x15
Interrupts:      650 (1 spurious)
Activations:     2
Init FW:         embedded
Operartion FW:   embedded
SW Version:      3.919
FW Version:      0x1A04

                 Interleave             Fast    Interleave              Fast
Speed (kbps):          3840                0           128                 0
Reed-Solomon EC:      48019                0            16                18
CRC Errors:            1015                0            82                 2
Header Errors:          992                0            27                12
Bit Errors:               0                0
BER Valid sec:            0                0
BER Invalid sec:          0                0

LOM Monitoring : Disabled

DMT Bits Per Bin
00: 0 0 0 0 0 0 0 3 4 4 4 4 4 3 3 3
10: 3 3 2 2 2 2 2 2 2 0 2 0 0 0 0 0
20: 0 0 0 0 0 0 5 5 6 7 7 7 8 8 8 8
30: 8 8 8 8 9 9 9 8 8 8 8 8 8 8 8 2
40: 9 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8
50: 8 8 8 8 7 8 8 8 8 8 8 8 8 8 8 8
60: 8 8 8 7 7 7 7 7 7 7 7 7 7 7 7 7
70: 7 7 7 7 7 7 7 7 7 7 7 7 7 6 6 7
80: 7 7 7 7 7 6 6 6 6 6 6 6 6 6 6 6
90: 6 6 6 6 6 6 6 6 5 6 6 6 6 6 6 6
A0: 6 5 5 5 5 5 5 4 5 5 5 5 5 5 5 5
B0: 2 5 4 4 4 4 4 4 4 4 4 4 4 5 5 5
C0: 5 4 4 4 4 4 2 4 4 4 3 3 3 3 3 3
D0: 2 0 0 0 0 0 2 2 2 2 2 2 3 3 3 2
E0: 2 3 3 3 3 3 2 2 0 2 2 2 2 2 2 2
F0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Training log buffer capability is not enabled yet.

Thanks!

divine · 05-07-2009, 15:47

44dB attenuation is pretty bad and will most likely be down to line length/condition - you can try better filters etc. but I don't think it will help much.

For comparison:

Link Information

Uptime: 9 days, 17:29:30
DSL Type: G.992.5 annex A
Bandwidth (Up/Down) [kbps/kbps]: 1,230 / 3,826
Output Power (Up/Down) [dBm]: 12.0 / 17.0
Line Attenuation (Up/Down) [dB]: 25.5 / 46.5
SN Margin (Up/Down) [dB]: 6.5 / 8.0

Mark · 05-07-2009, 15:57

Have you tried the usual trick - master socket faceplate off and plugged straight into the test socket with no filters? That'll tell you for sure.

Line stats don't look spectacularly bad, but they are certainly plenty bad enough. If you've got cheapo crap filters (which I would doubt given your background) then by all means change them. Otherwise, probably not a huge amount to be gained.

PS - the high Noise Margin may indicate there is either still some more line training to be done, or that you have sporadic noise on the line, or it may simply be down to the high attenuation. The default target is typically 6.

Aboobie · 05-07-2009, 17:04

Lucky sod... they're not bad, here are mine...

ADSL Link Downstream
Connection Speed 3008 kbp
Line Attenuation 63.0 db
Noise Margin 6.9 db

Dr. Z · 05-07-2009, 17:44

Quote:

Originally Posted by Aboobie

Lucky sod... they're not bad, here are mine...

ADSL Link Downstream
Connection Speed 3008 kbp
Line Attenuation 63.0 db
Noise Margin 6.9 db

Lucky? In the last three years I have gone from a 100Mbps synchronous connection to a 20Mbps async and now down to about 4Mbps?

4Mbps feels utterly dreadful to use in comparison!

divine · 05-07-2009, 17:49

You aren't the only one, though I never had the 20Mb intermediate stage

Mark · 05-07-2009, 17:59

Damn students! Think of us lot that have never had 100Mbps*

* OK, so I had it at work for a while. Think they might be rate-limiting for higher priority stuff now though as I never see that sort of speed.

Dr. Z · 05-07-2009, 20:04

Does ADSL learn? I've moved to the master socket and am getting no difference at all.

divine · 05-07-2009, 20:19

Leave it a week, should have found its limit by then - try not to keep killing the connection as it may get interpreted as instability and the speed reduced.

Burble · 05-07-2009, 22:09

Quote:

Originally Posted by Dr. Z

Does ADSL learn? I've moved to the master socket and am getting no difference at all.

What has your sync rate changed to? Have a read up on BRAS profiles and you'll see why a small increase in sync rate could give you bugger all extra throughput.

If you're finding the link stable ask your ISP to disable interleaving, you should notice lower ping times thanks to the lack of packet chopping, sorting and re-assembling.

What was the uptime of the ATM interface when you took the stats? Quite a few CRC's there.

05-07-2009, 15:47	#2
divine Moonshine Join Date: Sep 2007 Location: Southampton Posts: 3,201	44dB attenuation is pretty bad and will most likely be down to line length/condition - you can try better filters etc. but I don't think it will help much. For comparison: Link Information Uptime: 9 days, 17:29:30 DSL Type: G.992.5 annex A Bandwidth (Up/Down) [kbps/kbps]: 1,230 / 3,826 Output Power (Up/Down) [dBm]: 12.0 / 17.0 Line Attenuation (Up/Down) [dB]: 25.5 / 46.5 SN Margin (Up/Down) [dB]: 6.5 / 8.0 __________________ Last edited by divine; 05-07-2009 at 15:51.

05-07-2009, 15:57	#3
Mark Screaming Orgasm Join Date: Jul 2006 Location: Newbury Posts: 15,194	Have you tried the usual trick - master socket faceplate off and plugged straight into the test socket with no filters? That'll tell you for sure. Line stats don't look spectacularly bad, but they are certainly plenty bad enough. If you've got cheapo crap filters (which I would doubt given your background) then by all means change them. Otherwise, probably not a huge amount to be gained. PS - the high Noise Margin may indicate there is either still some more line training to be done, or that you have sporadic noise on the line, or it may simply be down to the high attenuation. The default target is typically 6. Last edited by Mark; 05-07-2009 at 16:01.

05-07-2009, 17:04	#4
Aboobie Vodka Martini Join Date: Sep 2008 Location: Beverley Posts: 749	Lucky sod... they're not bad, here are mine... ADSL Link Downstream Connection Speed 3008 kbp Line Attenuation 63.0 db Noise Margin 6.9 db __________________

05-07-2009, 17:49	#6
divine Moonshine Join Date: Sep 2007 Location: Southampton Posts: 3,201	You aren't the only one, though I never had the 20Mb intermediate stage __________________

05-07-2009, 20:04	#8
Dr. Z I'm going for a scuttle... Join Date: Jul 2006 Posts: 2,021	Does ADSL learn? I've moved to the master socket and am getting no difference at all. __________________

05-07-2009, 17:59	#7
Mark Screaming Orgasm Join Date: Jul 2006 Location: Newbury Posts: 15,194	Damn students! Think of us lot that have never had 100Mbps* * OK, so I had it at work for a while. Think they might be rate-limiting for higher priority stuff now though as I never see that sort of speed.

05-07-2009, 20:19	#9
divine Moonshine Join Date: Sep 2007 Location: Southampton Posts: 3,201	Leave it a week, should have found its limit by then - try not to keep killing the connection as it may get interpreted as instability and the speed reduced. __________________