ADSL Limitation

kdesc · Post by **kdesc** » Tue Apr 19, 2011 4:00 pm

Hi

I have a old ADSL US Robotics modem model USR8550

Recently my connection was upgraded from 600Kbps to 10Mbps.

I'm aware that my modem is limited to 8Mbps download speed because it is old.

The modem status page shows this:

Downstream Fast Channel: 7488 kbps
Upstream Fast Channel: 416 kbps

Looks like the modem is supposed to download at maximum of 7.4Mbps

When I download or do speed tests the maximum speed that I get is 2Mbps.

Is this some misconfiguration in the Internet Provider (even so the status page of the modem shows 7.4Mbps) or the problem is with my modem?

I already have configured my system with TCPOptimizer to 7.5Mbps speed + Optimized, but no luck.

My Windows is XP SP3

« SpeedGuide.net TCP Analyzer Results »
Tested on: 04.19.2011 16:08
IP address: 200.101.xxx.xxx
Client OS: Windows XP

TCP options string: 020405ac0103030201010402
MSS: 1452
MTU: 1492
TCP Window: 261360 (multiple of MSS)
RWIN Scaling: 2 bits (2^2=4)
Unscaled RWIN : 65340
Recommended RWINs: 63888, 127776, 255552, 511104, 1022208
BDP limit (200ms): 10454kbps (1307KBytes/s)
BDP limit (500ms): 4182kbps (523KBytes/s)
MTU Discovery: ON
TTL: 48
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)

I'm from Brazil, and even here the download is limited to 2Mbps

Help please.

Thanks.

Sava700 · Post by **Sava700** » Tue Apr 19, 2011 4:45 pm

Run and set the Optimizer to Optimal settings to tweak your TCP... are you running anything in the background that is using up bandwidth when you test? Are you testing from here? http://www.speedtest.net

kdesc · Post by **kdesc** » Tue Apr 19, 2011 5:12 pm

Sava700 wrote:Run and set the Optimizer to Optimal settings to tweak your TCP... are you running anything in the background that is using up bandwidth when you test? Are you testing from here? http://www.speedtest.net

I configured with Optimal and restarted and nothing have changed and there is nothing else using bandwidth.

I did tests on lots of sites including http://www.speedtest.net that tests with servers near me, all these tests shows that my connection is 2Mbps.

I did various downloads from sites in my country and outside and the maximum bandwidth that I get is 207Kilobytes/s (2Mbps) instead of 750Kilobytes/s (7.5Mbps) that is what my modem supports like I have posted.

Any Idea?

I think that maybe my ISP forgot to configure my port to 10Mpbs...

Sava700 · Post by **Sava700** » Tue Apr 19, 2011 7:45 pm

kdesc wrote: I think that maybe my ISP forgot to configure my port to 10Mpbs...

It's possible you weren't provisioned correctly.. post the results from this test site to the forums please

http://miranda.ctd.anl.gov:7123/

kdesc · Post by **kdesc** » Tue Apr 19, 2011 8:15 pm

Sava700 wrote:It's possible you weren't provisioned correctly.. post the results from this test site to the forums please

http://miranda.ctd.anl.gov:7123/

I have used this site (http://ndt.switch.ch/) because the other is inaccessible to me.

WEB100 Enabled Statistics:
Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
checking for firewalls . . . . . . . . . . . . . . . . . . . Done
running 10s outbound test (client-to-server [C2S]) . . . . . 321.0kb/s
running 10s inbound test (server-to-client [S2C]) . . . . . . 1.35Mb/s

------ Client System Details ------
OS data: Name = Windows XP, Architecture = x86, Version = 5.1
Java data: Vendor = Sun Microsystems Inc., Version = 1.6.0_22

------ Web100 Detailed Analysis ------
Interprocess communications failed, unknown link type.
Link set to Full Duplex mode
Information: throughput is limited by other network traffic.
Good network cable(s) found
Normal duplex operation found.

Web100 reports the Round trip time = 561.56 msec; the Packet size = 1452 Bytes; and
There were 72 packets retransmitted, 379 duplicate acks received, and 427 SACK blocks received
The connection was idle 0 seconds (0%) of the time
S2C throughput test: Packet queuing detected: 39.74%
This connection is receiver limited 23.96% of the time.
This connection is sender limited 24.57% of the time.
This connection is network limited 51.47% of the time.

Web100 reports TCP negotiated the optional Performance Settings to:
RFC 2018 Selective Acknowledgment: ON
RFC 896 Nagle Algorithm: ON
RFC 3168 Explicit Congestion Notification: OFF
RFC 1323 Time Stamping: OFF
RFC 1323 Window Scaling: ON; Scaling Factors - Server=2, Client=8

Server 'ndt.switch.ch' is not behind a firewall. [Connection to the ephemeral port was successful]
Client is probably behind a firewall. [Connection to the ephemeral port failed]
Information: Network Middlebox is modifying MSS variable
Server IP addresses are preserved End-to-End
Client IP addresses are preserved End-to-End

trogers · Post by **trogers** » Thu Apr 21, 2011 8:49 am

Cost of a new ADSL2+ gateway (router cum modem) to handle 10mbps is only about USD80. Why remain happy paying for 10 mbps and get only 7.4 mbps?

kdesc · Post by **kdesc** » Thu Apr 21, 2011 11:04 am

trogers wrote:Cost of a new ADSL2+ gateway (router cum modem) to handle 10mbps is only about USD80. Why remain happy paying for 10 mbps and get only 7.4 mbps?

Yes, I have bought yesterday a new D-Link modem that supports ADSL2+, but looks like my Provider don't support ADSL2+.

My modem shows this:

Mode: G.DMT
Type: Fast

____________________Downstream__Upstream
SNR Margin (dB):______5.8_________21.0
Attenuation (dB):______16.0________11.0
Output Power (dBm):___11.8________12.5
Attainable Rate (Kbps):_6368________960
Rate (Kbps):__________6336________416

Instead of having an ADSL2+ "Mode" I have a G.DMT that supports only 8Mb and even so I can only download up to 2Mb speed.

I already have called the support and I'm still waiting they to fix this problem.

My doubt is that if I have bought 10Mb and my modem shows 6Mb at least I would be able to download at 700Kbps instead of my actual 205Kbps (of course at 10Mb I would be downloading at more or less 1100Kbps).

Is this a simple thing to fix or is more complex?

Thanks

trogers · Post by **trogers** » Fri Apr 22, 2011 10:41 am

kdesc wrote:Yes, I have bought yesterday a new D-Link modem that supports ADSL2+, but looks like my Provider don't support ADSL2+.

My modem shows this:

Mode: G.DMT
Type: Fast

____________________Downstream__Upstream
SNR Margin (dB):______5.8_________21.0
Attenuation (dB):______16.0________11.0
Output Power (dBm):___11.8________12.5
Attainable Rate (Kbps):_6368________960
Rate (Kbps):__________6336________416

Instead of having an ADSL2+ "Mode" I have a G.DMT that supports only 8Mb and even so I can only download up to 2Mb speed.

I already have called the support and I'm still waiting they to fix this problem.

My doubt is that if I have bought 10Mb and my modem shows 6Mb at least I would be able to download at 700Kbps instead of my actual 205Kbps (of course at 10Mb I would be downloading at more or less 1100Kbps).

Is this a simple thing to fix or is more complex?

Thanks

ADSL2+ is backward compatible to ADSL2, which should be the least your ISP is running in order to sell 10 mbps plans. The old ADSL can only support up to 8 mbps.

http://forums.speedguide.net/album.php? ... mentid=447

My guess the issue lies in the quality of the phone line.

kdesc · Post by **kdesc** » Fri Apr 22, 2011 11:25 am

trogers wrote:ADSL2+ is backward compatible to ADSL2, which should be the least your ISP is running in order to sell 10 mbps plans. The old ADSL can only support up to 8 mbps.

http://forums.speedguide.net/album.php? ... mentid=447

My guess the issue lies in the quality of the phone line.

The quality of the phone line is a interesting subject.
I have connected my modem in other point in my house and now I get this:

Comparison between old place and new place:

____________________Old Down_____Old Up__|__New Down____New Up
SNR Margin (dB):______6.4__________21.0____|__12.1_________16.0
Attenuation (dB):______16.0_________11.0____|__18.0_________13.0
Output Power (dBm):___11.8_________12.5____|__13.8_________12.5
Attainable Rate (Kbps):_6208_________960____|___4800________800
Rate (Kbps):__________6176_________416____|__4768________416

But I still get the SAME DOWNLOAD SPEED!!!

Looks like my connection is limited to 2Mbps somewhere because the variation from attenuation from 16 to 18 and SNR Margin from 6.4 to 12.1 didn't changed anything.

I only get at maximum 205kbytes/s that is equivalent to a connection of approximately 1900kbits/s.

trogers · Post by **trogers** » Fri Apr 22, 2011 7:29 pm

kdesc wrote:The quality of the phone line is a interesting subject.
I have connected my modem in other point in my house and now I get this:

Comparison between old place and new place:

____________________Old Down_____Old Up__|__New Down____New Up
SNR Margin (dB):______6.4__________21.0____|__12.1_________16.0
Attenuation (dB):______16.0_________11.0____|__18.0_________13.0
Output Power (dBm):___11.8_________12.5____|__13.8_________12.5
Attainable Rate (Kbps):_6208_________960____|___4800________800
Rate (Kbps):__________6176_________416____|__4768________416

But I still get the SAME DOWNLOAD SPEED!!!

Looks like my connection is limited to 2Mbps somewhere because the variation from attenuation from 16 to 18 and SNR Margin from 6.4 to 12.1 didn't changed anything.

I only get at maximum 205kbytes/s that is equivalent to a connection of approximately 1900kbits/s.

When you have multiple telephone wall sockets in the house, you have to make sure all phone devices connecting to the sockets are connected through a micro filter. If not, they will affect the internet signals.

http://www.broadbandwatchdog.co.uk/micro-filters.php

kdesc · Post by **kdesc** » Sat Apr 23, 2011 8:35 am

Today they changed my connection to ADSL2+ and now I have 10Mb and is working fine.
I'm getting 1.180Kbyte/s download speed.

Thank all of you that have replayed this thread.

Arzona Miller · Post by **Arzona Miller** » Sat Apr 23, 2011 8:49 pm

funny kdesc, im having same issue. i upgraded 2 wks ago to 10mbps, getting downloads of about 1.20mbps. ive tweaked and checked everything. i cant figure it out? someone help please!!! ive had 3 technicians from cl here, the one today plugged in his laptop to the 660 series modem on adsl and got 8mbps download speed and i get 1.20 or less daily . please help , this is driving me nuts!!!

http://www.speedtest.net/result/1266022382.png

kdesc · Post by **kdesc** » Mon Apr 25, 2011 8:20 am

Arzona Miller wrote:funny kdesc, im having same issue. i upgraded 2 wks ago to 10mbps, getting downloads of about 1.20mbps. ive tweaked and checked everything. i cant figure it out? someone help please!!! ive had 3 technicians from cl here, the one today plugged in his laptop to the 660 series modem on adsl and got 8mbps download speed and i get 1.20 or less daily . please help , this is driving me nuts!!!

http://www.speedtest.net/result/1266022382.png

This is what I'm getting at 10Mb

Post your modem configuration where it shows the ADSL rate and Mode like I did.

My problem was solved directly by them without any interaction here in my home, they changed the ADSL mode from G.DMT to ADSL2+.

Arzona Miller · Post by **Arzona Miller** » Tue Apr 26, 2011 8:08 pm

kdesc wrote:This is what I'm getting at 10Mb

Post your modem configuration where it shows the ADSL rate and Mode like I did.

My problem was solved directly by them without any interaction here in my home, they changed the ADSL mode from G.DMT to ADSL2+.

i looked at the modem config, it is set for adsl2+ but i will post the config..thx!