Slight Loss Of Speed

quandam · Mar 16, 2009, 10:06:23

It's three days now since I got the 2700 up and running and have noticed a loss in speed. On my old Netgear I was getting beween 6.7mb and 7+ virtually all day long, I am now getting around 6mb ish with the 2700.

Could this be down to the numerous times I had disconnected the ADSL line over several days during my marathon set up fiasco and the line is monitoring and will eventually return to the higher speeds?

Any thoughts would be welcome

Rik · Mar 16, 2009, 10:15:31

It could be down to the disconnections. Go to:

http://192.168.1.254/xslt?PAGE=J03&THISPAGE=A02_POST&NEXTPAGE=J03

and let me know what figures you have for downstream attenuation, noise margin and sync speed would you.

Simon · Mar 16, 2009, 10:16:23

I believe it can take up to 5 days for things to level out, after a period of disruption, but someone more qualified will be along to confirm that.

quandam · Mar 16, 2009, 10:18:35

Quote from: Rik on Mar 16, 2009, 10:15:31
It could be down to the disconnections. Go to:

http://192.168.1.254/xslt?PAGE=J03&THISPAGE=A02_POST&NEXTPAGE=J03

and let me know what figures you have for downstream attenuation, noise margin and sync speed would you.

Rik

The link is not connecting. (404 error)

Rik · Mar 16, 2009, 10:20:48

Possibly a difference in firmware. Try:

http://192.168.1.254/xslt

then Broadband link > Details.

quandam · Mar 16, 2009, 10:34:47

Quote from: Rik on Mar 16, 2009, 10:20:48
Possibly a difference in firmware. Try:

http://192.168.1.254/xslt

then Broadband link > Details.

Rik

Downstream attenuation= 14.6

Noise Margin= 16db

Couldn't find sync speed, sorry!

Rik · Mar 16, 2009, 10:38:02

Run a BT speed test if you will, Q, that will give us the rest of the picture. With that attenuation, I'd expect you to sync at 8128, so I'm suspicious your profile may have dropped.

quandam · Mar 16, 2009, 10:45:54

Quote from: Rik on Mar 16, 2009, 10:38:02
Run a BT speed test if you will, Q, that will give us the rest of the picture. With that attenuation, I'd expect you to sync at 8128, so I'm suspicious your profile may have dropped.

Here it is Rik

Results Image not loaded

Test1 comprises of Best Effort Test: -provides background information.
Your DSL connection rate: 7616 kbps(DOWN-STREAM), 448 kbps(UP-STREAM)
IP profile for your line is - 6500 kbps
Actual IP throughput achieved during the test was - 6008 kbps

If you wish to discuss these results please contact your ISP.

If you are experiencing problems with specific applications, servers or websites please contact your ISP for assistance.

Your test has completed please close this window to exit the performance tester.

Rik · Mar 16, 2009, 10:48:25

That's a perfect test for your sync speed, Q. You've got interleaving turned on, which is dropping your max sync speed to 7616. It might be worth having a word with support and asking for it to be turned off.

quandam · Mar 16, 2009, 10:51:39

Quote from: Rik on Mar 16, 2009, 10:48:25
That's a perfect test for your sync speed, Q. You've got interleaving turned on, which is dropping your max sync speed to 7616. It might be worth having a word with support and asking for it to be turned off.

Thanks Rik. I will give them a call

quandam · Mar 16, 2009, 11:02:27

Quote from: Rik on Mar 16, 2009, 10:48:25
That's a perfect test for your sync speed, Q. You've got interleaving turned on, which is dropping your max sync speed to 7616. It might be worth having a word with support and asking for it to be turned off.

Rik

Rang CS, answered , wait for it, without a ring in about 10 seconds. Request sent to BT should be active from tomorrow. How does interleaving 'off' make a difference? (keep it simple

)

Thanks for the advice

Rik · Mar 16, 2009, 11:06:23

Interleaving is used when a line is thought to be error prone. Instead of sending data as a consecutive stream of packets, it re-arranges the packets so that they are sent 'out of order' and need to be re-assembled when they arrive. The idea is that one bad packet will require less re-transmission than if they were in normal sequential order. However, there is a processing 'cost' in interleaving which reduces the maximum sync speed. It also increases latency, by the order of 20ms according to accepted theory, though I have an interleaved line and can ping at 19-26ms, so I'm not totally convinced of that.

Steve · Mar 16, 2009, 12:24:40

Interleave appeared on my line during my brief foray (lack of UPnP) with the BT2700 HGV. It has now been removed and has not since been reintroduced.

I wonder how many users of the 2700HGV on the forum are interleaved?

Perhaps an unfair question in some ways as some are used on long lines when interleave may have a positive benefit. I am obviously more interested in responses from users with high downstream sync rates.

Rik · Mar 16, 2009, 12:35:08

I am.

quandam · Mar 16, 2009, 12:36:26

Quote from: stevethegas on Mar 16, 2009, 12:24:40
Interleave appeared on my line during my brief foray (lack of UPnP) with the BT2700 HGV. It has now been removed and has not since been reintroduced.

I wonder how many users of the 2700HGV on the forum are interleaved?

Perhaps an unfair question in some ways as some are used on long lines when interleave may have a positive benefit. I am obviously more interested in responses from users with high downstream sync rates.

Steve

I am approx 400 meters from the exchange with a steady connection so am hoping turning interleaving off will bring me back up to the higher speed

Steve · Mar 16, 2009, 12:43:06

In practical purposes I think the only thing you'll notice Q is the reduction in latency with interleave off. The difference in performance between a profile of 6500 and 7150 is at best marginal, only shown in speedtest results and not in overall download performance.

Rik · Mar 16, 2009, 12:44:18

You may be interested in a fuller explanation of interleaving, Q:

http://www.kitz.co.uk/adsl/interleaving.htm

quandam · Mar 16, 2009, 14:33:59

Quote from: Rik on Mar 16, 2009, 12:44:18
You may be interested in a fuller explanation of interleaving, Q:

http://www.kitz.co.uk/adsl/interleaving.htm

Thanks Rik

Den · Mar 16, 2009, 17:13:02

My profile for down load is 7616kbs with interleaving on, are we saying that if Idnet turn interleaving off I can go even faster. My 2700HGV has held the line for a couple of months now.

Lance · Mar 16, 2009, 17:17:39

Depending on your remaining noise margin, you might be able to go up to 8128!

Rik · Mar 16, 2009, 17:48:08

Which would give you a profile of 7150 rather than 6500, Den.

Steve · Mar 16, 2009, 18:28:45

Quote from: Den on Mar 16, 2009, 17:13:02
My profile for down load is 7616kbs with interleaving on, are we saying that if Idnet turn interleaving off I can go even faster. My 2700HGV has held the line for a couple of months now.

Another member with a potential full sync on the 2 wire with interleave on. Perhaps just coincidence.

quandam · Mar 17, 2009, 10:13:45

Quote from: stevethegas on Mar 16, 2009, 12:43:06
In practical purposes I think the only thing you'll notice Q is the reduction in latency with interleave off. The difference in performance between a profile of 6500 and 7150 is at best marginal, only shown in speedtest results and not in overall download performance.

Steve

It appears that BT have switched off interleaving and as you say I am still getting the slower speed reading (still good though!) as reported yesterday BUT everything is running much quicker and sharper and the ping reading has virtually halved. So, I think it is definitely a matter of leaving things well alone, as Shakespeare said

"If it ain't broke don't fix it!"
Thanks all for the advice.

Rik · Mar 17, 2009, 10:20:43

Shakespeare was a wise old bard.

Rik · Mar 17, 2009, 10:22:44

Afterthought, Q. You'll need to force a re-sync to go back to 8128...