The 10 day training period ...

Hi Guys,

I've just had our new BT 21CN Annex M ADSL line installed and activated (day 3 today). It is supplied via BT from a smaller ISP - Talk Internet (who provide the handoff / IP allocation / bandwidth).

Given this is the first ADSL connection I've ever had, I'm a bit wet behind the ears, but I'm eager to make sure I'm getting the best combination of performance AND stability that I can.

I've ordered a Zyxel P660R-D, but in the mean time, I'm using a BT 2700HGV (v4.25.19 SBC 'unlocked' firmware), which I believe is only Annex A capable.

The line is working well and hasn't lost sync at all, but the speed is a bit disappointing. I ran a lot of speed tests, with varied MTU values (in the absence of the ISP telling me the recommended value). 1400 appears to work best and provides an average speed of ~9 Mbps, but indicative values are 14Mbps (from ISP and SamKnows). So .... slightly clearer

Current average speed: 9Mbps
Indicative (expected) speed: 14Mbps
Modem: BT 2700HGV (v4.25.19)
Distance from exchange: 800m
Socket: BT Openworld (new master socket)

DSL Line (Wire Pair): Line 1 (inner pair)
Protocol: G.DMT2+ Annex A
Downstream Rate: 20653 kbps
Upstream Rate: 1036 kbps
Channel: Fast
Current Noise Margin: 5.3 dB (Downstream), 7.9 dB (Upstream)
Current Attenuation: 28.0 dB (Downstream), 14.7 dB (Upstream)
Current Output Power: 18.4 dBm (Downstream), 10.0 dBm (Upstream)
DSLAM Vendor Information: Country: {0xB5} Vendor: {IFTN} Specific: {0xBE71}
PVC Info: 0/38

My cause for concern, is that the sync speed is 20MB, but the actual speed is MUCH lower.

During this "training period", is there anything special I should be doing to prompt a speed increase? Is the sync speed even relevant?

Should I be resetting the modem manually to force a re-sync?
OR
Should I leave it well alone, and make sure it doesn't re-sync?

Sync speed is king. Second to that is what your IP profile is set to, visit www.speedtester.bt.com to see what that is

No need to force a reboot of the router, the 20Meg is very good, and things may improve, a lot hinges on what the IP Profile is set to

@Andrew

Thanks for the quick response. I'm not on the site with the ADSL connection at the minute, but I think I'll drop tonight by and run that test.

I'll post back in ~30 mins

I was waiting for other views before commenting, Andrew, and agree with you that the sync is good for the attenuation.

I would in fact say it is exceptionally so, implying that something isn't being reported correctly. The target noise margin looks to be the standard 6dB.

You may not be able to get a BT speedtest - they have a server failure at present and access to speedtests is difficult if not impossible.

Where are you setting the MTU?

You can set it on both PC and router - and if the router is lower than the PC you can get a slow down.

I have seen some 2700's that have 1400 as the default - ones not setup for the UK/BT market which, if you are tweaking on your PC would suggest you have hit the right/matching value.

Try setting the router to 1492 and then te PC to 1478 or 1492

@MHC

I've just been trying it, but to no avail! I'll be around for another 1hr, so hopefully it will be remidied by then. It just hangs at "Checking user details"

MTU is set on the router only. PC is still on defaults.

@RobertoS

That doesn't sound good! Based on the att. what would you expect in terms of speed?

Edited by deleted (Wed 30-Nov-11 18:46:01)

When i was using 21CN i used PPPoE 1500MTU

seemed to work a lot better than PPPoA.

Which OS?

If Win7 then you will be OK as it will work out what value. If XP and the PC is set to 1500 you will have some issues.

XP. I'll revert back to 1500 then.

They may be lucky and have very little cross talk in their area.

It being an Annex M service, it may be behaving a little oddly, and misreporting.

Edited by MrSaffron (Wed 30-Nov-11 19:16:47)

MTU tweaking is not really about raw speed, but more about some sites not working at all.

ADSL2+ estimates if the 28dB is correct are 14000Kbps to 16900Kbps for connection speed. So line is performing beyond expectations if the numbers are correct that you posted.

The throughput may be a factor of a router that does not support Annex M, i.e. the negotiation and data presented by the router on screen may be wrong.

I would recommend getting an ADSL2+ Annex M capable router running on the line, and see how things pan out.

Annex M sacrifies downstream speed to gain about double the upstream speed, and this may have confused a modem that does not understand Annex M. I have seen some ADSL2+ Annex A only devices not work on lines where Annex M is active.

My Annex M modem is in the post and should be with me tommorow.

I think I'm being penalised here, just changed the MTU and on re-sync ...

Downstream Rate: 18001 kbps
Upstream Rate: 1045 kbps
Channel: Interleaved

Speedtest result: 6.7Mb/0.7Mb

It was previosuly set to FAST, so I'm guessing DLM is doing something silly here? Looking at the modem stats, there has been 6 re-syncs in the past 24hrs (is this normal?)

Edited by deleted (Wed 30-Nov-11 20:16:19)

Based on the att. what would you expect in terms of speed?

18 meg or less. Are you aware that when you do hang an annex M router off of it you will lose more downstream sync rate to provide the increased upstream ?

In reply to a post by Zarjaz:

Based on the att. what would you expect in terms of speed?

18 meg or less. Are you aware that when you do hang an annex M router off of it you will lose more downstream sync rate to provide the increased upstream ?

Yes, well aware. I guess its worth waiting for my new modem, as anything with this one could just be producing erroneous results due to a lack of Annex M support.

Speed is down to 6Mb/0.6Mb - this is dire!

To think I'm moving from a 10MB/10MB leased line to Annex M ADSL No, its not out of choice, but a fix until EFM is installed at the new site (90 day lead time).

Edited by deleted (Wed 30-Nov-11 20:31:45)

Sync Speed is the Dictator! The 10-day training period can only affect that and as your speed is exceptional, it could only worsen it . The 10-day period has no influence on your actual throughput, which is abysmal for some reason.

21CN WBC seems to flip-flop between Interleaved and Fast Path and, for me at least, Interleaved is about 0.5 Meg faster @ 19.3 Meg and is less error/discon prone.

I 'd consider 6 re-syncs in 24hrs to be excessive.

The influencing of sync speed continues for years, not just the ten days too

Okay, day 4 ...

No re-syncs in the past 24 hours, still on the 2700HGV until the Zyxel arrives.

Running the speedtest, a much healthier ....

Download speedachieved during the test was - 14501 Kbps
For your connection, the acceptable range of speeds is 4000-21000 Kbps.
Your DSL Connection Rate :18000 Kbps(DOWN-STREAM), 1074 Kbps(UP-STREAM)
IP Profile for your line is - 15881 Kbps
Upload speed achieved during the test was - 892 Kbps
Additional Information:
Upstream Rate IP profile on your line is - 1074 Kbps

But that was after a bit of a prompt to the ISP to see what the story was, so this could have been something at their end.

Looks a lot more promising to say the least. Lets see what I get on Annex M in the next few days ...

Okay, day 5 ...

When I ran the test last, it was about 10-11pm, and gave good throughput. However, this line is for an office, so outside of 9am-6pm is irrelevant.

Running the speedtest during the day ...

Download speedachieved during the test was - 4729 Kbps
For your connection, the acceptable range of speeds is 4000-15881 Kbps.
IP Profile for your line is - 15881 Kbps
Upload speed achieved during the test was - 862 Kbps
Maximum achievable is 1048 Kbps

Again, I'm new to ADSL - but a 10Mbps dropoff during the daytime just seems out and out unacceptable for an ADSL2+ Annex M line?

Do other (not part of BT Wholesale) tests show similar issues?

It is possible the issue is a capacity one, and if the small provider has a large business base, their peak time may be during the day.

Tests on TB and Speedtest net show the same results. The Tap3 test also shows ...

"Your service was found to be performing poorly."

So the ISP is to blame, not the line then?

Nothing has indicated the line to be a problem if memory serves me right, i.e. the copper wire to the exchange.

Probably something in the fibre or WBC network, Tap3 is meant to avoid ISP. So might just be exchange congestion if a LOT of businesses in that area.

Well, its pretty much a business park that we're in, surrounded by office buildings.

I guess there is nothing that can be done then

Well, I wanted to follow up on this.

Its been about 10 days now and the line should well and truly be trained. After a bit of investigation, the slow speeds I was seeing was a result of odd behaviour with the 2700HGV.

My Zyxel P660R-D1 arrived, I hooked it up and connected my Buffalo WHR-HP-AG108 (DDWRT) and ....

It syncs at 19500/2300 (Annex M) and in reality gives 17MB/2MB pretty much all day long.

http://www.speedtest.net/result/1643487818.png

I must say, I'm impressed and fairly happy.

When the Zyxel is in Annex A, it syncs at 2200 - vs. the 2700HGV at 18500 - what a difference!

... Now all I need to figure out is how to access the Zyxel interface when it is set up in full bridge mode (PPPOE by WHR-HP-AG108)