Benefit of DG834G v5 over v3

davej99 · Oct 26, 2010, 17:18:47

Hope this is of use to others on a line that is on the limit of a maximum connection (1.7m exchange distance by road).

Problem: After several years my interleaved ADSL connection has recently degraded from a max 8128 sync and 7150 profile to 7104 and 5500 respectively. The lower sync arose after a reboot following september vacation. The noise margin fell to 9db daytime, whereas on the max sync it ran at 12db. I never lost sync, but the line seemed to have got much noisier (spikey) in RouterStats.

Action: After all the usual checks I upgraded to the DG834Gv5 from and old virgin DG834GSPv3. The line immediately sync'ed at 7616 and the profile rose in a few hours to 6500. Down attenuation improved from 37 to 35.5db. The daytime noise margin is near flat lining at 9db with the occasional short dip to 8.5. I am optimistic I will see a better sync in due course.

Conclusion: Either v5 is better on a noisy line that v3, or my old v3 was on the way out. At worst it was worth £29 to get a standby router.

Downside: No bits/tone data in v5. No router log, DOS etc email report I can find.

Speculation: We have just been LLU'd, so I was wondering if I was re-routed by BT to accommodate handover in the exchange giving more noise. (It's TalkTalk LLU btw

)

Rik · Oct 26, 2010, 17:23:22

Thanks for that, Dave. Generally, the v4 is better thought of than the v5, but the v3 was certainly getting long in the tooth.

I doubt you've been re-routed, LLU work is done at the exchange. Possibly the extra equipment is generating some noise there, but that's a wild guess.

davej99 · Oct 26, 2010, 18:47:40

Quote from: Rik on Oct 26, 2010, 17:23:22
Possibly the extra equipment is generating some noise there, but that's a wild guess.

Maybe it's new LLU customers frying the wires to TTalk Tech Support. "Sorry, it's an 18 month contract!!"

.Griff. · Oct 26, 2010, 19:45:03

The V3 uses a Texas Instruments chipset where the V5 uses a Broadcom chipset. Maybe Talk Talk use Broadcom DSLAM's?!?!?

Steve · Oct 26, 2010, 19:56:03

I thought the V5 was a Conexant CX94610 chipset. Mind you I don't know who owns what anymore.

.Griff. · Oct 26, 2010, 20:10:32

Quote from: Steve on Oct 26, 2010, 19:56:03
I thought the V5 was a Conexant CX94610 chipset. Mind you I don't know who owns what anymore.

You're correct.. Long day..

Lance · Oct 26, 2010, 23:17:21

It looks like the sync is being limited by have interleaving on. I bet (as long as your line is stable and relatively error free) getting support to ask BT to turn it off would yield the full sync.

davej99 · Oct 27, 2010, 12:01:18

Quote from: Lance on Oct 26, 2010, 23:17:21
It looks like the sync is being limited by have interleaving on. I bet (as long as your line is stable and relatively error free) getting support to ask BT to turn it off would yield the full sync.

Thanks for that idea Lance. Do the following stats support such a request?

Noise Margin: 9.0 dB
Connection Rate: 7616 Kbps
Line Attenuation: 36.0 dB

Corrected Errors:
HEC : 0
FEC : 86
CRC : 0

Uncorrected Errors:
LOS : 0
SES : 0
ES : 0

3h32m minute sampling

Edited with correct sample time

Rik · Oct 27, 2010, 12:31:10

Over what period is that, Dave?

davej99 · Oct 27, 2010, 12:40:41

Quote from: Rik on Oct 27, 2010, 12:31:10
Over what period is that, Dave?

About 3h32. (Edited)
Never paid much attention to interleaving because I always had 8128 sync and 7150 profile with interleaving on. Maybe things have changed and I am now just getting the more usual 7617 interleaved maximum per Lances post.

Rik · Oct 27, 2010, 12:42:41

Can you report back in 24 hours, Dave, without re-booting the router, so that we can see what the error count reaches. My first thought it that you should be OK without interleaving.

MisterW · Oct 27, 2010, 12:44:43

The normal maximum sync with interleaving on is 7616, some routers, however, can support something called S 1/2 mode which allows them to sync up to the 8128 max, even with interleaving on. Its possible that interleaving has always been on and that the DG834 v3 could support this whereas the v5 can't and is limiting to 7616.

davej99 · Oct 27, 2010, 12:51:08

Quote from: Rik on Oct 27, 2010, 12:42:41
Can you report back in 24 hours, Dave, without re-booting the router, so that we can see what the error count reaches. My first thought it that you should be OK without interleaving.

Think I may be wrong on the FEC count. Plotting in RouterStats, which is the 15 min interval, it is running 3, or 12 per hour. The figure I have earlier is the time since boot, currently 86 in 3h32m.

Lance · Oct 27, 2010, 12:58:30

It certainly looks like it will be ok to me, but as Rik has said with 24 hours worth of data we can make a much better judgement.

davej99 · Oct 27, 2010, 13:19:55

Quote from: Lance on Oct 27, 2010, 12:58:30
It certainly looks like it will be OK to me, but as Rik has said with 24 hours worth of data we can make a much better judgement.

Just in case I am stuck with interleaving, I thought I would check if the DG834Gv5 supports s=1/2 and have had no luck finding an answer. Does anyone know? If it does not, I need to send it back right now. V3 definitely hit 8128 sync with interleaving on.

Rik · Oct 27, 2010, 16:42:34

I don't know, Dave, sorry.

davej99 · Oct 27, 2010, 16:54:22

Just descoverd v5 is End of Life and firmware is frozen. Were memory problem too. I think I will return it anyway. Anyway can't access bits and swaps per tone data, which is handy. Seems designed down to a price. Thx for your help, Rik

Rik · Oct 27, 2010, 16:56:22

All Netgears are designed down to a price, Dave, it's what the market demands.

Glenn · Oct 27, 2010, 16:57:45

What is s=1/2, Dave?

Steve · Oct 27, 2010, 17:18:45

I know half the answer

This is dependent upon your router being able to support S=1/2 mode which effectively combines two RS code words into a larger logical code word of 510 bytes (ANSI T1.413).

Read more: http://www.kitz.co.uk/adsl/interleaving.htm#ixzz13Zo6ZaBf

Glenn · Oct 27, 2010, 17:24:37

davej99 · Oct 27, 2010, 20:07:42

Quote from: Glenn on Oct 27, 2010, 16:57:45
What is s=1/2, Dave?

The answer is:

Quote from: MisterW on Oct 27, 2010, 12:44:43
The normal maximum sync with interleaving on is 7616, some routers, however, can support something called S 1/2 mode which allows them to sync up to the 8128 max, even with interleaving on. Its possible that interleaving has always been on and that the DG834 v3 could support this whereas the v5 can't and is limiting to 7616.

Thanks for that MrW. This was an eye opener, not least because I am on a line where I can get full sync with S=1/2 mode but not without. Which is why I am sending the DG834gv5 back from whence it came. That and because I learned on the Netgear forum that it is end of life and no more firmware is expected. In fact features were recently removed in the last upgrade because of memory problems.

Lesson: Listen to this forum before parting with the hard earned!

Rik · Oct 28, 2010, 08:24:02

We normally spend other people's money, Dave, we must be slipping.