Billion 7700N

I've just taken delivery of a 7700N and I think there is something a bit strange going on. Before I start "fiddling" can anyone confirm that this is not right.

I have an ADSL2+ line. In the routers config (Advanced Setup / DSL) I have check marks against the following (the default settings)...

G.Dmt Enabled
ADSL2 Enabled
ADSL2+ Enabled
AnnexM Enabled

I assumed that these will be tried in reverse order, if it can't connect using ADSL2+ AnnexM it will try ADSL2+, and so on.

However, looking at the connection status (Device Info / Statistics / xDSL) I see that the mode is shown as ADSL_G.dmt; the manual indicates that I should see ADSL2+ (or maybe ADSL2plus) there. Some other stats, specifically line speed and attenuation, also seem to indicate that I am in normal ADSL mode.

I note that the manual also states "The router may require firmware modifications for certain ADSL2 / 2+ / Annex M DSLAMs". Anyone know anything about that?

The first step will be to disable G.Dmt and ADSL2, to see if that forces an ADSL2+ connection, but before I try, and risk the wrath of BT's DLM, I thought it worth asking here.

Ian

The router should connect in ADSL2+ mode with the default settings, if it doesn't try these settings which i have on my Billion 7800N (interface should be similar):
http://tinypic.com/r/16kak1u/7

Can i ask where you got the router from?

Thanks, I'll try those settings first. The layout is different, but the same fields are present.

I got it from BroadbandBuyer; £46.76 inc VAT

Ian

Those changes (Annex L on, G.Dmt off) made the difference. It now shows ADSL2plus and the downstream attenuation has increased by 4dB as expected.

Thanks

Can I ask how well it connects compared to your other ADSL modems? Sync speed wise / stability?

Thanks!

-- gyre --

It's a bit difficult to tell really. My main reason for changing router, I previously had a BT2700HGV, was to get one which could adjust the default SNR; because of a faulty low-energy light bulb BT's DLM had set mine to 9dB (from a very stable 3dB) and showed no inclination to drop it down again.

I've only had the 7700N for a couple of days and it seems stable. I've tweaked the SNR setting to default to 3dB, it drops to between 1 and 2dB at night, and I haven't seen any _unexpected_ re-syncs. The DLM is still generating a resync every 2 days though <sigh>.

Speed wise it seems slower than the 2700HGV. At 3dB that would give me 8500-9500 ish. The best I've seen so far from the 7700N is 7500 ish. I'm going to reduce the SNR adjustment again tomorrow so that might bring the speed up a bit more?

Other than that it seems quite a nice router. The wireless connection, using 2g, seems faster than the 2700HGV and it's nice to have a Telnet interface again.

Ian

Thanks for the info. I also have something similar... a 2700HG (no V). I'm on 9dB target snr. It's very stable, but I also miss the ability to tweak

I've ordered a 7700N myself today... will see how I get on. Hopefully it will run in just dumb modem mode connected to my draytek 2920.

-- gyre --

Received mine today from Broadbandbuyer.

Am using it in bridged mode on a very long line. So far I'm impressed with how well it is holding on.

Was oddly easy to set it into bridged mode. I was expecting it to be a real chore, as the advanced settings aren't for the faint of heart

-- gyre --

In reply to a post by gyre:

Received mine today from Broadbandbuyer.

Am using it in bridged mode on a very long line. So far I'm impressed with how well it is holding on.

Was oddly easy to set it into bridged mode. I was expecting it to be a real chore, as the advanced settings aren't for the faint of heart

-- gyre --

Interesting - thanks.Wondering if it would improve my sync rate.

How long is your line BTW -mine is 6.2km with an attenuation of 63 - around 82 @ 300KHz.

Barrie

I don't exactly know how long my line is. Before BT added extra checks to the 17070 number, they claimed it was about 4.7km. But lots of things have changed in the last few years, as I've been lifted and shifted at least twice.

My attenuation is shown at 63.5 using g.dmt. But then, I believe that it isn't specified to show anything larger. I force the system to use g.dmt as opposed to adsl 2+, as it gives a higher sync and appears more stable for me.

-- gyre --

Just received my Billion 7700n router how do i change the SNR ?.


Thanks in advance

Ashley

If it's anything like the 7800N you go to http://<router ip>/snr.html.

Explanation of the values here.

Edited by deleted (Mon 20-Jun-11 16:46:39)

The http link doesn't seem to work on a 7700N, it just gives a blank page?

I used Telnet to adjust the snr on my 7700N. Use the "adsl" command, as explained on the following page.

http://forum.kitz.co.uk/index.php?topic=5195.msg118218

Basically (assuming Windows) ...

Open a DOS shell in Windows
telnet 192.168.1.254 <enter> (on Windows 7 it will need to be enabled first, ask again)
admin <enter>
password <enter> (your normal router password, "admin" again by default)
adsl configure --snr 50 <enter> (for example, see above page)

The router should then re-sync with a lower snr.

Ian

That's too bad. I could never log in via telnet on the 7800. I think my password is probably too funky.

edit: scratch that. Just had a brainwave and PuTTY works fine, unlike Window's built-in client.

Edited by deleted (Mon 20-Jun-11 17:35:31)

Guys, can someone help me out with a easy walk through (tell me how), on how to telnet into my new 7700N, to lower the snr .

Cheers for any help

Sorted , i did not have telnet enabled in windows

Edited by toe (Wed 22-Jun-11 15:53:05)

Following up to my own post.

Using the modem in g.dmt mode, I'd get about 5 drops a day. No obvious reason.

Since using the modem in adsl2 mode, I've not had a drop. This thing holds on like grim death so far.

My downstream attenuation is shown as 66.5dB. My target snr margin is 9dB.

After tweaking the margin down to around 5.5dB, I sync at 2329kbps, which gives me a nice clean 2mbit/s profile.

I'm interleaved, so get quite a few FEC errors... around 85,000 in a 15 minute period at night. however, they are pretty much all corrected automatically, and the number of CRC errors is usually in single digits over 15 minutes.

I'm impressed with this router acting just as a modem so far.

In reply to a post by gyre:

Since using the modem in adsl2 mode, I've not had a drop. This thing holds on like grim death so far.

Sounds very similar to my thinking (so far).

I pushed mine a bit further; aiming for a target SNR of 3dB. After starting on that figure it slowly dropped over the next few days, and mainly nights, and now sits between ~0.2dB (nights) and ~1,0dB (days). The FEC figures at night are often over 1,000,000 in 5 minutes, and the CRC over 100 but the line has stayed up: just over 7 days so far at a sync of 7681.

I've come across a couple of oddities with the stats collection, but the hardware seems quite good.

Ian

In reply to a post by gyre:

I'm interleaved, so get quite a few FEC errors... around 85,000 in a 15 minute period at night. however, they are pretty much all corrected automatically, and the number of CRC errors is usually in single digits over 15 minutes.

I'm impressed with this router acting just as a modem so far.

You almost certainly get the same number of errors whether you're on interleaved or fastpath- the FEC count is those that were corrected, the CRC count is those that couldn't (more or less)

I use the 7800N on FTTC so can't speak about the modem bit, but Billion seem to have produced a good pair of routers.

I had the BT engineer out for another round of lift and shifts. This one seems to have done an excellent job... lowering my attenuation from 68dB to 62dB with a resulting sync increase from 2600kbps to 3600kbs.

Since then... over a week ago... the connection has stayed up rock solid. Well impressed with the 7700N to be honest.

-- gyre --

Are theses snr tweakable via telnet ?

"Are these tweakable by telnet?"

Yes
Start
type cmd
" telnet 192.168.1.254
login
password default is admin for both

type adsl configure --snr (between 1 and 199) 100 is default
type adsl profile --save

Thanks ;D