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Technical News & Discussion => IDNet Help => Topic started by: jezuk1 on Apr 15, 2012, 12:24:10

Title: Thumbs up for LLU
Post by: jezuk1 on Apr 15, 2012, 12:24:10
Since switching over to the LLU service around 6 months ago it's been very reliable, I notice my connection resync'd last night (I guess there was some reset in the exchange) but I think this was my record for longest DSL sync time:

Apr 15 03:49:09 dsl-7800n.home.gateway   dsl-7800n pppd[549]: Connection terminated.
Apr 15 03:49:09 dsl-7800n.home.gateway   dsl-7800n pppd[549]: Connect time 93440.0 minutes.
Apr 15 03:49:09 dsl-7800n.home.gateway   dsl-7800n pppd[549]: Sent 15853202959 bytes, received 146940224638 bytes.


Very pleased, jolly good show idnet!
Title: Re: Thumbs up for LLU
Post by: Rik on Apr 15, 2012, 12:31:04
Glad to hear it's working well for you. :)
Title: Re: Thumbs up for LLU
Post by: Bill on Apr 15, 2012, 12:53:16
I've seen longer periods than that, but it's a medium length FTTC line so probably not a fair comparison.

IIRC, in the last year or so I've had two resyncs related to going from 40/10 to 80/20, another couple that I initiated because at the time I didn't realise that my lack of internet was a BT problem, and three when I knocked the power plug out of the modem :(

edit- ah, there was another when the DSLAM in the cabinet fell over!

I get the feeling that VDSL hangs on much better than ADSL, but it's no more than a guess.
Title: Re: Thumbs up for LLU
Post by: Lance on Apr 15, 2012, 14:01:51
Given there is less copper to soak up interference, I would expect that to be the case Bill.
Title: Re: Thumbs up for LLU
Post by: Bill on Apr 15, 2012, 15:41:23
Not sure its that simple... I've had quite a few occasions when it looked like a resync- brief red spike on the BQM, slight change of BT profile (in either direction), but nothing in the router log and my IPv6 address didn't change.

It's as though the DSLAM can do a partial resync "on the fly", perhaps re-arranging the higher frequency bins without having to re-assign the whole lot from scratch.

I don't even know if that's possible, but it would fit the (admittedly circumstantial) evidence :dunno:
Title: Re: Thumbs up for LLU
Post by: Steve on Apr 15, 2012, 15:49:43
Is seamless rate adaptation used on FTTC I wonder, there were rumours for adsl2+ but BT's not used it so far if I'm correct.
Title: Re: Thumbs up for LLU
Post by: Bill on Apr 15, 2012, 15:59:09
I hadn't heard anything about BT using SRA either, but then they're not the most open or communicative of organisations :P
Title: Re: Thumbs up for LLU
Post by: Glenn on Apr 15, 2012, 16:00:22
http://www.ispreview.co.uk/story/2011/09/22/bt-not-implementing-adsl2-broadband-seamless-rate-adaptation-technology.html
Title: Re: Thumbs up for LLU
Post by: Bill on Apr 15, 2012, 16:09:00
I should have said "I hadn't heard anything about BT using SRA with VDSL2..."
Title: Re: Thumbs up for LLU
Post by: Bill on Apr 15, 2012, 16:53:22
I raised it on tbb... RobertoS gave a very reasonable explanation:

http://forums.thinkbroadband.com/fibre/t/4113825-seamless-rate-adaptation.html
Title: Re: Thumbs up for LLU
Post by: esh on Apr 16, 2012, 12:14:50
LLU has been very reliable for me for a couple months too. The first few weeks there was the odd disconnect/reconnect but that seems to have sorted itself out.

The only downside to LLU is the minimum ping time has doubled (BT: 8ms, LLU: 20ms). But the benefits outweigh that fairly substantially right now.
Title: Re: Thumbs up for LLU
Post by: SSK on Apr 16, 2012, 12:33:33
Quote from: esh on Apr 16, 2012, 12:14:50
LLU has been very reliable for me for a couple months too. The first few weeks there was the odd disconnect/reconnect but that seems to have sorted itself out.

The only downside to LLU is the minimum ping time has doubled (BT: 8ms, LLU: 20ms). But the benefits outweigh that fairly substantially right now.

Immediately after I was switched to LLU there was a horrific weekend when throughput dropped from around 15Mbps to around 100Kbps (sometimes even lower!) but since then, and now for a few months, speeds have been rock solid around 16Mbps, with long periods (several hundred hours) without disconections. There wasn't much change in ping time.

So, after recovering from the traumatic weekend, the switch to LLU has been a good thing for me.
Title: Re: Thumbs up for LLU
Post by: jezuk1 on Apr 16, 2012, 12:43:49
QuoteThe only downside to LLU is the minimum ping time has doubled (BT: 8ms, LLU: 20ms)

My first-hop ping time actually reduced when I switched to LLU but it's probably due to whichever interleaving profile has been applied to your line at a guess.
Title: Re: Thumbs up for LLU
Post by: esh on Apr 18, 2012, 15:00:51
Supposedly I'm on fast path, but I don't know if fast/interleaving is the same as DSL1. Any one have any knowledge on that?