Why I regret joining virgin media

[Chrysalis]

Well previously I assumed when there was jitter this was due to bandwidth saturation on the ubr port.

But cable modem technology means they need a timeslot allocated to them and this can vary in situations of multiple users requesting at once, so I guess would explain a situation where one can upload at full speed (available bandwidth on UBR port) but still see's jitter (not available timeslot)?

[Ignitionnet]

Originally Posted by Chrysalis

Well previously I assumed when there was jitter this was due to bandwidth saturation on the ubr port.

But cable modem technology means they need a timeslot allocated to them and this can vary in situations of multiple users requesting at once, so I guess would explain a situation where one can upload at full speed (available bandwidth on UBR port) but still see's jitter (not available timeslot)?

No - the timeslots provided are when the modems actually transmit data so no timeslot allocation no transmission. The only transmissions that are done outside of provided timeslots are when modems come online and when they request timeslots to transmit.

A CMTS periodically (every 1-10ms) transmits (downstream) an upstream MAP for each upstream that services that downstream. This MAP indicates how the mini-slots are allocated for that period until the next MAP.

There are 3 mini-slot types - contention slots, where modems request data slots, these are unallocated unless DOCSIS 1.1 or higher QoS is being used so are CSMA. The CMTS tells the modems when the contention slots are coming up and they fight amongst themselves for them. This is what I mentioned as being that other source of congestion however with a typical upstream MAP frequency being between 1 and 4ms it's not a huge source of jitter.

Next is data slots, these are allocated to individual modems, so the MAP for these is a schedule of which modem gets to transmit, and how many mini-slots they get to transmit for.

Last are maintenance slots, there are two types of these. One is initial maintenance which are CSMA, for modems that are just coming online so the CMTS can't allocate them slots, it's not heard from them before, and there are station maintenance slots which are reserved for modems to respond to. You may notice that the T4 disconnect message refers to not seeing a unicast maintenance opportunity and this is what it refers to, that modem doesn't get a station maintenance slot in its' MAP for 35 seconds so considers itself disconnected.

A MAP is broadcast on the downstream for every upstream, so on the overlay network even though you can only acquire 1 upstream on your node you will see either 4 or 8 MAPs with different channel IDs depending on how many nodes your bonded downstream group covers and how many upstream ports are active on the card.

Congestion on the cable network is when all the data slots, and therefore usable upstream bandwidth, is being consumed. The bandwidth will never be 100% consumed as there will never be a case where every single burst fits exactly into every mini-slot however if all the data slots are consumed there is no usable bandwidth for modems to use to transmit their data.

[speedfreak]

Its not that bad through the day but now its garbage gaming wise. Odd thing is I absolutely cannot get above 10Mb on speedtests now



CEO guy is going to be getting annoyed with me soon looks like Im going to be mithering him for another week, must be something else going on if I have trouble on 50 and 20 and different parts of the network


Cant remember if I replied to you earlier pabs and cant be bothered to scroll back to look, but thanks for the info re the 50Mb CM might still work, I'll try it later

---------- Post added at 20:36 ---------- Previous post was at 20:07 ----------

yep the 50 works (well not works works but connects ok lol )

[Chrysalis]

ok thanks for the extra explanation, I dont understand it fully but have a better idea of it then earlier.

[Andrewcrawford23]

Originally Posted by speedfreak

Its not that bad through the day but now its garbage gaming wise. Odd thing is I absolutely cannot get above 10Mb on speedtests now



CEO guy is going to be getting annoyed with me soon looks like Im going to be mithering him for another week, must be something else going on if I have trouble on 50 and 20 and different parts of the network


Cant remember if I replied to you earlier pabs and cant be bothered to scroll back to look, but thanks for the info re the 50Mb CM might still work, I'll try it later

---------- Post added at 20:36 ---------- Previous post was at 20:07 ----------

yep the 50 works (well not works works but connects ok lol )

not read teh full thread but have your ever tried to download 3-4 files over 1 gig from the gamefiles.virginmedia.com site? if not i rec0ommend trying and see what speed oyu achive it might be higher than the speedtest site but i will be honest goign on the fact yoru ubr has fec errors and porbally low snr your unlikely to get full 50mb but you might you never know if you are unsure post the transfer rates of each file and me or someone else cna convert the speed to Mbit for oyu

[Ignitionnet]

Originally Posted by Andrewcrawford23

not read teh full thread but have your ever tried to download 3-4 files over 1 gig from the gamefiles.virginmedia.com site? if not i rec0ommend trying and see what speed oyu achive it might be higher than the speedtest site but i will be honest goign on the fact yoru ubr has fec errors and porbally low snr your unlikely to get full 50mb but you might you never know if you are unsure post the transfer rates of each file and me or someone else cna convert the speed to Mbit for oyu

Just curious, how do you know the uBR has FECs?

[speedfreak]

Sorry, forgot to reply Andrew, I've been through all that and they can be up and down. As Igni said though, Im curious how you knew that, have you looked or were you just guessing going from the gist of the thread?

Just a small update, the number of correctables I get on the modem doesnt correspond with the amount at the UBR (no idea what that figure is) so tomorrow a tech is coming to swap my 50Mb modem out, if its still the same then after that they are going to do a repull, Im just glad the installers seem to be very good at turning back the turf to bury the cable. Heres the number since tuesday evening, soon they will hit whatever the limit is and then start counting up again. 2nd line and networks seem to be adamant that the codewords wont have any affect on my line.

Power Level
(dBmV) 2.29 2.23 2.49 2.65
RxMER
(dB) 36.39 36.17 36.39 36.84
Correctable
Codewords 986037290 1613465874 1616483603 1256476504
Uncorrectable
Codewords 294 901 258 260


On a side note, big thumbs up to the other CEO office guy that took my call the other night, very helpful Even knew who I was from this thread as soon as I mentioned codewords to him. I think its good that people from VM take the time to read these threads on here. Im extremely happy they have carried on with it though I'll be even happier if it gets resolved

[pabscars]

Well at least its a proactive step forward and one step nearer a resolution hopefully speedy.

Glad to see you haven't thrown in the towel, as tempting as that was.

On a seperate note
(youre gonna have to put your hand in ya pocket and get the new MW2 maps ya tight git )

[speedfreak]

no way am I paying 10.99!! Im waiting for someone to give me his account details so I can download for free but the swine aint replied yet, I did the same for a few people on WaW map packs

I actually feel guilty thinking of leaving, its like all their hard work would be a waste and I do like VM as a company, might even switch my mobile to them but not if it doesnt get fixed.

forgot to mention they are also looking at my SA V+ box randomly rebooting and I've just read digi fanatic say they are sensitive to snr issues. Maybe a repull will sort it who knows. One think I do know is that its JD n coke night and the lag suits me when drinking now get off that little boys console and get on the manly ps3

Could someone clarify with a yes or no, do constant correctables affect your line? A brief explanation as to your answer would be great if you have the time I know we've probably been over this but a brief explanation to summarise would be great. This has gone on since end of jan and its alot to wade through to get a clear answer

[Sephiroth]

Constant correctables only affect your line if they become uncorrectable due to degrading line conditions. Otherwise they are corrected in line without affecting speed.

They should hardly be occurring though, IMO because it means something's not right on your line.

[speedfreak]

Originally Posted by Sephiroth

Constant correctables only affect your line if they become uncorrectable due to degrading line conditions. Otherwise they are corrected in line without affecting speed.

They should hardly be occurring though, IMO because it means something's not right on your line.

Thanks Seph, I can confirm that since all the work they have done, my uncorrectables dont climb, I also no longer get T4's . Saying that though my CM isnt on for weeks at a time with all the messing about, in the beginning the uncorrectables didnt climb but after a while went to 42000 as I posted ages ago. When you say somethings not right can you offer any explanation as to potential causes ? My pingplots obviously show issues so I'm after some hard information to offer VM, as much as the guy at VM wants to help theres little he can do if networks say it isn't an issue, believe it or not as I've said before, I never complain and I dont want anymore discounts I feel like someone moaning over nothing for money, but I know its not right no matter what networks say. That and its costing me a bomb to ring them from my mobile all the time

Might be totally unrelated but I cant stream anything in HD

Thanks for the help, YET AGAIN lol Im now off to hang a large meercat picture on the bedroom wall , not sure what the gf will say

[Sephiroth]

IMO, the correctables arise from four potential sources:

1/
Faulty modem (unlikely but possible)

2/
Noise ingress particularly at/from the street cabvinet to your modem. This would occur only if there was an RF situation caused by CB radio finding a strand of wire sticking out, maind feedback from another house, water in the wall box or tap box.

3/
Something going on in the wider VM network perhaps of the nature in #2 above.

4/
I'm not sure about this one but if there is no FEC mechanism in the routers other than CMTS, then any bit werror occuring in transport will only be detedted at your CM. That error could come from data source.

[speedfreak]

Thanks Seph, heres what I dont understand.... before they go through the effort of a repull, cant they just connect up at my cab to see if the codewords occur before reaching my CM and travelling down my cable ? Or am I thinking about it too basically? Dont forget that the other 2 guys on my UBR that posted also had the climbing codewords so whilst I remain optimistic that does throw a spanner in the works, maybe thats number 3

Dont like number 2 or 3 that would never be found!

Seph, as you have an o2 line , if you want a netgear dg834gt with dgteam firmware on so you can tweak the snr yourself, let me know and I'll post it to you, no charge as a thank you for all these months of help I dont need it so have it if you want, I'll even throw in a belkin shielded adsl cable

[Sephiroth]

Originally Posted by speedfreak

Seph, as you have an o2 line , if you want a netgear dg834gt with dgteam firmware on so you can tweak the snr yourself, let me know and I'll post it to you, no charge as a thank you for all these months of help I dont need it so have it if you want, I'll even throw in a belkin shielded adsl cable

A curry would be enough (although I don't feel I deserve it because all my advice is speculation!). If you want to lend me the modem - I'll accept. Perhaps you can advise me.

How would I take advantage of that firmware so as to raise my sync speed from 1.5 to 3 meg (the theoretical maximum for my distance)? I know I'd need to interact with O2 support - but will that firmware make a difference? I'm not as well up on that side of the broadband fence.

---------- Post added at 13:59 ---------- Previous post was at 13:55 ----------

Originally Posted by speedfreak

Thanks Seph, heres what I dont understand.... before they go through the effort of a repull, cant they just connect up at my cab to see if the codewords occur before reaching my CM and travelling down my cable ? Or am I thinking about it too basically? Dont forget that the other 2 guys on my UBR that posted also had the climbing codewords so whilst I remain optimistic that does throw a spanner in the works, maybe thats number 3

Dont like number 2 or 3 that would never be found!

Looking at the photo of a street cab, I'd say they could do what you suggest.

Are the other 2 guys on different street cabs?

#2 and #3 could be found quite easily IMO. #2 would be kicked off by the result of the cabinet test. #3 can be read in the CMTS MIBs available to 2nd line support.

[speedfreak]

Well had the CM changed, still got the codewords so its looking like a repull, also had the V+ box changed due to random reboots, now got the samsung one. Felt sorry for the tech he was here ages. Yes the other guys are on different cabs, Im in chorley, they are in preston. I've mentioned testing at my cab but its not happened, I'll ask again before the hassle of a repull

Seph, I'll try and search for some better info for you but looking here http://forum.o2.co.uk/viewtopic.php?...er=asc&start=0 it will work with o2 though you might need to put the latest firmware on. I used it with TT and it vastly improved my speeds and sorted out my noisy line, snr was up and down on my old router but very steady using this firmware on this one. I had loads of graphs showing how much better it was but they have been lost after a format There was no contacting ISP, you just access the router and theres a slide bar where you can increase or decrease your target SNR. For example TT had me set on SNR6 but I tweaked it down to snr1 and it was great Though tweaking it down too low sometimes affects throughput, its finding the right balance depending on your line
It has other benefits but I never found the time to get in to it all

Thanks for the info, I'll pass it onto VM and see what they say, pm me you're address and I'll post it out to you in the week, rather post you that than post you a curry


edit: found some of my old stats, not bad considering I had noise interfering with the line or it would have been higher

ADSL Link Downstream Upstream
Connection Speed 16671 kbps 1019 kbps
Line Attenuation 27.5 db 14.5 db
Noise Margin 2.7 db 10.6 db

You've nothing to lose if it doesnt work out you can just swap back to your router, I cant think of any reason you'd have to contact o2. If you're projected at 3Mb does your main phone socket have a test socket behind the faceplate? If so it might be worth you trying that if you havent already. The only thing i am unsure of is I was on LLU, I dont know if that matters or not