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WhyMe420
Premium Member
join:2009-04-06

WhyMe420 to ConstantineM

Premium Member

to ConstantineM

Re: AT&T U-verse FTTP speeds, why do they limit fibre to 18/1.5?

said by ConstantineM:

Come on, guys! Proper lines with proper wirings and lack of non-normal interference, which are merely distance-limited, would be totally fine to work at 100% capacity.

Nope. The VDSL needs FEC overhead in order to reliably keep sync at the profile used. When you use 100% of the line capacity, you almost always run out of reserve bits and usually end up over-committing the amount of bits required for the profile. Thus, line instability.
said by ConstantineM:

I'm not familiar with VDSL/VDSL2, but based on my prior ADSL research

Your post really shows that fact. I would recommend not stating "come on guys!" if you're not familiar with VDSL and wish to make claims against others. ADSL and VDSL are entirely different beasts. VDSL uses much higher frequencies which tend to attenuate a lot easier than ADSL. It's a pretty well-known fact around here by the regulars that 80% or less of the line capacity will be a lot more reliable than greater than 80%.

All the Max Rate is, is a number in which the VDSL modem was able to send a short burst of data through the line. It is by no means an actual indication of your line's capabilities. It is more of an estimate.
ConstantineM
join:2011-09-02
San Jose, CA

ConstantineM

Member

Funny you mention it, I was told the very same thing about ADSL and the 80% relative capacity occupation rule by all the regulars of the Sprint / Embarq forum (in fact, they even exercised much more firmness and certainty in the correctness of their rule than your prior post above), so I have no reason to believe that VDSL is any different, since all the sayings are the same, even the magic percentage points of the rule don't differ. (-:

The DSL equipment is obviously designed to withstand normal minor fluctuations of the line, so I'm still firm in my belief that there is no technical reason why lines would be unstable to the point of being unusable if they run at 100% capacity with no artificial limits imposed. ADSL can downgrade the sync speed if needed without loosing the connection at all (my ZyXEL did that flawlessly); I recall that ADSL2 or variants included provisions to reclaim the capacity back should line conditions improve (G.DMT can only go down or resync, but cannot go up without resync). I'm pretty sure VDSL should have similar provisions, being both moderate in the original sync speed, as well as being able to downgrade if the speed cannot be sustained, else VDSL would be fundamentally broken as a standalone protocol.
WhyMe420
Premium Member
join:2009-04-06

WhyMe420

Premium Member

Just because it doesn't lose sync doesn't mean it's not dropping packets. Sure, for TCP connections, it can simply retransmit the data, but for UDP, once a packet is dropped, that's it. When it comes to U-verse TV, dropped packets are not tolerable as they will cause picture/audio problems. Online gaming as well can't tolerate a lot of dropped packets. There's plenty of other things as well that can't tolerate dropped packets.

Regardless of what your equipment does, the U-verse VDSL equipment does not keep sync when the profile is dropped due to marginal line conditions. It will drop sync, then retrain to the lower profile, but, as I said already, at greater than 80% capacity there is no room for error correction, so basically the integrity of the line is not there, and there is no room at all for variances (thunderstorms, squirrels, temperature, rain, etc.)

So yeah while it might work (barely,) it's not what most people want. I can almost guarantee you that with over 80% line capacity being used, there will be uncorrectable blocks and sooner or later sync issues.
ConstantineM
join:2011-09-02
San Jose, CA

ConstantineM

Member

the 80% rule

I can only talk about my prior experience with G.DMT, and extrapolate to VDSL. However, back in the day I was explicitly told that my line would be unstable if they change my profile from 512 to 1.5 profile, by both the multiple official technicians that claimed it was impossible, as well as the regulars at dslreports, yet there I was afterwards, with my line syncing at 1.2Mbps and nearly zero CRC error count, with very minimal FEC error count, too (I was on interleave for the extra stability).

Packet loss is even more horrible with TCP than it is with UDP, and I recall having no packet loss for the many weeks I had been running at 96% downstream and 76% upstream, with effectively no artificial cap on the downstream speed whatsoever, with only the upstream being limited by the profile. So I'm here to say again that the 80% rule holds not much water: line is either really stable at 80% and pretty stable uncapped (e.g. near 100%), or it's hardly stable at 80% and quite unstable at 100%. There is no magic 80%. It's either a good line, or a bad line. I'd say even distance is irrelevant, based on my prior research as well as my old awesome 1.2Mbps far-away line that worked perfectly even after it was set free. Of course, there may be exceptions, but I'm convinced my case was not an exception instead.
WhyMe420
Premium Member
join:2009-04-06

WhyMe420

Premium Member

Sorry, but you're just talking outta your a**, first of all stating that TCP packet loss is worse than UDP, second of all saying "there is no magic 80%," when in fact 80% is the "magic" number as that is when you run out of reserve bits.
ConstantineM
join:2011-09-02
San Jose, CA

ConstantineM

Member

Of course TCP packet loss is worse than UDP, as the sliding window makes your throughput considerably slower than just mere retransmission. That's one reason TCP is not used for streaming video, as it would make it unacceptably slow very easily with just minimal, yet consistent, packet loss.

BTW, why are we even talking about TCP or UDP packet loss in the first place? Does VDSL, unlike ADSL, not support CRC and retransmission, as well as FEC? I think you're the one who doesn't know what they're talking about.

And what's so magic about 80% anyhow? Why do you need reserve bits in the first place; are you suggesting that unlike dialup and ADSL, and ADSL2, that VDSL/VDSL2 cannot simply downgrade the sync rate without loosing a connection? Because all these other mentioned technologies do that just fine!
WhyMe420
Premium Member
join:2009-04-06

1 edit

WhyMe420

Premium Member

said by ConstantineM:

Of course TCP packet loss is worse than UDP, as the sliding window makes your throughput considerably slower than just mere retransmission. That's one reason TCP is not used for streaming video, as it would make it unacceptably slow very easily with just minimal, yet consistent, packet loss.

Actually TCP is used in many forms of streaming video. It's not worse with TCP as, yes, throughput is slowed down, but at least it is retransmitted. When UDP packets are dropped, it is not retransmitted, thus, the data is lost for good. Not a hard concept to grasp.
said by ConstantineM:

Does VDSL, unlike ADSL, not support CRC and retransmission, as well as FEC? I think you're the one who doesn't know what they're talking about.

Your ignorance is shining here, as none of the xDSL technologies retransmit data. When the line is interleaved, FEC corrects errors in real time. If FEC is unable to correct the error, using the extra redundant data, then a CRC error is produced. CRC has nothing to do with retransmission. A CRC error means that the data is lost. That is why 80% is an important number, as the rest is needed for the redundant FEC overhead. Again, not a hard concept to grasp.
said by ConstantineM:

And what's so magic about 80% anyhow? Why do you need reserve bits in the first place; are you suggesting that unlike dialup and ADSL, and ADSL2, that VDSL/VDSL2 cannot simply downgrade the sync rate without loosing a connection? Because all these other mentioned technologies do that just fine!

None of these technologies do what you are saying, at all. If there are too many errors, the connection will lose sync and retrain. It's pretty amusing that you think that you are smarter than everyone on Earth, including technicians. Just like in the beginning of this thread, you were expecting to be the only person on Earth to have AT&T FTTP and 24/3 Internet.

EDIT: Here we go, just to seal the deal, a PDF relating to Broadcom PhyR, a new and little-used xDSL data retransmission system, that also explains how FEC, Reed Solomon, and Interleaving, do their job:
quote:
The RS + Interleaver scheme suffers from a high overhead burden because for every errored byte, two
additional overhead bytes must be transmitted to allow for a successful FEC correction. For example,
assuming that an overhead of 10% correctable is tolerable, correcting a burst of 1 ms of impulsive noise
(INP = 4 DMT symbols) requires an interleaver depth (or delay) of minimum 10 ms:

INP (ms) = ½ OH . delay (ms)

The ITU amendments mentioned above do not change anything in that fundamental limitation and only
intend to be as close as possible to the formula without introducing additional framing limitations.
Figure 1 clearly illustrates the capacity losses on an ADSL2+ system that complies with latest ITU
amendments for increasing INP when delay is constrained to 8 ms. When INP is set to 4 and at 16 Mbps
(4 kilobits per symbol), capacity loss is about 20%!
Source: »www.broadcom.com/collate ··· 01-R.pdf (page 3)

Notice that 20% number thrown in? What's 100% minus 20%? That's right, 80%. I rest my case.

As for the TCP/UDP thing, page 2 explains it just right:
quote:
ADSL has been a huge success for fast Internet access, but the job was rather easy from a service perspective;
rates are still fairly low (only a few Mbps) and Bit Error rate (BER) requirements are not too
stringent, as the TCP-IP retransmission protocol effectively hides transmission errors at these rates.
With the evolution towards IPTV, much lower BER figures are required. Typically, multicast video
streams are no longer protected by native retransmission protocols, no more than one error per movie is
allowed (equivalent with a BER lower than 10-10 for a 120’ movies at 20 Mbps), and application-level
retransmission protocols are expecting Ethernet-level BER to scale economically.
Therefore, it clearly explains that TCP makes it easier to accept line errors, whereas UDP and other protocols (such as used in certain video streams, online gaming, VoIP, etc.) require a lower BER, therefore they are not as tolerant to line errors.

Very simple concept.

Metatron2008
You're it
Premium Member
join:2008-09-02
united state

Metatron2008

Premium Member

Well he may be wrong on those issues, but coming in expecting to have the same speeds as people on copper is certainly a feasible argument to have.
WhyMe420
Premium Member
join:2009-04-06

WhyMe420

Premium Member

Well, it is pretty ridiculous how AT&T's FTTP is limited even more-so than their FTTN, but sometimes you just have to face the facts of life. The fact of the matter is that nobody on AT&T FTTP has accomplished what OP is wanting to do to this date. Hell, I would like to expect to have the same speeds as FiOS customers, but the fact of the matter is that Verizon doesn't serve my area, and even if they did they probably wouldn't deploy fiber around here.
dave006
join:1999-12-26
Boca Raton, FL

dave006

Member

Actually FTTP customers were provisoned above FTTN customers when the highest service profile was UvClass10 Stream Profile - 25Mbps profile (25/2). They were all at 30/3.6.

FTTP customer also still have a very big advantage in a very low latency connection, great for gaming! FTTP customers also don't have to worry about being put on a UvClass9 Stream Profile - 19Mbps profile (19/2) due to distance from the VRAD.

As has been previously indicated, until the hardware / software is upgraded on the FTTP plant, only the 30/3.6 profile is available.

Dave
WhyMe420
Premium Member
join:2009-04-06

WhyMe420

Premium Member

Agree with everything Dave . Though as it currently stands FTTP is (artificially) at a disadvantage in the bandwidth department, and 1.5Mbps upload is pretty bad for FTTP, IMO. Heck, I'd probably still choose it though, (that is, if I actually had a choice.)

DataRiker
Premium Member
join:2002-05-19
00000

DataRiker to WhyMe420

Premium Member

to WhyMe420
said by WhyMe420:

Well, it is pretty ridiculous how AT&T's FTTP is limited even more-so than their FTTN,

Ridiculous?

I would say more like semi-retarded and primitive. ATT's home run swing!

Metatron2008
You're it
Premium Member
join:2008-09-02
united state

Metatron2008

Premium Member

said by DataRiker:

semi-retarded and primitive

Now you know the secret to how the death star works

ConstantineM
join:2011-09-02
San Jose, CA

ConstantineM

Member

Alcatel HONT-C "155.52 Mbps upstream and 622.08 Mbps downst

I did a bit of research to find out the exact numbers as they relate to my equipment installed.

I found out that the ONT that I have is an Alcatel HONT-C, which supports "155.52 Mbps upstream and 622.08 Mbps downstream", according to Alcatel's specification. (This is an exclusive from ConstantineM, you won't hear it elsewhere! Noone seems to know what ONTs they have with U-verse!)

As it's a PON device, where a 16, 32 or 64 beam splitter must certainly be used for cost savings, this bandwidth is shared between all the 16/32/64 users, but, luckily, the notion of oversubscription of bandwidth is supported, according to wikipedia.

I presume AT&T is using either 32- or 64- beam splitters? In any case, these numbers clearly indicate a relationship of 4/1 of downstream/upstream bandwidth. I believe the total capacity in each direction is fixed regardless of distance (it either works or not), and I would equally imagine that there won't be any savings by leaving any of this bandwidth unused, since the downstream and upstream are entirely separate.

This brings into question why instead of going with something like 30/7.5 profile for FTTP, AT&T supposedly provisions FTTP with 30/3.6 instead, whereas FTTN VDSL gets 32/5.
Not sure if this is not news to other people, but IMHO this certainly brings it up to light the fact that there are really no hardware limitations whatsoever in offering 24/3 package to FTTP customers. In fact, I'd argue that the upload speed should really more closely represent the technology at hand, and the HSI offerings over FTTP should be something like 6/1.5, 12/3, 18/4.5 and 24/6, and not the outdated copper-style 6/1, 12/1.5, 18/1.5 and 24/3. In fact, since some speed must be reserved for AT&T's IPTV, which mostly (or even always) is to occupy the downstream portion of the connection, the upstream HSI spec offered might even be higher than that 4:1 ratio compared to downstream.

Not exactly sure about VDSL specifically (sorry, don't feel like researching technology I might never end up using!), but I think with copper as you get further away on the loop distance, any extra frequency you'd use in upstream, would have to dip into your downstream potential, so with VDSL, it indeed might make some sense to offer disproportionally lower upstream than downstream. However, with FTTP and fixed light capacity in both directions with a 4:1 ratio, it simply makes very little sense.

I want my 18/4.5! When you sell "18Mbps" (without upload speed being explicitly specified), and provide it via the above PON technology, it's only natural to assume that the upload speed would be exactly 4.5. Where's my 4.5? Why do I only get a third of that?

weaseled386
join:2008-04-13
Edgewater, FL

weaseled386

Member

Re: Alcatel HONT-C "155.52 Mbps upstream and 622.08 Mbps do

You need to look at it differently... you're barking up the wrong tree. You need to look at where FTTP and FTTN customers meet. Have you thought the limitation(s) may be the CO equipment instead? Stop looking at the medium its delivered on, and start looking at the equipment providing the stream.

houkouonchi
join:2002-07-22
Ontario, CA

houkouonchi

Member

said by weaseled386:

You need to look at it differently... you're barking up the wrong tree. You need to look at where FTTP and FTTN customers meet. Have you thought the limitation(s) may be the CO equipment instead? Stop looking at the medium its delivered on, and start looking at the equipment providing the stream.

I thought I remember hearing a AT&T employee say that VRAD's and stuff had like 10 gig uplinks or something?

The upstream still seems low but the 30 meg sync rate makes sense for bpon on uverse. With all the people using IPTV the network bandwidth would be a lot higher than say with FIOS where TV is handled on a different wave length and the full 622 megabits down is used for internet only (or 2.4 gigabits if on GPON like I am). Even if multicast is used I would think a big chunk of that 622 megabits would be used for TV traffic if split between 32 users.

weaseled386
join:2008-04-13
Edgewater, FL

weaseled386

Member

said by houkouonchi:

said by weaseled386:

You need to look at it differently... you're barking up the wrong tree. You need to look at where FTTP and FTTN customers meet. Have you thought the limitation(s) may be the CO equipment instead? Stop looking at the medium its delivered on, and start looking at the equipment providing the stream.

I thought I remember hearing a AT&T employee say that VRAD's and stuff had like 10 gig uplinks or something?

The upstream still seems low but the 30 meg sync rate makes sense for bpon on uverse. With all the people using IPTV the network bandwidth would be a lot higher than say with FIOS where TV is handled on a different wave length and the full 622 megabits down is used for internet only (or 2.4 gigabits if on GPON like I am). Even if multicast is used I would think a big chunk of that 622 megabits would be used for TV traffic if split between 32 users.

VRAD's for FTTN take 1G links, and its shared between 192 customers... with a possibility of 384 depending on the cabinets config. However, the Alcatel 7330 will not accept fiber and copper. A single VRAD is not the common point. You'd have to know if the FTTP people tie into the same Alcatel 7450/7500 equipment that the FTTN people do at the CO. For video we installed some sort of Fujitsu equipment, and they'd have to tie into it at some point... Dave006 would know much more about this than me, because I'm simply a hardware installing knuckle dragger
ConstantineM
join:2011-09-02
San Jose, CA

ConstantineM to weaseled386

Member

to weaseled386

Re: Alcatel HONT-C: 155.52 Mbps upstream / 622.08 Mbps downstrea

The CO can't possible have more strict limitation than the 622/155 PON G.983 FTTU hardware that is provided to the premises. Also, my complaint is now explicitly regarding upstream, and surely stuff at the CO has symmetrical bandwidth.

I looked more at the datasheet for HONT-C from Alcatel, and it seems like they suggest that 1:32 delivery must be used, e.g. all this 622/155 is shared by a mere maximum of 32 users.

155.52Mbps divided by 32 is clearly 4.86Mbps, as if the bandwidth could not be oversubscribed. In such light, the 3.6Mbps upstream part that, supposedly, everyone on FTTP is provisioned for, simply makes exactly zero (0) sense whatsoever. The alleged 30/3.6 FTTP profile should be more like 30/7.5 (if not higher in the first place), or, at the very least, 30/5 (with corresponding increase in HSI upload speeds), but not 30/3.6.

3.0Mbps is really the absolute minimum HSI upload speed that should be offered on the most expensive downstream package that's already been oversubscribed as far as FTTP profiles are concerned. This upload speed is a big value-add that comes entirely for free, yet rests absolutely unused and unaccounted for! This utter nonsense on AT&T's part is why stuff like internet hard drives still have virtually no place in our life today.

weaseled386
join:2008-04-13
Edgewater, FL

weaseled386

Member

All I see is wall of text, because you obviously are lost on this. Who cares what the ONT is listed for? It has NOTHING to do with the equipment thats installed in the field, and in the CO's.

The network card in my computer is 100M, and my switch is 1G. What does this have to do with anything? Nothing.
WhyMe420
Premium Member
join:2009-04-06

WhyMe420

Premium Member

said by weaseled386:

All I see is wall of text, because you obviously are lost on this. Who cares what the ONT is listed for? It has NOTHING to do with the equipment thats installed in the field, and in the CO's.

The network card in my computer is 100M, and my switch is 1G. What does this have to do with anything? Nothing.

It's a lost cause arguing with this guy. He's some guy that came in 15 days ago on a load of turnips that thinks he knows more than the entire DSLR community. Almost starting to think he's a troll.

weaseled386
join:2008-04-13
Edgewater, FL

weaseled386

Member

Successful Troll is successful
ohh
join:2011-07-16
San Jose, CA

ohh to WhyMe420

Member

to WhyMe420
said by WhyMe420:

said by weaseled386:

All I see is wall of text, because you obviously are lost on this. Who cares what the ONT is listed for? It has NOTHING to do with the equipment thats installed in the field, and in the CO's.

The network card in my computer is 100M, and my switch is 1G. What does this have to do with anything? Nothing.

It's a lost cause arguing with this guy. He's some guy that came in 15 days ago on a load of turnips that thinks he knows more than the entire DSLR community. Almost starting to think he's a troll.

I do not think he is a troll. Just because a group of people are easily pacified and willing to go with the flow does not mean they are correct. It just means they are easily pacified and willing to go with the flow. Those who are willing to easily bend over get it in many ways ;]

Those who have a cause are able to fight for what they believe in whether it be small or big. These forums give me the LULS because people are so malleable. Do you ever wonder why your government and big companies do not represent your interests? A majority of people cannot even stand up for their interests.. why would anyone else (i.e. to the looks of it people on this forum)?

At least he is researching and looking for answers. I respect that sort of will.
ConstantineM
join:2011-09-02
San Jose, CA

ConstantineM to weaseled386

Member

to weaseled386
Your switch supports 100M in addition to 1G, that's why your 100M card works. The ONT that I have only supports 622/155 PON, G.983, it does not support any other ON standards.

If you have some info about the equipment at the CO, or why exactly is this limitation sound or not, I'd be happy to hear it. But suggesting that the equipment at the CO is less powerful than the lowest standard equipment available to end users (which in fact matches specs for the network itself from third-party sources, too) just doesn't make any sense whatsoever.

Also, your response of "wall of text" to some explicit technical details I've contributed can only suggest that you're actually the one who's trolling here; in fact, I don't see you providing any contributions in this thread on the FTTP side of things.
WhyMe420
Premium Member
join:2009-04-06

WhyMe420 to ohh

Premium Member

to ohh
said by ohh:

said by WhyMe420:

said by weaseled386:

All I see is wall of text, because you obviously are lost on this. Who cares what the ONT is listed for? It has NOTHING to do with the equipment thats installed in the field, and in the CO's.

The network card in my computer is 100M, and my switch is 1G. What does this have to do with anything? Nothing.

It's a lost cause arguing with this guy. He's some guy that came in 15 days ago on a load of turnips that thinks he knows more than the entire DSLR community. Almost starting to think he's a troll.

I do not think he is a troll. Just because a group of people are easily pacified and willing to go with the flow does not mean they are correct. It just means they are easily pacified and willing to go with the flow. Those who are willing to easily bend over get it in many ways ;]

Those who have a cause are able to fight for what they believe in whether it be small or big. These forums give me the LULS because people are so malleable. Do you ever wonder why your government and big companies do not represent your interests? A majority of people cannot even stand up for their interests.. why would anyone else (i.e. to the looks of it people on this forum)?

At least he is researching and looking for answers. I respect that sort of will.

...Except for when the "cause" is wrong, and the masses are stating correct information. I am more inclined to believe all the U-verse technicians that post here, and the majority of people's experiences, than a single claim otherwise.

It's fine to look for answers, but to refuse to believe information stated by tons of people including technicians is just asinine. Why bother to look for answers, if you're only willing to listen to the answer that you believe is "correct?" If one were so smart on the matter, why would they be asking the question in the first place?
StLCardsFan
join:2011-06-06
Lafayette, LA

StLCardsFan to ConstantineM

Member

to ConstantineM

Re: AT&T U-verse FTTP speeds, why do they limit fibre to 18/1.5?

he is talking about upload speeds and their potential. ATT clearly doesn't want people uploading...and he seems to want to know why technically speaking ...why is ATT artificially limiting upload.

I wonder the same thing and no one ever really answers the question with anything other than ..why do you need that ..or blahblahblah is plenty.
etaadmin
join:2002-01-17
united state

etaadmin to ohh

Member

to ohh

Re: Alcatel HONT-C: 155.52 Mbps upstream / 622.08 Mbps downstrea

+1

Metatron2008
You're it
Premium Member
join:2008-09-02
united state

Metatron2008

Premium Member

If at&t didn't want uploading, then why does att's 3g have better upload usually then uverse?

The answer you are looking for isn't in what at&t wants you to do, the answer you are looking for is how much at&t is willing to spend to get you good speeds.
StLCardsFan
join:2011-06-06
Lafayette, LA

StLCardsFan

Member

said by Metatron2008:

If at&t didn't want uploading, then why does att's 3g have better upload usually then uverse?

The answer you are looking for isn't in what at&t wants you to do, the answer you are looking for is how much at&t is willing to spend to get you good speeds.

i dont think they have to spend anything to offer more speed for the fttp equipment.

as far as the phone data ...@$10/gb id sure as hell try to offer as much speed as possible.

weaseled386
join:2008-04-13
Edgewater, FL

weaseled386 to ConstantineM

Member

to ConstantineM
I know exactly whats inside of every Central Office in both Central & North Florida. As well as in nearly all RT's in the same areas. Why? Because I either installed it, supervised the installtion of it or quality checked the final product.

I'm sure you'd be happy to have a tour, see some pics, know the technical aspects of the backbone; you're simply not going to get it. Just like you'd like your 24/3 speeds, but you're simply not going to get those either.
gaforces (banned)
United We Stand, Divided We Fall
join:2002-04-07
Santa Cruz, CA

gaforces (banned) to StLCardsFan

Member

to StLCardsFan

Re: AT&T U-verse FTTP speeds, why do they limit fibre to 18/1.5?

said by StLCardsFan:

he is talking about upload speeds and their potential. ATT clearly doesn't want people uploading...and he seems to want to know why technically speaking ...why is ATT artificially limiting upload.

I wonder the same thing and no one ever really answers the question with anything other than ..why do you need that ..or blahblahblah is plenty.

Our government/law enforcement doesnt want us uploading at a fast rate so they can attempt to keep ahead of all the snooping they do. They are worried terrorists or a powerful influential group or individual would be able to gather enough forces to challenge thier authority.