VDSL and ADSL Back Haul

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BumperBender

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Topic # 170908 30-Mar-2015 17:31

Hi, i have heard recently that in basic terms VDSL uses a different back haul to ADSL and the way it was explained to me was "if a cabinet in a street has 20 ADSL users and 5 VDSL users that with each technology using it's own back haul , VDSL is obviously going to have less contention and therefore improved performance again over an existing ADSL connection"

Unfortunately after searching different terminology i have been unable to find any documentation that supports this or confirms this, if anybody has knowledge of the back haul between a cabinet and the exchange any comments would be appreciated

My own experience with VDSL users who have moved from ADSL is they seam to be quite happy with the speed where with ADSL we were getting a few more complaints and the speeds are only 27248/9888 kbps for VDSL compared to the 18/0.9 mbps from ADSL so not a huge increase in down speed but a big increase in up speed and if i recall correctly zero complaints on internet speed since changing to VDSL - which lends some support to the above analogy

thoughts please

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Reply # 1273560 30-Mar-2015 17:31

Hello... Our robot found some keywords in your post, so here is an automated reply with some important things to note regarding broadband speeds.

If you are posting regarding DSL speeds please check that

- you have reset your modem and router

- your PC (or other PCs in your LAN) is not downloading large files when you are testing

- you are not being throttled by your ISP due to going over the monthly cap

- your tests are always done on an ethernet connection to the router - do not use wireless for testing

- you read this topic and follow the instructions there.

Make sure you provide information for other users to help you. If you have not already done it, please EDIT your post and add this now:

- Your ISP and plan

- Type of connection (ADSL, ADSL2, VDSL)

- Your modem DSL stats (do not worry about posting Speedtest, we need sync rate, attenuation and noise margin)

- Your general location (or street)

- If you are rural or urban

- If you know your connection is to an exchange, cabinet or conklin

- If your connection is to a ULL or wholesale service

- If you have done an isolation test as per the link above

Most of the problems with speed are likely to be related to internal wiring issues. Read this discussion to find out more about this. Your ISP is not intentionally slowing you down today (unless you are on a managed plan). Also if this is the school holidays it's likely you will notice slower than usual speed due to more users online.

A master splitter is required for VDSL2 and in most cases will improve speeds on DSL connections. Regular disconnections can be a monitored alarm or a set top box trying to connect. If there's an alarm connected to your line even if you don't have an alarm contract it may still try to connect so it's worth checking.

I recommend you read these two blog posts:

- Is your premises phone wiring impacting your broadband performance? (very technical)

- Are you receiving a substandard ULL ADSL2+ connection from your ISP?

I am the Geekzone Robot and I am here to help. I am from the Internet. I do not interact. Do not expect other replies from me.

sbiddle

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Reply # 1273694 30-Mar-2015 19:47

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BumperBender: Hi, i have heard recently that in basic terms VDSL uses a different back haul to ADSL and the way it was explained to me was "if a cabinet in a street has 20 ADSL users and 5 VDSL users that with each technology using it's own back haul , VDSL is obviously going to have less contention and therefore improved performance again over an existing ADSL connection"

Unfortunately after searching different terminology i have been unable to find any documentation that supports this or confirms this, if anybody has knowledge of the back haul between a cabinet and the exchange any comments would be appreciated

You won't find anything online because it's completely and utterly incorrect. Whoever told you clearly has no understanding of how the network works.

All UBA connections (whether ADSL2+ or VDSL2) are backhauled from the cabinet by Chorus either to the nearest ISP handover whether they have their own backhaul, or if the ISP chooses they can buy tail services to transport that traffic elsewhere in the country. They all share the same backhaul from the cabinet.

mercutio

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Reply # 1273748 30-Mar-2015 20:30

vdsl has lower overhead for small packets (well more noticable on smaller packets) it's called PTM instead of ATM. i've noticed less jitter on it as well.

a lot of the time people underestimate how much burst upload can be an annoyance. like if you send an email that's got a 1mb attachment on adsl that'll make the connection near unusable for about 10 seconds vs still usable with vdsl.

part of this is to do with buffer-bloat issues in modems where they queue a lot of data ready-to-send and can be helped by screwing around with qos settings on the modem. but it doesn't necessarily work well as small packets can often have higher overhead than larger packets. (due to atm cell overhead)

a lot of people seem to hit the vdsl upload cap. it's really annoying that chorus are speed capping it artificially. they're still also running at 12db snr margin :(

also in nz in general (on adsl and cable) there are small queue sizes by default on download that tend to limit international download speeds. some isp's stick more intelligent queuing on afaik, but because the speed isn't constant for adsl it's harder to do. (ufb's got similar issuues, but at least it has static speeds). i suspect these queue sizes are slightly larger for vdsl than adsl. (the adsl ones were fine for adsl1).

BumperBender

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Reply # 1273812 30-Mar-2015 21:37

Thanks for that info -that's exactly the sort of info i need to stay on track
To be honest the company would love to go Fibre but it's not available for a few years at least and i'm just trying to point out that for their use here and now VDSL may be quite a good option until Fibre is available

richms

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Reply # 1273854 30-Mar-2015 23:05

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If VDSL is available then it should be what you get. To stay on ADSL is just silly unless you are at the limit of VDSL where the speeds can be a little lower on the downstream, but better upstream if you never send anything to the internet.

Richard rich.ms

sbiddle

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Reply # 1273886 31-Mar-2015 07:23

I don't know why anybody who's in a VDSL2 coverage area would stay on, or even connect up a new ADSL2+ connection.

Jase2985

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Reply # 1273888 31-Mar-2015 07:34

sbiddle: I don't know why anybody who's in a VDSL2 coverage area would stay on, or even connect up a new ADSL2+ connection.

cost, being elderly, and have no need for the extra speed,

there are a few reasons, but most of the people on here its a no brainer

sbiddle

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Reply # 1273906 31-Mar-2015 08:25

Jase2985:
sbiddle: I don't know why anybody who's in a VDSL2 coverage area would stay on, or even connect up a new ADSL2+ connection.

cost, being elderly, and have no need for the extra speed,

there are a few reasons, but most of the people on here its a no brainer

Speed is not a measure of the performance of a connection so should never really be a factor in determining a connection type. The added upstream speed however makes a massive difference, purely because of how TCP/IP works.

QoE is all that matters, and the simply reality is the move to PTM from ATM and having increased upload delivers a vastly superior perceived customer experience.

jnimmo

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Reply # 1273910 31-Mar-2015 08:39

What they/you may have been referring to is the average minimum throughput per connection (to the ISP backhaul); with UBA ADSL etc I think it is 32kbps as a minimum, with VDSL I believe it is 96kbps

sbiddle

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Reply # 1273939 31-Mar-2015 08:48

jnimmo: What they/you may have been referring to is the average minimum throughput per connection (to the ISP backhaul); with UBA ADSL etc I think it is 32kbps as a minimum, with VDSL I believe it is 96kbps

EUBA products have no artificial per user dimensioning in the real world. It's only users on UBA that have enforced handover dimensioning.

Athlonite

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Reply # 1273948 31-Mar-2015 09:06

the speeds are only 27248/9888 kbps for VDSL compared to the 18/0.9

I would have expected a much better VDSL2 sync than that considering you were getting 18Mbps on ADSL2+, 27.2Mbps on VDSL seems low I get that and I only had 14.9Mbps on ADSL2+

Jase2985

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Reply # 1274220 31-Mar-2015 12:18

sbiddle:
Jase2985:
sbiddle: I don't know why anybody who's in a VDSL2 coverage area would stay on, or even connect up a new ADSL2+ connection.

cost, being elderly, and have no need for the extra speed,

there are a few reasons, but most of the people on here its a no brainer

Speed is not a measure of the performance of a connection so should never really be a factor in determining a connection type. The added upstream speed however makes a massive difference, purely because of how TCP/IP works.

QoE is all that matters, and the simply reality is the move to PTM from ATM and having increased upload delivers a vastly superior perceived customer experience.

that may be entirely true but to some people it just does not matter, which is the fact you are overlooking

someone who goes online to check emails and the occasional Skype call once a week to family doesn't need VDSL. Also some cant afford or justify the extra cost.

you don't buy a Holden GTS because you use your car once a week to go down to the shops and for the occasional visit to family. you buy something that is practical and that you can afford.

For some people they want/need the extra speed, which is accompanied by an extra cost, others don't. its got nothing at all to do with how the technology is delivered or about QoE. hell they probably dont even know what they mean or how they work so they are completely irrelevant in their decision making process

webwat

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Reply # 1275635 1-Apr-2015 19:16

sbiddle:
Jase2985:
sbiddle: I don't know why anybody who's in a VDSL2 coverage area would stay on, or even connect up a new ADSL2+ connection.

cost, being elderly, and have no need for the extra speed,

there are a few reasons, but most of the people on here its a no brainer

Speed is not a measure of the performance of a connection so should never really be a factor in determining a connection type. The added upstream speed however makes a massive difference, purely because of how TCP/IP works.

QoE is all that matters, and the simply reality is the move to PTM from ATM and having increased upload delivers a vastly superior perceived customer experience.

I don't want to pay extra to get VDSL2, but I suspect wouldn't help too much since I have 40dB attenuation. The master splitter helps, and I switched modulation to Annex M to give me 6.8 megs down and 1.6 megs up. Speed is only a problem on weekends... probably congestion at Slingshot.

Qualified in business, certified in fibre, stuck in copper, have to keep going ^_^

webwat

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Reply # 1275638 1-Apr-2015 19:21

BTW QoE means Quality of Experience... its all about perceptions and that was the point. If the experience only requires dialup to FEEL fast then thats all they need. Unlikely, but the experience is all that matters.

If your ISP seems congested because you only ever use your superfast connection when the ISP has a broken network, its still a terrible experience.

Qualified in business, certified in fibre, stuck in copper, have to keep going ^_^

mercutio

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Reply # 1275662 1-Apr-2015 19:45

webwat:
sbiddle:
Jase2985:
sbiddle: I don't know why anybody who's in a VDSL2 coverage area would stay on, or even connect up a new ADSL2+ connection.

cost, being elderly, and have no need for the extra speed,

there are a few reasons, but most of the people on here its a no brainer

Speed is not a measure of the performance of a connection so should never really be a factor in determining a connection type. The added upstream speed however makes a massive difference, purely because of how TCP/IP works.

QoE is all that matters, and the simply reality is the move to PTM from ATM and having increased upload delivers a vastly superior perceived customer experience.

I don't want to pay extra to get VDSL2, but I suspect wouldn't help too much since I have 40dB attenuation. The master splitter helps, and I switched modulation to Annex M to give me 6.8 megs down and 1.6 megs up. Speed is only a problem on weekends... probably congestion at Slingshot.

must mean you're on their gear. it's unfortunate that chorus don't support annex m or lower snr margins, but it really helps on distant connections.

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