1.60KM From Exchnage Only 4.8MB Connection Speed?

[Chrysalis]

I am guessing the 1.6km is straight line distance which means in reality your real line distance is probably much longer and probably is looking at your attenuation.

I am 1.65 from the exchange and I found out my real line distance is 2.96. Giving me an attenuation of 48-50. Like yourself I got fooled by the distance hype thinking it meant straight line distance so thought 1.65 was fine when I did the lookup before moving here.

[themelon]

If you have ever seen in some of the exchanges they sometimes have 1km worth of cable in a reel which doesnt help with the old distance chesnut! Generally if you have an old line you will get poorer results. A lot of older lines need replacing but BT wont do it unless it breaks. I had no joy trying to get them to replace my 1mb only line that cracled.......the quoted me £75

[Incomplete]

Line Attenuation (Up/Down) [dB]: 28.0 / 50.5

Your speed is normal and in spec for that attenuation. Your line is not exceptionally noisy I'm afraid it's just either a very attenuating line or a very indirect cable route.

[Chrysalis]

Originally Posted by themelon

If you have ever seen in some of the exchanges they sometimes have 1km worth of cable in a reel which doesnt help with the old distance chesnut! Generally if you have an old line you will get poorer results. A lot of older lines need replacing but BT wont do it unless it breaks. I had no joy trying to get them to replace my 1mb only line that cracled.......the quoted me £75

I have heard this as well, some lines been km before they exit the exchange which is a farce, surely its possible to shorten the line length inside the exchange or perhaps its a ploy to lower bandwidth demands on the BT network.

[Incomplete]

Originally Posted by Chrysalis

I have heard this as well, some lines been km before they exit the exchange which is a farce, surely its possible to shorten the line length inside the exchange or perhaps its a ploy to lower bandwidth demands on the BT network.

More that there's no requirement to shorten the line length and the engineers are stretched enough already without spending their time rewiring cables to reduce line lengths.

Nice conspiracy theory regarding the bandwidths but it's the same for everyone including LLU operators, some BT exchanges are really big and line length was not a consideration when they were built beyond supplying a functional voice service.

My line length is nearly triple my straight line distance by the way

[Gareth]

Anyone know how to determine the actual line distance, as opposed to as the crow flies? I seem to remember BT had an engineer's menu that you could call and one of the options was to measure the line distance.

---------- Post added at 20:29 ---------- Previous post was at 19:57 ----------

edit: Google is my friend

Distance From Exchange

Dial the same line test number as the quiet line test (17070). Then press option 3 (fast test) then press option 1 (to say you are authorised, don't worry about 'not being officially authorised'). The press option 2 (ring back test). Then put the phone down.

You will get called back by the test facility within about 10 seconds, one of the bits of information given will be distance from exchange (in kilometres).

*The distance result may not be accurate if you have a 'DACs' fitted. It is not 100% accurate but does serve as a guide.

source: http://www.the-scream.co.uk/forums/s...p?t=181&page=1

Wonder if this still works

[Incomplete]

On some exchanges it does but not many now, due to BT engineers being unable to access the service due to Joe Public congesting it trying to find out their line lengths

[Gareth]

[dragon]

Originally Posted by Incomplete

More that there's no requirement to shorten the line length and the engineers are stretched enough already without spending their time rewiring cables to reduce line lengths.

Nice conspiracy theory regarding the bandwidths but it's the same for everyone including LLU operators, some BT exchanges are really big and line length was not a consideration when they were built beyond supplying a functional voice service.

My line length is nearly triple my straight line distance by the way

When a lot of these exchanges were built the Internet didn't exist let alone broadband.

The DSLAM has to go where theres room for it, and if that means a long cable run then there not much that can be done.

[Incomplete]

LLU is especially vulnerable to this. The colo room to host OLO's DSLAMs isn't necessarily anywhere near the MDF so that run between MDF and HDF can add a fair distance with nothing BT or anyone else can really do about it.

[Chrysalis]

Originally Posted by Incomplete

More that there's no requirement to shorten the line length and the engineers are stretched enough already without spending their time rewiring cables to reduce line lengths.

Nice conspiracy theory regarding the bandwidths but it's the same for everyone including LLU operators, some BT exchanges are really big and line length was not a consideration when they were built beyond supplying a functional voice service.

My line length is nearly triple my straight line distance by the way

Note there 'wasnt' a requirement but now its important. So you havent explained why they cant do it. The only reason I can think of is saving money both in the labour requirement of doing the work and the bandwidth savings from people having lower synch speeds.

Its the same with the BRAS profiles, they drop within 75 minutes of a low synch but need 3 days to increase another way to save bandwidth,

---------- Post added at 00:05 ---------- Previous post was at 00:04 ----------

Originally Posted by Incomplete

LLU is especially vulnerable to this. The colo room to host OLO's DSLAMs isn't necessarily anywhere near the MDF so that run between MDF and HDF can add a fair distance with nothing BT or anyone else can really do about it.

BT cant do anything about their own building layouts?

[dragon]

Originally Posted by Chrysalis

Note there 'wasnt' a requirement but now its important. So you havent explained why they cant do it. The only reason I can think of is saving money both in the labour requirement of doing the work and the bandwidth savings from people having lower synch speeds.

Its the same with the BRAS profiles, they drop within 75 minutes of a low synch but need 3 days to increase another way to save bandwidth,

---------- Post added at 00:05 ---------- Previous post was at 00:04 ----------



BT cant do anything about their own building layouts?

To some extent no they can't becuase theres other Functioning kit in the rooms adjusent to the MDF, so they can't just rip it out to shove a DSLAM in there.

To rebuild half an exchange just to shorten the cable length to a Dslam by all of 100meteres ain't gonna happen

[Incomplete]

Originally Posted by Chrysalis

Note there 'wasnt' a requirement but now its important. So you havent explained why they cant do it. The only reason I can think of is saving money both in the labour requirement of doing the work and the bandwidth savings from people having lower synch speeds.

Bandwidth savings are irrelevant as the bandwidth BT supply is controlled by the MST and Ofcom anyway. If BT are found to be supplying a contention ratio that's too low they can be slapped.

Can I remind you that Openreach had to get permission to borrow workers from BT Wholesale in order to tackle the LLU installation backlog? This is not about BT being cheap. They are constantly hamstrung by the regulations they are forced to operate within.

There is an Openreach recruitment drive which has been running for a while I believe.

Its the same with the BRAS profiles, they drop within 75 minutes of a low synch but need 3 days to increase another way to save bandwidth,

Good reason for that and it's not related to saving bandwidth from BT's point of view but from making sure it's shared fairly. The traffic combing that's done wouldn't necessarily work properly if profiles bounced up and down along with sync in real time, it would require not inconsiderable BRAS resources.

I believe that BRAS profiles increase much more quickly now anyway? Speaking to a relative who has maxDSL his BRAS profile operates in near real time.

It's a pretty complicated system so putting it down to BT being cheap isn't really accurate. BT invested a not inconsiderable amount of cash in their maxDSL system, relative to that a few hundred Mbits of ATM bandwidth is nothing. Consider what BT are spending on 21CN as well. It's not about money.

BT cant do anything about their own building layouts?

Not really no. Exchanges weren't really built with hosting several racks of other operators' equipment in them. You think BT like having that extra copper there? They can't just rearrange MDF, UPS and all the other equipment in every exchange, it's not practical.

OLO hostels / colo rooms are placed where it is practical to place them. In some exchanges the space saved by removal of the analogue equipment is where that kit has to go. It's not just a random decision it has to be done based on availability of power, aircon, access and security arrangements, ease of jumpering, etc.

Again I don't see BT or any other telephone company in the world spending massive amounts of cash to rewire exchanges to shorten people's loops by a couple of hundred metres. After they do that then the question is asked why they can't rewire the outside plant to minimise cable lengths. It's really not worth under any circumstances, especially when FITL and FTTH aren't that far away and are a far more future-proof solution than wasting money on copper.

BT are spending billions on converting to an all-IP network, some sites are getting FTTH, FITL is under trial. The main thing holding these projects back is regulatory approval and regulatory regime.

Get Ofcom to allow BT to run fibre to homes with permission to put TV down it and without having to unbundle it and I think distance will quickly become irrelevant

[Chrysalis]

Originally Posted by dragon

To some extent no they can't becuase theres other Functioning kit in the rooms adjusent to the MDF, so they can't just rip it out to shove a DSLAM in there.

To rebuild half an exchange just to shorten the cable length to a Dslam by all of 100meteres ain't gonna happen

I think we talking diff levels of waste here. You are talking about rearranging an exchange to gain 100m.

I am talking about stopping having a km of cable of loop length wrapped around a spindle. This is confirmed in some exchanges I know off.

---------- Post added at 04:25 ---------- Previous post was at 04:14 ----------

Originally Posted by Incomplete

Bandwidth savings are irrelevant as the bandwidth BT supply is controlled by the MST and Ofcom anyway. If BT are found to be supplying a contention ratio that's too low they can be slapped.

Can I remind you that Openreach had to get permission to borrow workers from BT Wholesale in order to tackle the LLU installation backlog? This is not about BT being cheap. They are constantly hamstrung by the regulations they are forced to operate within.

There is an Openreach recruitment drive which has been running for a while I believe.



Good reason for that and it's not related to saving bandwidth from BT's point of view but from making sure it's shared fairly. The traffic combing that's done wouldn't necessarily work properly if profiles bounced up and down along with sync in real time, it would require not inconsiderable BRAS resources.

I believe that BRAS profiles increase much more quickly now anyway? Speaking to a relative who has maxDSL his BRAS profile operates in near real time.

It's a pretty complicated system so putting it down to BT being cheap isn't really accurate. BT invested a not inconsiderable amount of cash in their maxDSL system, relative to that a few hundred Mbits of ATM bandwidth is nothing. Consider what BT are spending on 21CN as well. It's not about money.



Not really no. Exchanges weren't really built with hosting several racks of other operators' equipment in them. You think BT like having that extra copper there? They can't just rearrange MDF, UPS and all the other equipment in every exchange, it's not practical.

OLO hostels / colo rooms are placed where it is practical to place them. In some exchanges the space saved by removal of the analogue equipment is where that kit has to go. It's not just a random decision it has to be done based on availability of power, aircon, access and security arrangements, ease of jumpering, etc.

Again I don't see BT or any other telephone company in the world spending massive amounts of cash to rewire exchanges to shorten people's loops by a couple of hundred metres. After they do that then the question is asked why they can't rewire the outside plant to minimise cable lengths. It's really not worth under any circumstances, especially when FITL and FTTH aren't that far away and are a far more future-proof solution than wasting money on copper.

BT are spending billions on converting to an all-IP network, some sites are getting FTTH, FITL is under trial. The main thing holding these projects back is regulatory approval and regulatory regime.

Get Ofcom to allow BT to run fibre to homes with permission to put TV down it and without having to unbundle it and I think distance will quickly become irrelevant

BRAS profile increases are as slow as ever and far from real time.

I did a calculation for thinkbroadband based on my last 2 months.

The result was just under half of my 60 days was spent waiting for BRAS profile increases, I am waiting for one now. The reason for this is my average synch length is currently 3-4 days, every 4 days I seem to drift down a BRAS profile and then the next synch higher up lasts for around 4 days but 3 of the days is on a lower BRAS profile. I even had a 0.25mbit BRAS for 2 days whilst on a 6494 kbit synch and even tho this was below my fault threshold BT wouldnt fix it and told me to simply wait for the next automated update.

I have question marks over how the BRAS rate limiting is handled as well. what is this 'traffic combing' that goes on?

I had 250kbit of bandwidth which is 5x the mount of dialup bandwidth and over 5x if you consider that dialup doesnt synch at the full 56kbit yet loading web pages etc. was slower then dialup considerably. I found out that when I loaded a web page packet loss exceeded 50% and retransmits went through the roof, it would seem that the BRAS rate limiting seems to forcefully drop packets. I have heard various excuses as to why they cannot make increases fast such as it would use too much resources which I then reply with why dont they increase these available resources and the response is cost. So money is a reason if you take that reply.

One guy gave me a reason why the BRAS profiles even exist and that is BT are trying to avoid a rare but bad fault condition that can occur if atm is allowed to hit its limit on throughput. Although again he couldnt give me a credible reason why BT are able to do a fast decrease but need 3 days to increase it. The amount of cpu power etc. thats needed to calculate if one qualifies for a blip logic would be better spent on just updating the BRAS profile after each synch event. If it means lots of upwards and downwards movements in BRAS profiles then perhaps BT should look into why people have such fluctuating conditions on their lines.

I assure you cost is a factor BT make many decisions every day to avoid cost.

[Incomplete]

Originally Posted by Chrysalis

I think we talking diff levels of waste here. You are talking about rearranging an exchange to gain 100m.

I am talking about stopping having a km of cable of loop length wrapped around a spindle. This is confirmed in some exchanges I know off.

I'd quite like to see where this is confirmed

I assure you cost is a factor BT make many decisions every day to avoid cost.

So do every other company, but trying to save bandwidth isn't a reason for them trying to save cash. A lot of BT's revenue streams are controlled externally and assume a certain level of costs, they can't raise and lower prices as they see fit for most products as you know and the labour required to shorten loop lengths in this manner wouldn't be trivial and would be a waste of time with FITL in the future.