1.5Mbit upload. Is it sufficient?

[Cheekykid]

There was much debate about the 1.5 upload speed. Many were saying that 1.5 isn't enough and it would limit the download. What is the case now that the product has been released?

[Stabhappy]

Many people are reporting the upload is actually 1.75 and the download is actually 52mb - to account for overheads. A smart move by virgin really.

[Aser]

52mb and they're advertising it as 50mb? That's different. usually they give a lower speed than they advertise. e.g. 20mb is actually 19.5mb in the config file.

[Ignitionnet]

52mb and they're advertising it as 50mb? That's different. usually they give a lower speed than they advertise. e.g. 20mb is actually 19.5mb in the config file.

VM have never put a config file lower than the advertised performance - that would be illegal.

The one instance of issues was where the M tier on ex-ntl platform had 200kbps rather than 256kbps upstream, never been the case with downstream. Telewest tended to cap 10% or so higher, and the original cable modem product from ntl was advertised at 512kbps but config file was 600kbps.

[Aser]

Well on my modem with the 20mb service, it states the the downstream speed is 20480000 bps.

20480000 / 1024 / 1024 = 19.53mb.

[Stabhappy]

That's mebibits, not megabit.

[Ignitionnet]

Well on my modem with the 20mb service, it states the the downstream speed is 20480000 bps.

20480000 / 1024 / 1024 = 19.53mb.

A Megabit is 1,000,000 bits, always has been, always will be. Bits are usually a measure of communcations speeds which are measured in base 10 as opposed to storage which for historical reasons was measured in binary.

Though this is a debate that has been done to death that's the way it is.

[Cheekykid]

A Megabit is 1,000,000 bits, always has been, always will be. Bits are usually a measure of communcations speeds which are measured in base 10 as opposed to storage which for historical reasons was measured in binary.

Though this is a debate that has been done to death that's the way it is.


There was much talk about the upload being too small to support the download speed. I dont know the technical stuff behind but when you download something you also uploading at the same time. Isn't 1.75mbit too small?

[General Maximus]

a couple of weeks ago there were rumours floating around that once it had been fully rolled out it was going to be increased to 2.5 up which sounds more comfortable. I am sure they will try and get out of it if they can.

[cg00759422]

A Megabit is 1,000,000 bits, always has been, always will be. Bits are usually a measure of communcations speeds which are measured in base 10 as opposed to storage which for historical reasons was measured in binary.

Though this is a debate that has been done to death that's the way it is.

i thought a Mega Bit was 1,048,576 Bits ;)

1.5Mbit/s upload is plenty imo means i can host up to a 64 player game now wooo

[dev]

There was much talk about the upload being too small to support the download speed. I dont know the technical stuff behind but when you download something you also uploading at the same time. Isn't 1.75mbit too small?

i *think* you need around 1mbit upload for 50mbit download and people were saying this left next to nothing to upload "proper" data with

i thought a Mega Bit was 1,048,576 Bits ;)

1.5Mbit/s upload is plenty imo means i can host up to a 64 player game now wooo

nope, 20mbit is actually 20,000,000. Internet speeds are done with base 10. In fact you're getting slightly over 20mbit :p:

[General Maximus]

I can't remember how he worked it out but one of the tech dudes on another thread said 1.75 is the bare minimum to sustain 50mbit down. Originiall they tried to get away with 1.5mbit up and it wasn't enough which is why they had to increase it to 1.75. Although even 1mbit up sounds nice by itself (if all you was doing was uploading), you need more upload speed to sustain 50mbit down at the same time (if you was using torrents for example).

[broadbandking]

1.75Mbit is the upload and said before that is the min to get the actual 50Mb

[nutellajunkie]

its all kinda kinky actually, isnt it :)

[Fatec]

I can't remember how he worked it out but one of the tech dudes on another thread said 1.75 is the bare minimum to sustain 50mbit down. Originiall they tried to get away with 1.5mbit up and it wasn't enough which is why they had to increase it to 1.75. Although even 1mbit up sounds nice by itself (if all you was doing was uploading), you need more upload speed to sustain 50mbit down at the same time (if you was using torrents for example).

1Mbit up sounds nice? :erm: 120KB/s but more like 90-110 after overheads when you have 50Mbit down, is nice?

I keep forgetting how UK people enjoy getting ripped off :D

[Milambar]

I was talking to a CCNP friend of mine about this today, I didn't understand his explanation, but its something to do with ACKing each packet, and for 50MB down it really needs about 1.5MB to 2MB up, just to get the full 50MB, before you start uploading any of your own stuff.

[Ignitionnet]

i thought a Mega Bit was 1,048,576 Bits ;)

That would be a Mibibit - 1024 * 1024 bits - Mega = base 10! :)

---------- Post added at 17:09 ---------- Previous post was at 17:08 ----------

I was talking to a CCNP friend of mine about this today, I didn't understand his explanation, but its something to do with ACKing each packet, and for 50MB down it really needs about 1.5MB to 2MB up, just to get the full 50MB, before you start uploading any of your own stuff.

Cable can employ a technique to reduce requirement for ACKing - speak to a CCIE Service Provider - Cable instead :)

[broadbandbug]

I was talking to a CCNP friend of mine about this today, I didn't understand his explanation, but its something to do with ACKing each packet, and for 50MB down it really needs about 1.5MB to 2MB up, just to get the full 50MB, before you start uploading any of your own stuff.

Ask your friend about Ack Supression.. That reduces the amount required in the upstream to achieve the downstream speed.

[cook1984]

Ask your friend about Ack Supression.. That reduces the amount required in the upstream to achieve the downstream speed.

Also ask him about things like protocol overhead, symbol rates etc.

Time and time again tests have shown that 1.5Mb is only just enough to get a 50 meg download speed with one connection on a low-overhead protocol such as HTTP.

Since in the real world this is never going to happen, and besides which 50 meg is supposed to be for multiple users, 1.5 or even 1.75 meg upload is woefully inadequate.

5 meg might be nearer the mark for a reasonable download oriented multi-user connection.

[broadbandbug]

Also ask him about things like protocol overhead, symbol rates etc.

Time and time again tests have shown that 1.5Mb is only just enough to get a 50 meg download speed with one connection on a low-overhead protocol such as HTTP.

Since in the real world this is never going to happen, and besides which 50 meg is supposed to be for multiple users, 1.5 or even 1.75 meg upload is woefully inadequate.

5 meg might be nearer the mark for a reasonable download oriented multi-user connection.

Read this.. This shows why with DoCSIS there are ways to reduce the amount of upstream required to acheive the downstream speeds etc.

http://focus.ti.com/general/docs/bcg/bcgprodcontent.tsp?templateId=6116&navigationId=11893&contentId=4048

[cook1984]

Read this.. This shows why with DoCSIS there are ways to reduce the amount of upstream required to acheive the downstream speeds etc.

Try it for yourself.

Start a download at the maximum speed your BB will allow. Then start an upload and slowly increase it's speed. See at what point your download speed starts to drop. That is the point where the upload, plus a bit of protocol overhead, is choking the connection.

On 20 meg it's at about 15kB/sec. In other words you need about 85% of the available upload bandwidth to maintain a single 2.2mB/sec HTTP download. Extrapolate to the 50 meg service and you will see why they have decided to increase the upstream to 1.75mb.

[Ignitionnet]

Try it for yourself.

Start a download at the maximum speed your BB will allow. Then start an upload and slowly increase it's speed. See at what point your download speed starts to drop. That is the point where the upload, plus a bit of protocol overhead, is choking the connection.

On 20 meg it's at about 15kB/sec. In other words you need about 85% of the available upload bandwidth to maintain a single 2.2mB/sec HTTP download. Extrapolate to the 50 meg service and you will see why they have decided to increase the upstream to 1.75mb.

Minor point, 15kB/s is 1/6th of the available upstream bandwidth on 20Mbps it being 768kbps or about 90kB/s. Extrapolate that to the 50Mbit service it's still less than 400kbps.

[General Maximus]

Just so everyone knows i noticed this years ago and had a bit of a tinker. I havent spent ages playing around to find the magic number, i just picked some random speeds but i find 40k/sec works like a charm for me. Whenever i want to pull my max speed to set my upload limit to 40k (although i think the magic number is around 46) and then i get my 2mb/sec and when my downloads have finished i unleash it again.

[cook1984]

Minor point, 15kB/s is 1/6th of the available upstream bandwidth on 20Mbps it being 768kbps or about 90kB/s. Extrapolate that to the 50Mbit service it's still less than 400kbps.

You misunderstood.

15kB/sec is what is left over. In other words, 90kB/sec - 15kB/sec = 75kB/sec required for maximum speed downloading. That of course includes all overheads so raw monitoring tools will report less than that, but as a fraction of the total available it is correct.

Extrapolate to a 1.5mb upload and you can see that it is only just enough to theoretically max it out. In reality there needs to be a bit more available, hence the move to 1.75mb.

VM's policy seems to be to give you the absolute minimum possible upload speed to max out your available downstream bandwidth. They only bother to advertise the downstream speed.

[General Maximus]

i agree cook, if they really wanted something for everyone to get excited about they would advertise 50mbit down and 5mbit up. The selling point for their products has always been the downstream only.

[Zhadnost]

Give it some time, lets face it, for some of us it's the only hope we've got.

If I were to be more honest, then I wish VM had service in more (especially industrial) areas.

[Ignitionnet]

You misunderstood.

15kB/sec is what is left over. In other words, 90kB/sec - 15kB/sec = 75kB/sec required for maximum speed downloading. That of course includes all overheads so raw monitoring tools will report less than that, but as a fraction of the total available it is correct.

Extrapolate to a 1.5mb upload and you can see that it is only just enough to theoretically max it out. In reality there needs to be a bit more available, hence the move to 1.75mb.

VM's policy seems to be to give you the absolute minimum possible upload speed to max out your available downstream bandwidth. They only bother to advertise the downstream speed.

Quite agree that more upstream would be great but unsure about the amount of upstream you are seeing required for maximum downstream speed.

What are you using to test this? On a single TCP stream I see no more than 350-400kbps being used on a 19-20Mbit download speed.

[Steve-o||[^]]

VM's policy seems to be to give you the absolute minimum possible upload speed to max out your available downstream bandwidth. They only bother to advertise the downstream speed.

Oh, how unattractive it'd be for an ISP to have, next to their amazing "...11 seconds to download a whole album..", how long it'd take you to send..say, video of X's wedding to various family and friends. Note the footnote in such marketing; "1. User must not simultaneously stream crystal clear HD video straight to their computer."