Confused about download speeds

D

dderidex

Supreme [H]ardness
Joined
Oct 31, 2001
Messages
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Okay, here is the thing. I have ALWAYS selected '256kbps DSL' when setting up programs - STEAM, Torrent clients, etc - as I have never gotten more than that downloading.

EVER.

Filefront, Fileplanet, Gamespot (with premium account), Torrents set higher (I even tried uncapping it once) - ALWAYS right around 256kbps.

Now, I have Comcast cable, and that shouldn't be right, but I always just chalked it up to crappy service and dismissed it - I didn't really need more than 256kbps, anyway.

However, I just did a test on dslreports.com, and my speeds are showing:



...so I tried downloading a demo from Gamespot and Filefront again, and...nope, still 256kbps. Just bumped my Steam settings up to "Cable/DSL > 2mbps", and tried downloading the Medieval II demo....at 200kbps. Huh?

I can't even watching streaming videos at 700kbps without stuttering and frame drops.
 
It's called "PowerBoost" and you can get more info at:

http://www.comcast.net/help/faq/index.jsp?faq=ServicesPowerBoost18502

Short-term high burst rate speed bumps, and on speedtests it can typically exaggerate the speed you actually have because the speed burst lasts longer than the speedtest itself, so... you end up with the kinds of results you have there. :D

I'm on a 10/1 connection and I regularly get speeds like this:

142025896.png


and I've had peaks of 34 Mbps actually depending on the time of day. It only lasts a few seconds, and the idea is that people tend to download smaller files more often, so burst it and get it to them faster so the network can move on to other data for other people. Not good for long huge downloads, but even so, it does work at the beginning. Just ran the test again, same server, just after 12:24PM and it shows:

149792633.png


Hope this helps...
 
Hmmm....that would, indeed, explain quite a bit.

Any way to find out the actual speed you are getting for sustained downloads? And when they sell the package, are they selling it at the 'burst' rate or the sustained rate? (My understanding is that we have a 6mbps/384kbps line, so bursting at 3mbps only for a few seconds is...rather teh suck)
 
dderidex said:
Hmmm....that would, indeed, explain quite a bit.

Any way to find out the actual speed you are getting for sustained downloads? And when they sell the package, are they selling it at the 'burst' rate or the sustained rate? (My understanding is that we have a 6mbps/384kbps line, so bursting at 3mbps only for a few seconds is...rather teh suck)
Click to expand...
Are you using a very old router? If so, that could be limiting your speeds.

Comcast's 6Mbps plan will burst up to 35Mbps for the first 10Mb of a file, so the throughput you are seeing is lower than it should be. Still, 6Mbps translates to 768 kilobytes per second, and it doesn't look like you are seeing anything close to that.

First, I would suggest running the tweak test @ DSLReports: http://www.dslreports.com/tweaks

If you can, copy and paste the results here, especially your 1) Receive Window, 2) Window Scaliing, 3) RFC1323 Window Scaling, 4) MSS requested, and 5) transfer rate.

Try downloading some 720p trailers from Dave's Trailers and see what sort of throughput you get.

Write down your results. If PowerBoost is working correctly, you should see high throughput for the first 10 megabytes and then it should drop to 6Mbps (768Kbps).
 
KenF said:
Are you using a very old router? If so, that could be limiting your speeds.

Comcast's 6Mbps plan will burst up to 35Mbps for the first 10Mb of a file, so the throughput you are seeing is lower than it should be. Still, 6Mbps translates to 768 kilobytes per second, and it doesn't look like you are seeing anything close to that.

First, I would suggest running the tweak test @ DSLReports: http://www.dslreports.com/tweaks

If you can, copy and paste the results here, especially your 1) Receive Window, 2) Window Scaliing, 3) RFC1323 Window Scaling, 4) MSS requested, and 5) transfer rate.
Click to expand...

Router is Netgear WGR614v6, PC is on a Wireless-G connection to it. Modem is a D-Link model of some kind. DCM-202, IIRC?

From that test:

Receive Window (RWIN): 17520
Window Scaling: off
Path MTU Discovery: ON
RFC1323 Window Scaling: OFF
RFC1323 Time Stamping: OFF
Selective Acks: ON
MSS requested: 1460
TTL: unknown
TTL remaining: 113

Actual data bytes sent: 1029841
Actual data packets: 707
Max packet sent (MTU): 1500
Max packet recd (MTU): 1500
Retransmitted packets: 4
sacks you sent: 42
pushed data pkts: 168
data transmit time: 7.763 secs
our max idletime: 208.9 ms
transfer rate: 127141 bytes/sec
transfer rate: 1017 kbits/sec
transfer efficiency: 99%
 
dderidex said:
Router is Netgear WGR614v6, PC is on a Wireless-G connection to it. Modem is a D-Link model of some kind. DCM-202, IIRC?

From that test:

Receive Window (RWIN): 17520
Window Scaling: off
Path MTU Discovery: ON
RFC1323 Window Scaling: OFF
RFC1323 Time Stamping: OFF
Selective Acks: ON
MSS requested: 1460
TTL: unknown
TTL remaining: 113

Actual data bytes sent: 1029841
Actual data packets: 707
Max packet sent (MTU): 1500
Max packet recd (MTU): 1500
Retransmitted packets: 4
sacks you sent: 42
pushed data pkts: 168
data transmit time: 7.763 secs
our max idletime: 208.9 ms
transfer rate: 127141 bytes/sec
transfer rate: 1017 kbits/sec
transfer efficiency: 99%
Click to expand...
No wonder. Your receive window is way too small and you have window scaling disabled. That's a recipe for low throughput.

Download TCP Optimizer here.

general_settings.png


To start, I would use a receive window of 64240 and enable Window Scaling. Both options are on the General Settings tab.
 
KenF said:
No wonder. Your receive window is way too small and you have window scaling disabled. That's a recipe for low throughput.
[...]
To start, I would use a receive window of 64240 and enable Window Scaling. Both options are on the General Settings tab.
Click to expand...

That was mentioned on a thread I made on dslreports, too.

How do those settings effect traffic, though? What kind of real-world differences would these make?
 
dderidex said:
That was mentioned on a thread I made on dslreports, too.

How do those settings effect traffic, though? What kind of real-world differences would these make?
Click to expand...
It can increase your throughput by 800% or more.

The default settings in Windows 2000/XP are intended for 768Kbps DSL. That is what you are using now. If you have something better than that, then you need to change the settings.

Run, not walk, to make the changes. There is no downside. For comparison purposes, run a Speakeasy's speed test. Then make the change, reboot, and run the same speed test again.
 
Alright, testing now.

EDIT #4: I made the above changes to my wireless adapter, rebooted, and tested again. I did the same test on my 'untweaked' fileserver. Puny little Pentium II (yes, 2) 233mhz box with 384mb of ram. BUT...it has a 10/100 connection to the router. And, while that turtle was rebooting, tested my wife's laptop (untweaked).

Results in nice, table form.

From this site, to Seattle, WA, I read:

Code: 
			My PC		Wife's PC	Fileserver

Download 	Orig	4742 kbps 	4645 kbps	7247 kbps
		Tweak	4810 kbps	4853 kbps	7327 kbps

Upload 		Orig	282 kbps 	364 kbps	357 kbps
		Tweak	283 kbps	364 kbps	362 kbps

I think, from the above testing, I can tell two things:
  • Something seriously sucks about Wireless-G. I'm getting less than 2/3 of the throughput through the Wireless adapters as I am through the 10/100 adapter. That's insane, as the throughput I'm getting is WAY less than half what Wireless-G should be able to handle.
  • The suggested tweaks really make no difference at all. On three machines, with three diffent brands of adaptes (Zydas Wireless, Broadcom Wireless, Netgear 10/100), they made no difference outside of the margin of error for the test.
 
Plug the first 3-4 digits of your zip code into this page to see what throughput others in your area are getting on Comcast.

http://www.dslreports.com/archive

As you say, it looks like wireless is limiting you to around 4800Kbps.

At full 54Mbps wireless sync, you should be able to do 20-22Mbps via wireless. At the very minimum, you should see just as much throughput as you do on that old wired server. Based on your results, it sounds like your wireless PCs are sync'd at closer to 12Mbps, of which about 7Mbps is consumed by network overhead (leaving ~5Mbps usable). Unfortunately, not all routers will tell you what wireless speed you are synced at. Most wireless NIC drivers also report 54Mbps in Windows, regardless of your actual sync speed, so that doesn't help either.

I'm going to assume you've already rid yourself of 2.4GHz cordless phones and 2.4GHz wireless video systems, as well as any Bluetooth wireless keyboards and mice using the 2.4GHz band. That's the first step to eliminate interference with your 802.11g network. Of course, if you live in an apartment or condo, you're still subject to the interference caused by your neighbors.

If you are sync'n at significantly less than 54Mbps, then that would suggest either a weak signal or a lot of interference in the 2.4Ghz band. With most drivers, Windows XP will report 54Mbps anytime that you connect with 802.11g. However, that has nothing to do with the actual sync rate.

The below screenshots are a perfect example.

Wireless sync with 2.4Ghz wireless video system on

The x.x.x.112 system is the Playstation3 in my living room. The x.x.x.102 is a PC in an office downstairs. That particular office has a lot of RF interference when certain equipment is on. I turned that equipment on for the above screenshot, and XP showed 54Mbps with signal strength of 4 bars. But look at the actual sync speed, as reported by the D-Link router. The wireless errors reported on the D-Link's status page increment regularly.

The below screenshot is with that equipment turned off. The signal strength is similar, and Windows reports the same 54Mbps, but the actual sync speed is very different. Wireless errors, as reported on the D-Link's status screen, are largely eliminated.

Wireless sync speed with 2.4Ghz wireless video system off

I live in a suburban neighborhood, so there is a fair amount of distance between my home and the next. Hence, interference from other peoples' 2.4GHz devices, such as cordless phones, cordless mice/keyboards, wireless video cameras, and the like is kept to a minimum. If you live in an apartment complex, there is almost certainly more interference in the 2.4GHz spectrum, even if you see only one or two 802.11g networks. Also remember that Windows will only show wireless networks that broadcast their SSID; many enthusiasts disable their SSID broadcast for security reasons.

If you are using Windows XP, the first thing you should do is download and install Netstumbler. It will tell you what wireless channels are in use around you, so you can set the Netgear WGR614v6 to use a channel that will minimize interference.

http://www.netstumbler.com/downloads/

Once you've determined what wireless channels are in use, set the Netgear to use a channel farthest from those. Refer to the graph below:

channeloverlaprr8.jpg


While you're at it, you might want to download the latest drivers for your network adapters below. It is possible that a newer driver will display your 'true' wireless sync rate, rather than the standard 54Mbps BS.

http://www.station-drivers.com/
 
The latest drivers for my particular adapter (it's a Shuttle WiFi adapter) are likely not there, but there are newer ones than I'm using from the manufacturer. However, that my wife's laptop sees the same thing makes me think the answer is not just drivers.

I'll try that Netstumbler app - I wondered if there was an easy way to find an open band. I live in a major metro area, nearly IN town, and there is a lot of wireless traffic in my area. My wireless adapters shows 7 SSIDs being broadcast around me, although only 3 (including mine) are over 50% strength.

I also do not use Window's 'Wireless Zero Config' settings, but the control panel that ships with the wireless drivers I use. I generally see 100% signal strength and 75%+ link quality.

EDIT: Now, that Netstumbler IS interesting. Based on that, and your above graph, I was able to see that every channel in my area was covered, generally by more than 1 adapter, from one end to the other. Except 11. It was only 50% covered (someone is using channel 9). I set it to '11', and tested again:

Code: 
			My PC		Wife's PC	Fileserver

Download 	Orig	4742 kbps 	4645 kbps	7247 kbps
		Tweak	4810 kbps	4853 kbps	7327 kbps
		#11	5999 kbps
		Flashed	7707 kbps	7701 kbps	7765 kbps

Upload 		Orig	282 kbps 	364 kbps	357 kbps
		Tweak	283 kbps	364 kbps	362 kbps
		#11	365 kbps
		Flashed	364 kbps	364 kbps	364 kbps

FINAL EDIT...Now THAT is what I call an improvement! Changing the channel made a difference, but flashing to the latest firmware on the router (shipped 1.0.6_1.0.5 to latest 2.0.19_1.0.19) made a HUGE difference. In response to my first post, using the same server as that test, I'm now seeing:



So...definite improvement.
 
Amazingly, a firmware update to the router seems to have made the BIGGEST difference.

I'm now close to double the speed I had before. Additionally, while that speed was all the more it had, when running tests now, it tops 13mbps for a few seconds before dropping down to the ~7mbps range. And all three devices - both wireless, and the wired device - are now seeing the same throughput, rather than the huge difference between wired and wireless.

This is GOOD.

Bizarre that there is no mention in ANY of the firmware release notes about any kind of performance improvement, or issue resolve with the Wireless, or anything. But, in practice, it damn near doubled my throughput.

This is nice!
 
dderidex said:
Bizarre that there is no mention in ANY of the firmware release notes about any kind of performance improvement, or issue resolve with the Wireless, or anything. But, in practice, it damn near doubled my throughput.
Click to expand...
So you are now maxing out at 13Mbps, even after you tweaked the LAN box? That may be the maximum routing speed supported by your Netgear. Comcast PowerBoost will do up to 30-35Mbps during off-peak hours in many areas (for the first 10 megabytes of a connection), so you may want to consider upgrading and/or trying a different router.

I would suggest the Buffalo Technology WHR-G125, on sale for $25 after rebate at Circuit City. That will route at over 20Mbps.
 
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