TCP Vegas makes QoS unnecessary?

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p00nka
DD-WRT Novice


Joined: 31 Oct 2006
Posts: 10

PostPosted: Tue Mar 11, 2008 15:58    Post subject: TCP Vegas makes QoS unnecessary? Reply with quote
I have been struggling with my Cable Modem internet connection to minimize packet loss & packet delay when uploading at full, uncapped speed.

Up until now, I had been using QoS to cap my upload, as the docs say, to 90% or so of my maximum upload. This requires me to accurately determine what my maximum upload rate is, and thanks to comcast & speedboost, this varies quite a lot.

Then I discovered TCP Vegas congestion control. According to wikipedia, TCP Vegas tunes the network performance based on packet delay instead of packet loss. Sweet! So I disabled QoS, enabled tcp_vegas, and played with it a bit. These options in the firewall commands have made all of my packet delay problems disappear! I see ~50ms pings while uploading even after speedboost has worn off.

Code:
echo 0 > /proc/sys/net/ipv4/tcp_westwood
echo 1 > /proc/sys/net/ipv4/tcp_vegas_cong_avoid
echo 3 > /proc/sys/net/ipv4/tcp_vegas_alpha
echo 3 > /proc/sys/net/ipv4/tcp_vegas_beta


Anyone else wanna give it a try and see if it works for you as well? From what I can tell, it plays very well with cable modems & speedboost.
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dicksons
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Joined: 07 Jun 2006
Posts: 980
Location: Coal Creek Canyon, Colorado

PostPosted: Tue Mar 11, 2008 16:50    Post subject: Reply with quote
on what device did you enable this (computer? DD-router ? Cable modem ?) and how did you do that ?
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p00nka
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Joined: 31 Oct 2006
Posts: 10

PostPosted: Tue Mar 11, 2008 18:51    Post subject: Reply with quote
I did this on my dd-wrt v24 RC3 enabled Linksys WRT54GL router. I believe that dd-wrt has always supported multiple tcp congestion control algorithms. This is a module in the linux kernel. By default, dd-wrt uses tcp_westwood while openwrt uses bic.

1) Click Administration
2) Click Commands
3) Enter the code above
4) Click "Save Firewall"
5) Reboot router

(edited to correct v24 RC not SP)
dicksons
DD-WRT Guru


Joined: 07 Jun 2006
Posts: 980
Location: Coal Creek Canyon, Colorado

PostPosted: Tue Mar 11, 2008 19:30    Post subject: Reply with quote
Ok -- thanks I re-read your first port more closely and it makes sense.

I wonder if this is only effective in a routed configurations -- would this do any good for a client-bridged or an AP-only ?

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alain
DD-WRT Guru


Joined: 06 Jun 2006
Posts: 601

PostPosted: Tue Mar 11, 2008 19:35    Post subject: Reply with quote
That sounds very interesting!

Is there any possibility of using qos (to priorize services) together with congestion control?
DgtHorse
DD-WRT Novice


Joined: 15 Aug 2007
Posts: 10

PostPosted: Tue Apr 15, 2008 3:30    Post subject: Re: TCP Vegas makes QoS unnecessary? Reply with quote
p00nka wrote:
I have been struggling with my Cable Modem internet connection to minimize packet loss & packet delay when uploading at full, uncapped speed.

Up until now, I had been using QoS to cap my upload, as the docs say, to 90% or so of my maximum upload. This requires me to accurately determine what my maximum upload rate is, and thanks to comcast & speedboost, this varies quite a lot.

Then I discovered TCP Vegas congestion control. According to wikipedia, TCP Vegas tunes the network performance based on packet delay instead of packet loss. Sweet! So I disabled QoS, enabled tcp_vegas, and played with it a bit. These options in the firewall commands have made all of my packet delay problems disappear! I see ~50ms pings while uploading even after speedboost has worn off.

Code:
echo 0 > /proc/sys/net/ipv4/tcp_westwood
echo 1 > /proc/sys/net/ipv4/tcp_vegas_cong_avoid
echo 3 > /proc/sys/net/ipv4/tcp_vegas_alpha
echo 3 > /proc/sys/net/ipv4/tcp_vegas_beta


Anyone else wanna give it a try and see if it works for you as well? From what I can tell, it plays very well with cable modems & speedboost.


Wow! this is actually the ONLY solution that works perfectly for me!
Thanks p00nka
olmari
DD-WRT Guru


Joined: 24 Oct 2006
Posts: 1447
Location: Finland

PostPosted: Tue Apr 15, 2008 12:14    Post subject: Reply with quote
Hmm, I think this might actually be something even developers themselves didn't realise existing in DD-WRT :p
redhawk0
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Joined: 04 Jan 2007
Posts: 11564
Location: Wherever the wind blows- North America

PostPosted: Tue Apr 15, 2008 13:17    Post subject: Reply with quote
I am testing this with FiOS right now....so far...this is a very promising alternative to QoS.

My 35MByte download is at 86Kbps and my FiOS download is running 4-5Mbps normally with no "pixilized" image or freezing.....looks good.

I'll include this as a possible solution to the FiOS setup in the wiki.

http://www.dd-wrt.com/wiki/index.php/Verizon_FIOS_setup_with_dd-wrt_as_primary_router

In step 11 I included some links regarding the tcp_vegas protocol.

thanx p00nka

redhawk

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redhawk0
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Joined: 04 Jan 2007
Posts: 11564
Location: Wherever the wind blows- North America

PostPosted: Tue Apr 15, 2008 15:12    Post subject: Reply with quote
Has anyone tried tcp_vegas using DSL, PPPoE, PPTP...etc?

My FiOS is similar to Cable Modem setup. (Auto DHCP) so my experience so far as been the same as the OP.

redhawk

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DgtHorse
DD-WRT Novice


Joined: 15 Aug 2007
Posts: 10

PostPosted: Tue Apr 15, 2008 15:20    Post subject: Reply with quote
redhawk0 wrote:
Has anyone tried tcp_vegas using DSL, PPPoE, PPTP...etc?

My FiOS is similar to Cable Modem setup. (Auto DHCP) so my experience so far as been the same as the OP.

redhawk


Im using it with DSL (PPPOE) and works like a charm. i also have QoS enabled though and it works great!
redhawk0
DD-WRT Guru


Joined: 04 Jan 2007
Posts: 11564
Location: Wherever the wind blows- North America

PostPosted: Tue Apr 15, 2008 15:31    Post subject: Reply with quote
DgtHorse wrote:

Im using it with DSL (PPPOE) and works like a charm. i also have QoS enabled though and it works great!


So you are using both at the same time. Have you done any tests with just the tcp_vegas alone?

I only enabled the tcp_vegas without QoS and my FiOS definitely has higher priority over downloading files.

[EDIT] - I guess priority isn't the right word here...I get constancy in my VoD downloads would be a better way to put it.

What are you using QoS for?

redhawk

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DgtHorse
DD-WRT Novice


Joined: 15 Aug 2007
Posts: 10

PostPosted: Tue Apr 15, 2008 15:35    Post subject: Reply with quote
redhawk0 wrote:
DgtHorse wrote:

Im using it with DSL (PPPOE) and works like a charm. i also have QoS enabled though and it works great!


So you are using both at the same time. Have you done any tests with just the tcp_vegas alone?

I only enabled the tcp_vegas without QoS and my FiOS definitely has higher priority over downloading files.

[EDIT] - I guess priority isn't the right word here...I get constancy in my VoD downloads would be a better way to put it.

What are you using QoS for?

redhawk


I used TCP vegas alone, everything ran like a charm but BitTorrent and web browsing were both slow, VOIP was great. Enabled QoS (HTB) and set my bandwidth to 80% available and web/VOIP worked fast! The Bittorrent downloads were slowed to a crawl but thats what i wanted! Smile
Eko
DD-WRT Developer/Maintainer


Joined: 07 Jun 2006
Posts: 5771

PostPosted: Wed Apr 16, 2008 9:13    Post subject: Reply with quote
Interesting....
SEA
DD-WRT Novice


Joined: 22 Sep 2007
Posts: 20

PostPosted: Wed Apr 16, 2008 22:23    Post subject: TCP Vegas makes QoS unnecessary? Reply with quote
I try this too. Seems to be good thing!
It works, but i'm not sure yet if i need QoS. I turned QoS off (used primary for voip). I will see if vegas alone is enough.

My concern about using vegas and QoS - they would be conflicting if used simultaneously for trafic controlling. Any ideas?
dicksons
DD-WRT Guru


Joined: 07 Jun 2006
Posts: 980
Location: Coal Creek Canyon, Colorado

PostPosted: Thu Apr 17, 2008 3:19    Post subject: Reply with quote
back to my question -- is this applicable to AP-only ? or only in a routed config ?


viva... Viva... VIVA!!!

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