TCP Vegas?

[Crow550]

Worth using?

Heard numerous things on this......Use it with QoS, Don't use it with QoS, use it with Qos & max your outbound rate yet others say set it to zero?


Wha? What?


Anyone use this?

 

[xSauronx]

ive been playing with it, it seems to help, but i have another tomato issue that im not understanding.

i run bittorrent, and play World at War

i classify a port for world at war as High priority (the range of ports it uses is classified as low)
set bittorrent as low (default classified as low)

WaW ports are still classified as low under QoS Details, despite me specifying otherwise /facepalm.

 

[Crow550]

Hrm....If I find a way to solve your issue, i'll let you know. I only set Bittorrent to the lowest & my Wii & Roku to highest.

Well I found using MAC addresses on QOS to not work. However by IP address does. Still confused on TCP Vegas.

Plus are the 3 settings worth tweaking?

I guess I could turn QOS off & Vegas on with default settings for a week. Download some big files & play some flicks on the Roku & see how Vegas handles traffic on it's own.

Really want to know from people who are using it, what works best? As I said in my first post.

 

[xSauronx]

dude you wont even have to test it for a week. leave torrents running, try to game.

turn on vegas, try again. see if its any better.

 

[Engineer]

FWIW, the guy that helped get TCP Vegas into Tomato admitted (at Linksysinfo.org) that it didn't do a damn thing. It was (is?) supposed to be removed from future versions, FWIW.

 

[cmetz]

Crow550, TCP Vegas is a congestion control algorithm for a sending TCP itself. That is, it would only make a difference for connections that originate from your router, NOT for connections that are being forwarded through your router. So it's pretty much useless.

Last I had heard, there are serious questions about whether TCP Vegas is well behaved. It's easy to make a TCP implementation that gets slightly better performance FOR YOU, but when everyone else on a network link does the same thing, everyone (you included) gets less goodput. TCP congestion control is hard.

 

[Crow550]

Ah well thanks. I was just wondering what the heck it was.....

I've been having great luck with Tomatos QOS anyways. I found the trick is to set priority by SRC IP address and not MAC address.

 

[pockets83]

everything with vegas is pretty sweet

 

[Engineer]

From the Linksysinfo forums....

Routers don't do tcp congestion control, even when doing nat. If they did, it would cause unwanted state interactions at each router - just think about tcp slow start happening at every hop! The way any tcp stream reacted would depend on how many routers the packets went thru - the internet would simply not work. Then there's all the cpu cycles you'd need to run the tcp algorithms and all the ram to handle millions of tcp states. That's not what routers do.

For the record, I think Tomato is great, very easy to use - I'm using it right now to send this. I'm just telling you guys that enabling vegas will only affect connections to and from the router - NOT connections that are routed thru, even if you're using netfilter and conntract (which is how tomato does nat).

If you don't believe me, download the linux source and look for yourself.

grep for these fuctions: cong_avoid tcp_rcv_established tcp_v4_do_rcv backlog_rcv ucopy.prequeue sk_receive_skb netif_rx

in these files: net/netfilter/*.c net/ipv4/netfilter/*.c

tcp_vegas_cong_avoid() never gets called by netfilter!