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To: Rob Nelson <rnelson,AT,internoc,DOT,net>, cipe-l,AT,inka,DOT,de
Subject: Re: Quake 3 with cipe
From: Richard Gregory <R.Gregory,AT,liverpool,DOT,ac,DOT,uk>
Date: Sat, 13 Dec 2003 17:40:23 +0000
In-reply-to: <Pine.LNX.4.33.0312101546060.5695-100000@ns1.internoc.com>
References: <Pine.LNX.4.33.0312101546060.5695-100000@ns1.internoc.com>

Tried changing the various Q3 parameters as that guide suggests, the effect was either non-existant, or more bw use. It seems they are optimal enough. For the most part the commands change the incoming rate from the server, rather than from the client. The only command that changed the outgoing rate was com_maxFPS, which is normally 85 but when set to 10 there were an equal rate of incomming to outgoing packets. But, this also means a framerate of 10fps so isn't much use. All this testing was based on a fresh config file.

Ping showed no problems. Ping is blocked somewhere on route, so only the tunnel bound could be tested. ping -f 192.168.8.1 -s 150 -t 0.0001 came back with this:
PING 192.168.8.1 (192.168.8.1) from 192.168.7.10 : 150(178) bytes of data.
...
--- greg ping statistics ---
618 packets transmitted, 615 received, 0% loss, time 9252ms
rtt min/avg/max/mdev = 35.200/39.797/49.705/3.123 ms, pipe 5, ipg/ewma 14.995/43.049 ms


192.168.7.10 being the dual boot machine, 192.168.8.1 is the Q3 server and cipe endpoint. As you can see, there is no continuous loss, these three lost packets were at the beginning. These packets were larger and at a higher frequency than Q3 in either OS.

Looking at the net traffic in ethereal, the extra packets coming from Q3 in XP are not retransmits, as each is very different. Besides the number of packets they are no different from the Linux Q3 client. Q3 in XP outside the tunnel to the same Q3 server continues to send/receive at the same rate.

So at the end of all this, still no clues...

Richard

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Rob Nelson wrote:
Sorry, I misread the original. I just went and took a look at the quake3
config file options here:

http://www.planetquake3.net/tweak/glossary_commands.html

I would definitely _not_ try to run quake3 on the same machine in XP and
linux with the same config file. On the same exact hardware, I believe
linux to be considerably faster for most operations. XP has a considerable
amount of more overhead in the os, and especially in the network protocol
stack.

You might compare packet loss ratios between the configurations with ping
blasts, or maybe with netcat - XP->linux native pipe, same over cipe, and
linux->linux over both. At some transmission rate you will experience
packet loss.

I would go tweak some of the connection settings on the XP instance based
on the experiences above, compensating for XP's lag. Even a small amount
of difference in the latencies of the stack can cause large amounts of
retransmits. It also seems that when you have the above conditions, AND no
variation in the traffic pattern the problem is greater than expected. You
may find that dumping some traffic with larger average packet sizes on the
cipe network will smooth out the traffic flow.

If it was tcp we would tweak these things in the protocol stack, if its
udp they're tweaked in the application.

On Wed, 10 Dec 2003, Richard Gregory wrote:


Erm yes, that is why the third paragraph of my original message said this:
Some background... Quake does most of its communications using UDP port
27960. The game server sends packets out representing the current state
of the game at a rate of around 25 per second, ~100 bytes each to port
27960. The clients send back packets representing the users actions, at
around the same rate, size and the same UPD port.

As you can see, this isn't TCP at all, it is basic UDP. So why does
XP/Q3 create those extra packets??


Richard


+--                               --+
|    Computer Science, Room G34     |
|  http://www.csc.liv.ac.uk/~greg   |
| Electrical Engineering, Room ~104 |
+--                               --+

Rob Nelson wrote:
>
> On Mon, 8 Dec 2003, Richard Gregory wrote:
>
>
>>Noticed a problem with Quake 3 network traffic when routed over cipe.
>>Quake 3 sends four times as many UDP packets to the game server as it
>>does when outside the tunnel (or in a ssh/pppd tunnel). This problem
>>only happens when the Quake3 client runs on an XP machine, reboot into
>>Linux and the packet rate becomes one-to-one.
>>
>>This is still the case when the Linux Q3 config file is copied over the
>>Q3 XP config. All in all, suggesting some sort of interaction problem
>>with cipe and XP, but I've no idea what.  Does anybody have any
suggestions?
>
>
> What protocol is quake running? There are differences in how the tcp/ip
> stack is configured on linux and windows. Knowing whether quake runs udp
> or tcp would help to configure it. Are there any  differences in the
> packet trace besides the XP client's extra chatter?
>
>
>
>
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