Lagometer discussion

The bottom bar is relatively flat. In a perfect world, it would be completely flat, as well as extremely short. The y axis (up and down) is your ping. The taller it is, the higher your ping. Fluctuating height means your ping is fluctuating. This is entirely normal and can’t be avoided with the Internet. With a ping of 80 ms, it is typical to see between 65 and 95 ms (you can see your ping represented numerically in the top right; /cg_drawfps 1). These fluctuations are visually represented on the net graph by changes in height. As you can see in the above picture, I have a bit of fluctuation. +/15 ms is common for pings under 100; 100-200 will see +/- 25 ms. This is simply due to the fact a higher ping generally indicates the destination server is farther away from your computer, and thus the connection is routed through more servers and switches on its way. These are referred to as hops. The more hops between you and the server, the more opportunities for one or more of the hops to be under high load (which in turn can introduce random spikes in ping). Simply put, the farther the server, the higher the likelihood you will experience unplayable ping fluctuation.

And what’s that look like?

The bottom line is all choppy. I should point out there is no antiwarp enabled on this server. Antiwarp smoothes out ping fluctuations over a certain threshold (default 50 ms). This is not a good thing for you, as antiwarp is designed to make your movement look smooth to other players (ping fluctuations, if severe enough, can induce “warping” which means you player model appears to be skipping around the screen rather than traveling in a fluid motion). Antiwarp can make your gameplay extremely choppy; more so than if it was disabled and you were directly experiencing the hugely fluctuating ping. Essentially you see everyone else as warping, as opposed to them seeing you warping. A reversal of fortunes, so to speak.

I also want to draw attention to the top line of the netgraph. In the previous image, the downward spikes are relatively uniform and evenly spaced. There are no upward facing spikes. Ideally, all the spikes will be the exact same shape and evenly spaced. There will be no spikes facing upward. The previous image is about as good as you will ever see on most servers. The top line is a graphical representation of the server’s “frame rate,” or how it’s doing at sending out 20 “frames” of data per second. All Urban Terror servers run at 20 fps server side. This means they calculate hits, movement, etc. every 50 ms, and send a packet to the client with that data. Fancy client-side interpolation means you see a much smoother game view than 20 fps. However, you only get 20 frames each second of updates…ideally. Sometimes you’ll get less because the server is overworked. The uniformity of the spikes is an indicator of how precise the timing is. Yellow spikes facing upward mean the server was late sending a packet. This can be due to your fluctuating ping (a huge spike will basically interrupt your client receiving the update packet, which is interpreted as the server being late on the netgraph). If, however, your bottom line indicates no spiking (no green spikes, and no thick black areas indicating a spike suppressed by antiwarp), then the server is at fault. Obviously hit detection will be impacted if the server is incapable of running the game at 20 frames per second.

Timenudge can be used to artificially increase the threshold for “late” packets from the server. Notice in the above image, the top line seems to be a bit thicker than in the first image? That’s because ut_timenudge is above 0. Even still there are late packets, but not as “many” as if timenudge was disabled. Timenudge is not recommended, as it delays your world view, but leaves your ping the same. Thus if you set timenudge 20 with an average ping of 80 ms, you will feel as if you are playing with 100 ms, but other players see your ingame model as if it only had 80 ms. Furthermore, if timenudge is necessary to reduce the visibility of upward yellow spikes, you shouldn’t be playing on such a bad server!

That’s what antiwarp looks like. The moderately thick bar near the middle would be felt as a gap in game. Not ideal, but not unplayable. This should not significantly affect hits, as antiwarp is touted as not interfering with hits and shooting, only movement.

This is what you’d see with the second image, if antiwarp was enabled. Completely unplayable, as movement is significantly impaired. I was unable to move properly, and kept crashing into walls because entire key presses were ignored. This has an indirect effect on hits, as enemies warp around and it’s hard to maintain a steady aim when your own movement (at least client-side) is jerky. In this case, the ping fluctuation was caused by my ISP oversaturating their servers.

Each red line signifies a lost packet. Packet loss is quite rare, and the amount seen in the above image is even rarer. This was taken on a server which was apparently experiencing network troubles at the time. You should never see packet loss. Even one or two lines per minute indicates a low quality server, or a problem with the connection. If you see packet loss on every server, it’s your connection.

The yellow bars on the bottom line indicate your packets to the server are delayed. This is because your /rate is too low. For example, /rate 8000 means you can send 8000 bytes of data to the server per packet. If you have more than that amount of data to send, some of it will be delayed until the next packet can be sent (governed by /cl_maxpackets). Simply put your rate to 25000 (/rate 25000) and you will get rid of this problem.

All of the above images, with the exception of the first, show a network condition with will affect how well you can hit in one way or another. Honestly, there’s not much you can do to fix any of those problems besides (with the exception of the last) going to a different server. If you are getting bad hits and your netgraph looks similar to any of the above images, well, you can be pretty sure what the cause of your problem is.