[oka5]

what do the s and r stand for that are at the top right screen.

[LadyKiKi]

Send
Recieve

(I think)

[Kittyneko]

Yes, or in other words, your Upload and Download rate.

You'll disconnect if either of them goes to 0.

[LadyKiKi]

From what I've noticed, if R is 0 you might disconnect, unless it goes back up again.

If S is low (under 100), you might experience more lag than usual. This is more evident in a shared house/connection, as other people might be uploading/P2Ping, causing this to happen
If R is high (1000+), you're in a busy area. Likewise, if low (sub 200), you're not in a busy area.

[Feba]

S, send, how much data you're transmitting (upstream).
R, how much you're receiving (downstream).

Them hitting 0 for a second or two isn't exactly good, but you shouldn't disconnect unless R stays at 0 for an extended amount of time (which indicates that you have stopped receiving information from the server). This is why the red circle of death (We had it first, dammit, Microsoft always ripping other people off) is often called simply "R0".

They will change wildly depending on what you're doing. Mainly, the more stuff is in the area you're in, the higher R will be. For example, walking around the middle of nowhere, it will be pretty low, walking around a city it'll be higher, the highest is when you're surrounded by mobs (such as if you or someone else nearby has a train of mobs linked together.). Personally, I've gone about as high as 5000-6000 doing that. Really, though, your client is probably going to have problems far before your connection does.

Really, you only need to pay attention to them when the world seems to stop moving. If nobody around you is moving, monsters don't attack and such, you can check it and see if it's at 0, which would be why you aren't getting information. Other than that, it's pretty much useless.
______________________________
blech, damn you lack of telepathy.

[Kittyneko]

If you're experiencing lag, you can go all the way down to 0% (R0/S0) for a while, and eventually going back up before you time-out.

If your connection is re-initialised, you will disconnect, this is because of the UDP protocol the ffxi servers use.. I think.


Useless info from what I know:
UDP protocol uses up less broadband for more data, but it's less safe because the server doesn't say when packages are missing. The opposite to UDP is TCP.

Also, I believe newer MMORPG's (such as WoW) use a combination of UDP and TCP, namely UDP for server info, and TCP for game data.