Artificially high ping and packetloss

I visited my brother this weekend and he was telling me about how he had recently got an SL account, but that he was suffering from significant "lag". Based on the symptoms he was desscribing it sounded like a high ping-time between him and the servers.

So after dinner we fired up SL so I could show him how to determine what the problem was.

First, I told him to hit ALT+1. (This toggles on/off some stats in the upper right corner of the window. It is much like a menu in that the items can be expanded/collapsed by clicking them with the mouse. Each category has several fields that have three display modes -- click with the mouse to rotate through the modes.)

Then we looked at the "sim ping" field near the bottom of the top category. It was showing about 450 msec (half a second!) which seemed too high for his connection.

Looking up at the far right of his menu bar I noticed that his packetloss indicator was in the red-zone. (This is a little unabled bar that is always visible in the far upper right corner of the SL window. There are actually two little bars -- one is network bandwidth (right) and the other is packet-loss (left). Hovering the mouse over the bars for a second or two will produce a tool tip that gives more information about them.)

Lots of packet loss usually means that the amount of bandwidth that SL is trying to use is beyond the capability of the connection. That is, there was some piece of hardware between his computer and the SL servers whose packet buffer is filling up, and it therefore either stops accepting more packets, or pushes old packets off the queue. The particular hardware was probably part of his ISP's infrastructure since he had earlier witnessed SL without such "lag".

The fix is to go into the preferences and set SL's default bandwidth to something lower than the default 500 kbps. For my brother we dropped it down to 200 kbps, and we also brought in his view-distance to the minimum of 64 meters, which reduces the amount of data requested from the servers. (This may have been too much, but he can now play with these numbers to find out what his system/network can handle.)

His problem was solved -- packet-loss dropped to almost zero and his movement in the world was much more responsive.

Now if only muting sound would kill the wasted bandwidth from 200-300 incoming audio streams at once

Damn you jukebox people!

I fully endorse this product or service!

Wouldn't it make sense to have SL make this adjustment automatically?

I had to do a fresh install of SL the other day when the latest version kept crashing at start-up. Someone suggested I set the bandwidth lower and when I did I noticed that the box next to 500 was checked, even though the box marked 300 had "default)" by it.

Regardless of what the actual default is however, how hard would it be for the client to throttle back this setting whenever packet loss became extreme?

My understanding is that while DSL users get a certain amount of guaranteed bandwidth, cable modem users share bandwidth with their neighborhood and can have fairly large fluctuations, hence it would be nice if that setting could automatically vary itself up, as well as down, as conditions changed.

Partially true, but as always, simply depends on the ISP. DSL users are guaranteed bandwidth between their house and the ISP's physical location. After that, it's shared, just like cable, so both DSL and Cable can slow down if the shared portion is not managed properly. As long as the cable provider allocates enough nodes (clusters of shared connections) for their user base, there's no problem. I've never really noticed a slowdown on my cable connection, though I suppose I don't really know who else is on my node.

Just thought I'd add that little tangential tidbit.

Does this number limit my upstream or downstream? I've never had a problem with too much downstream bandwidth causing packetloss. My upstream is really small though. If I upload any size file over FTP or run kazaa I get horrible horrible PL.

Can we have seperate limits for up/down?

It actually does not make sense for SL to automatically compensate for this.

Overutilization of available bandwidth is only one cause of packet loss. There can be actual network failure conditions which will result in packet loss, which are NOT the result of a degradation of available bandwidth.

Basically, you may have 1MB of available bandwidth, and be dropping 20% of packets due to a bad cable. Retraining your speed down to any level will not likely correct the problem, though it may be less noticable. If SL were to automatically try to correct for this, it would reach 0 before being able to correct the loss.

The default settings are pretty conservative and should work for almost everyone. It would be rare for a decent high-speed connection to not have 300kbit/sec of downstream available in most circumstances.

So very glad I'm not the only one who thinks that. Cheers!

Is that an endorsement of a better muting solution or the damnation of jukebox people or both?

Hi,

since this thread is about bandwith, I got a question, hopefully someboday can answer it.

I'm rather new to SL, but not very new to online games, in fact, I'm busy with them to get a pay check every now and then...I write that, because I really wonder about the immense amount of data that is constantly going in and out.

Right now it's noon GMT, the world is nearly empty, and my AV stands alone with nobody visible on the minimap.

After standing for a longer time to load all textures, I got an bandwith of around 50-60 kbps. Without doing or moving anything.
What are those 50-60kbps, actually I have no clue why I receive so much data from the server when absolutly nothing happens.

Oh, and as a sidenote, to compare data ammount, a game like Shadowbane is using normally less than 1kbps. I don't compare games here, or the style server archicture works with resources, but SL usally neds at least 100 times more kbps than other online games, under best circumstances it's still 50 times more.

Can somebody enlighten me?

greets,

Kelly

Comparing SL to a static world like Shadowbane is really comparing apples to oranges.

When you installed Shadowbane, everything in the world was written to your hard disk. Very little of the world will change as you play the game, other than the people and characters who move about.

In SL, *everything* can change at any moment. This means the world always needs to be downloaded whenever there are changes. This even includes the position of the sun, the cloud cover, speed and direction of the wind, ambient sounds, simulator metadata, object position/rotation updates, etc. All this can be happening even while it looks like nothing is happening.

Finally, be sure not to get network data rate units crossed.

Shadowbane may report "1kbps", but they could potentially be reporting kiloBYTE per second. This is normally accepted as being expressed with a capital "B" for byte, but often people make the mistake of using lower case.

SL's units are in kiloBIT per second.

Yes, SL does use a lot of bandwidth. But that's the tradeoff you have to make for a fully dynamic world.

Hi Kex,

sorry, I said I don't compare the games, i Just compare the data. I agree to what u said, but please read my posting carefully.

Everything in SL is temporary stored, yes, but after all data was cached on my machine, as I said, what are the 50-60 when all is downloaded?

As long as nothing changes the bandwith should go down to a very very small amount, but it doesn't.

=D

Hi,

so you are saying that lighting is NOT done by client side?

Means, for example, a gleaming, turning ball, would send constant updates from server to client depending on the situation the light/shadow is at that very moment. Please say that I am wrong here.

I believe the right question to ask would be, do we CARE about the changes?
Do most people actualy need the most current sun, wind, and cloud positions?
Does anyone care if their neighbour is building something in his basement, forcing you to download crap you will never see?
I know you americans dont pay for bandwidth but this is ridiculous.
I think some sort of feature to limit the downloading of sounds would be a very good start.
Given that chat only spreads for 20 meters, being able to turn the draw distance down to 32 would be a nice start.
What a lot of people actually want is the option to restrict draw distance/chat spreading to the current plot for the purpose of privacy. This has been requested more than once in the past, but it sounds harder to do given that plots can have an arbitrary size and shape which can also change at any time.

Kelly, you can turn on the debug console and watch what is happening. Lots of things keep downloading after it it looks like everything is loaded. (textures, sounds, etc)

Hi,

for me it's less a cost factor Eggy, I simply often work while I'm ingame. Often I need to upload/download some stuff, but with SL running my first reaction was like wtf...and I checked all kind of stuff on my machine, until I figured that SL seems to block around 50% of my bandwith while playing.

Not everybody got a 2GB cable connection.


Edit: I did turn on the whole debug console (alt 1) if u mean that. And I was watching it very closely, and checked what happend when I moved, created a prim, or just did nothing. I tested a bit around with it, and what confused me most is, that fooling around with prims and textures has very little impact on it, while other datas seems to increase the amount tremendous.

HEY ANDREW:

DOES THAT OPTION CONTROL DOWNSTREAM / UPSTREAM OR BOTH?

I have no downstream limit but if I max my upstream I get really bad PL.

A turning ball can be either client side or server side updates, depending on what method of rotation is used.

Turn on your debug menu, with Ctrl-Alt-Shift-D

Select "Show Updates".

You'll then see an indicator eminating from any object which is being updated.

In an empty sim, with just me, I get about 5-8kbps of "idle" usage. One of the Alt-1 debug screens breaks bandwidth usage down into the segments that the Network prefs does, Land, Objects, Wind/Water, Textures/Sound I think. Under most normal world conditions the textures stream is the most active, due to the many different textures in builds and on avatars. Like Kex said, the "Show Updates" will let you know if things are updating all the time, probably via script. There's one sim where a certain club was running probably 50 scripts updating their objects, either the floating text, rotating pictures, or both. The idle bandwidth there is around 70kbps if I remember right.

In most sims with static builds my idle bandwidth averages around 30kbps, and up to 70kbps in highly dynamic ones.

As for packet loss, I've noticed it a lot more lately, no matter what my bandwidth is set for. I regularly run with it set down to 100kbps (I'm paranoid about affecting my SLive stream) and get loss even then in some situations.

I checked the area again, the Maroon Mall btw, I found no object that is constantly updating, although I might have missed some in hidden rooms.

No further updates were shown in the advanced Alt-1 screen for textures.

Objects seem to upload constantly, so I guess I missed some object that sends constant updates but it was not visible to me. So the question still stands for me.

But while I look at it...that leads me to another question (yes, I know, it never stops ), the packet in/out counter....
While the kbos change between a factor of 1-5, the packets in change only between a factor 1-2. huh? Shouldn't it use the same factor in coherency with the amount of data transfered???

Packets out are always between 20-50 packets, another point I really don't understand, even when I'm in afk mode.

Jack -- I think the network settings limit downsteam only. I think the upstream bandwidth is pretty small in comparison to the downstream. What's "PL"?

Eggy -- I see what you mean. The sound bandwidth is lumped in with the "art" (textures) in the custom settings, so you can't limit the noise without also limiting the visible details.

Kelly -- Not all packets are the same size; some are small and terse while others are full and are elements of a set.

Andrew, PL = Packet Loss (sorry, i lazy)

I get less packetloss when I set to 100kps, and I can move around much better. I don't understand PL is affected when I download less. I receive data from other servers at much higher speeds with 0 packet loss. Usually it's only my upstream that causes my connection to start slowing down.

There's no such thing as 'unlimited downstream'. You have to remember that your connection is only as fast as it's 'weakest link'. Therefore if you're on an ISP with poor choices in peering or upstream provider (Verio, ATDN, etc) you will likely see decent performance to the "big" sites which peer everywhere, but to 'individual' sites such as SL, which are singly linked at Level3, your 'best' path to Level3 might not have as much bandwidth available as your closest hop does.

That said, I can't imagine SL's upstream usage would max out your upstream at any given point except for while uploading textures/sounds. In watching my bandwidth graphs, it's very apparent when i'm running SL from a downstream perspective, but there usptream traffic almost doesn't register. It's truly miniscule, even a 56k could handle it.

If you're turning up your bandwidth limit from 100k to 300k and seeing packet loss increase, you have one of the symptoms described at the beginning of this thread. Either the path between you and SL does not have 300k available at it's 'weakest' point, or you have a network failure condition (bad cable, bad switch, bad router, flaky wireless link, etc) which is causing you constant packetloss, which is just more visible under higher utilization.