Problem with lots of clients

[Ficuzo]

Hi,

I am trying to run conferece where I have 1 server and 20-40 clients. The problem is that when there is more than 5 connections approx., the view starts to lag. I have made some investigation and discovered next:
1. I was not using mirror driver from begining - so the whole server PC was lagging when had lots of clients. I have installed mirror driver and that problem solved - server PC lags no more. Bad thing is that with big quantity of clients UltraVNC server software seems like lagging still - I have like ~20 seconds waiting time till the properties screen opens up.
2. Seems like problem could be in traffic limitation - I am trying this setup in LAN and get 2Mbps traffic with one client and only 4Mbps max not depending on how much clients - 5 or 30 I have At the same time FPS dropping with a every new connection. Switching from 1.0.1 server to 1.0.2 server helped a little with 1 connection I get better results, but it does not help with many clients

The biggest problem is that it sometimes stalls for a 5-30seconds even. So - is there any chances of getting out of this situation? Maybe I need some extra configuration or similar?

Looking forward to any sollution...

[bevtech]

What kind of internet connection are you using?? You can try to connect via viewer by choosing slow. May give you a few more but 30 may not be possible..

[Ficuzo]

I am using this setup almost in LAN situation - clients are located in other cities, but our core connection between capital (where the server is) and these cities is at least 10Mbps to each. Of course all this is limited to 100Mbps link to server.

While searching for a problem tried to change ethernet settings on server connection. Made 100FDX from AutoNegiotiate on both server and switch - does not help

[rolf]

We have more or less the same problem, but we only want to connect up to 10 viewers. And these have at least 100 Mbit connections. But we still have performance problems too. When all of the screen changes the time delays are 15 to 20 seconds.

We have done several tests, to find out what may help to speed up the connection a little.

We found out that the slowest connection set the speed for all connections (with smal deviantions). So if you have someone connected with a slow connection (i.e. modem) the others will more or less fall down to his framerate/bandwith.
The overall bandwith is of course influenced by the connection you have on your server. If you have 40 clients you could only have a maximum of 2,5MBit/s for each client. In fact it will be much lesser than that. When you show a video over VNC it will demand more than 60MBit/s when you want to see it more or less fluently.

The first thing you can do is to select a lesser color depth. If you select 16 MBit instead of 32 only half of the bandwith is needed. If you can go down to 256 colors or less it will be even better.

An other solution ist to use one or more VNC-Reflectors. In this way you won't have so much traffic on one connection. And the Reflector is design to handle many connections. But he does this by automaticly switching down to less colors (down to 4 colors in the worst case). If it is important to you that the VNC-screen still looks good, the reflector will not be such a good choice.

We tried to build some chains with VNC-viewers and servers, where you have your initial server which connects to lets say 4 viewers. There is again a VNC-Server running on the viewer and we connect 4 additional viewers with these in the second line so that we have 20 viewers in this way. A problem here is that the 16 viewers are again slower than the first 4, which already have a delay.

Next we want to try the "-multi" option that we found recently. We hope to overcome the problem that the slowest connection sets the speed this way, but we are not sure.

As I was told, the problem with the slowest connection has to do with buffers for sending and receiving. Once the buffer is full all have to wait until some stuff can be delete from the buffer again. Things would probably improve if the buffers would be bigger and when there are different buffers for the connections.

[redge]

instead of vnc-reflector, try ultravnc repeater as proxy (mode I)
http://sc.uvnc.com/index.php?section=27
[topic=3389][/topic]

Not tested my self with your network config.

[rolf]

Does the Repeater really offer a better performance? When we tested it a while ago, it seamed to us that the repeater only does some routing, and we did not get a better performance.

The aim of the Repeater in Mode I seems to me to be able to access several Severs with a private IP.
The aim of the Refector is to make one server able to be accessed by more clients.

But when you say that the Repeater does the same as the Reflector and more we'll give it another try.