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Jan Mulders wrote: > Just a general observation here (not related to openvpn/remote desktop > as such), but when downloading files from a UK server, if the server is > locally loaded (eg, 1-2 local machines pulling 20-30Mbps from it), then > an international machine's connection drops from 10mbps to under 1mbps - > despite the main server having plenty of spare capacity in both > throughput and bandwidth. > > This suggests that udp/tcp performance degrades significantly over high > latencies - maybe it's a packet jitter (packets arriving early/late due > to routers having to squeeze the packets into gaps in other traffic) > causing the connection to throttle? as OpenVPN in UDP mode basically > lets the protocol that's being tunneled through it handle packet > sequencing etc, it means that your tcp connection for remote desktop is > directly affected. > > Anyone else on the list, feel free to correct/add to this. Yes, so that would suggest a more general problem. One fellow here pointed out that routers are often "smart" enough to not drop TCP packets when things start to get busy, since TCP is a connection-based protocol. The router knows that if it drops the packet it will just have to send it again, so it's better just to make sure it gets through. UDP is connectionless however, so the router will assume that it can drop UDP packets with few repercussions. One further note to my original post; we tried running the client in TCP mode as per #5 below, but as the manual predicted, things only got worse. Thanks for the response Jan, Matt. > Forgive my ramblings, just trying to think the problem through :) > > Jan > > On 02/02/07, * Matt Wilks* <matt@xxxxxxxxxxxxxxxxxxxxxxx > <mailto:matt@xxxxxxxxxxxxxxxxxxxxxxx>> wrote: > > Hi all, > > We run a small OpenVPN server in UDP mode here that has anywhere from > 20-40 clients connected at any given time. One of our users has > recently been complaining of significant lag (which manifests itself in > keystrokes that take 5-10 seconds to appear on screen) when using Remote > Desktop over an OpenVPN connection. Some more details: > > 0. The OpenVPN server is not taxed in the least; CPU usage hovers around > 1% and bandwidth averages 500Kb/sec > 1. The user only experiences this lag when the network is congested: > usually around 10pm at night (he is coming into our network over a > Sympatico connection). > 2. When using the built-in Windows XP VPN client to connect to his > desktop via Remote Desktop, the lag all but disappears (this is on > the same congested network, around the same time of night). > 3. There is a packet shaper between the user's home and our network, > but > this has been ruled out as the culprit by turning it off for OpenVPN > traffic. > 4. I saw a posting a while back on the list where James suggested > fiddling with the MTU datagram sizes, but that doesn't seem to > be the > problem here since the user is not experiencing any lag during > non-peak usage times of the day. > 5. We are going to test the user on a server running OpenVPN in TCP > mode, but I'm not too hopeful about that since the manual indicates > that this almost always gives worse performance overall. > > I realize this may not be an OpenVPN issue at all, but I thought I would > write the list and see if anyone else has experienced similar problems. > > Thanks in advance, > Matt > > > ------------------------------------------------------------------------- > security? > Get stuff done quickly with pre-integrated technology to make your > job easier. > Geronimo > _______________________________________________ > Openvpn-users mailing list > Openvpn-users@xxxxxxxxxxxxxxxxxxxxx > <mailto:Openvpn-users@xxxxxxxxxxxxxxxxxxxxx> > https://lists.sourceforge.net/lists/listinfo/openvpn-users > > > > ------------------------------------------------------------------------ > > ------------------------------------------------------------------------- > Get stuff done quickly with pre-integrated technology to make your job easier. > > > ------------------------------------------------------------------------ > > _______________________________________________ > Openvpn-users mailing list > Openvpn-users@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/openvpn-users ______________________ OpenVPN mailing lists https://lists.sourceforge.net/lists/listinfo/openvpn-users |