Remote network problem

[KeithS]

Hi all, my first post here and I'm hoping someone may be able to give some advice.

We have set up two networks (each consisting of 2 PCs) at different office locations and we connect them using a VPN tunnel through the routers so that we have effectively one network. I have mapped the network drives as they were when all 4 computers were in the same office, and the database software that we use works but it is incredibly slow updating records now. What used to take a second to do, now takes around 40 seconds. All 4 machines have identical databases on them and each write duplicate data to the others so that each is constantly identical. We do not use a server.

If I ping one of the remote office PCs, the time is around 40ms. We are only writing around 2-3k of data each time to each machine so does anyone have an idea as to why it is suddenly so slow. Is it just due to internet latency, or is there something I can tweak on the PCs in order to get the records to update faster.

Each PC is using Win XP SP2 and the database application we use was written in DOS and runs in a command prompt window.

As a test, we ran a program that read 4 files (each 3k in size) from its own hard drive and then wrote them to a remote PC at the other location and it took 33 seconds, which seems terribly slow.

[Greg]

That's real slow. What are the pipes, DSL, Cable, T1?

[KeithS]

DSL both ends, 5mb down/700k up on the one and 2mb down/260k up on the other.

[Greg]

Yeah, that's not much bandwidth. Have you run a traceroute to see where the latency is if it's on the wire?

You also need to be sure your ISP is not resetting your connection because you look P2P.

[Zero Tolerance]

You need to provide more information before anyone can give you anything real to go on.

What type of VPN tunnel are you using? PPTP? IPSec? SSL? Each one will perform differently and ALL of them will run somewhat slower simply because of the encryption used in VPN tunneling. Its just some of the different protocols will run slower than another...with PPTP probably being the fastest.

You could try compression IF your equipment and protocol will support it. But it sounds to me just based on what you have said that the performance is about "PAR for the course".

I use VPN tunnels a lot and I never pass files across the VPN(or fractional T1 for that matter) simply because of the slowness of the link. Rather I put fileservers at each remote site and replicate them "realtime" with syncronization.

One thing I am currently getting into but havent tried across a slow link is iSCSI drives on a SAN. I am personally using OpenFiler but I am sure there are other opensource products out there that are similar. OF is opensource too.

Also since its a VPN tunnel I doubt that your ISP is resetting the connection because you look like your are doing P2P. The ISP should not be able to know what kind of data is flowing across the VPN tunnel, therefor should not confuse your traffic with P2P traffic.

[KeithS]

Thanks for the replies guys. The VPN tunnel is IPSec.

Here in the UK, upstream bandwidth of 260k is quite common, I could upgrade my account and get about 6mb down and 700k up, but that will result in worse pings for gaming for definite (as a fanatical online gamer I couldnt bear that!), so I am assuming that the ping will worsen across the board.

I think we may be better off using remote desktop when working from home, I've used it before and it is certainly much more straightforward than trying to remote network, plus it does everything we want. The reason I wanted to have two remote networks connected together rather than remote desktop is that it involves using less PCs. As we want to ultimately move to Canada and do our UK jobs from there, we have to find a system that works quickly. I expected the remote network setup to be a little slower than a LAN, but it was much slower in practice.

Someone on another forum suggested repairing the Winsocks on each PC, but I'm not convinced that is the problem.

[Greg]

I was hoping one of these guys would jump in. I don't do this type of networking.

[Zero Tolerance]

Well first off I would like to correct myself on my initial post. I typed PPTP being the faster VPN protocol....but I should have typed IPsec. Brainfart....but anyway. IPsec is the more fast protocol so you are good to go there.

So just for some "real world" comparison sake I tested a PPTP(slower) VPN tunnel and transferred a 12k file over about an 180ms in less than 2 seconds. My internet connection is cable and the transfer rate is 10325/2601 (see attachment for speakeasy.net test

I am getting almost 4 times the upload speed on my connection as you are. But you are also using IPsec which should be even faster as it processes the data transfer at a different level than PPTP....which is why its faster.

Using that logic you should in theory be able to say that the same size file (12k) should transfer on your link at around 6-8 seconds. 40 seconds now that I think about it is way more than you should expect.

Do the routers/modems have any firewalls built in? Running firewalls and real time antivirus on the PC's?

There is something that is slowing it down. Yes a VPN tunnel is much slower than that of even a 100mpbs LAN....but not quite as slow as your reports. So the most likely first place to look is at firewalls and real time virus scanners.

Let us know if you have any of that and want to pursue this discussion further.