vpn links advice required

[projector1]

hi
i do a little bit of work for a local school (need the cash thus 12 hour shiifts daily mon-fri)
they have three sites. at the main site they have a 2003 AD server and a sims server.
What they want is to be able to allow office staff at the two remote sites to access sims.net (there is only two office staff at each site, so i guess it will be very light useage of sims.)
They would also like to have sophos rolled out to the pcs at both sites. (all pc's are xp pro expect 7 that are xp home)

They have sonicwall TZ170 at the two remote sites. They have a a pro model at the main site.

I have tried a few tests. we bought a client pc from the main site and tested it at the remote sites. When we try and log onto the domain, the machine responds with the message could not contact the domain controller, we were able to remote desktop the server though.
I also tried browsing to the folder that contains the sophos installtion files.
I can navigate to this within a few seconds. However when i double click the setup.exe file the window within seconds stops responding. I try these tests when there is hardly any network traffic aswell

I keep think that if the vpn link cannot handle a sophos install what will it be like if we try and install sims.net!

Any advice would be appreciated.

thanks

[Geoff]

Sounds like the netbios ports for windows networking are firewalled? Check ports 135-139 and 445 are open.

[tom_newton]

IME some of the windows networking stuff does not like VPN. Remember VPNs only handle TCP/IP traffic, so layer2 stuff like WINS is usually lost.

I believe our VPN kit proxys WINS, which might help, although it may well not be your problem! If you can, I suggest getting hold of WireShark (nee Ethereal) and seeing where the conversations "stop".

Customer of ours at a large UK college dropped TZ170s as they couldn't take the load - may be worth doing your tests at unloaded times of the day. Or night

[projector1]

tom many thanks for your advice.
each site has a 2mb connection if QOS was enabled on all 3 devices would that guarantees 1.5MB for ALL VPN traffic, is that possible in vpn systems?
we have been told that if the links were busy with internet traffic, the vpn connections are still guaranteed 75% of the line.
Your advice would be most welcome