PPTP VPN Routing Issues

[KevinBugg]

Hi,

We have a setup where users of one company (site A) access resources at another network (site B). They connect using the pptp vpn client and they authenticate on the domain using RAS.

Can we have simultaneous connections.e.g. can a user one Site A connect to Site B via pptp and another user at Site B connect to Site A at the same time?

At the moment, when this happens, routing appears to mess up and the users are unable to access resources.e.g. ping fails etc although the VPN claims to still be connected and the RAS server also claims the user is still connected.

I have been trying to diagnose this problem for weeks now and it appears to be the only logical thing i can think of

Thanks in advance

Kev

 

[gavm99]

Yes that is possible.

Ok lets start with the basics.

Are the two sites on different IP ranges?

Eg:
Site A is 192.168.1.x
Site B is 192.168.2.x


Gavin Moorhouse

http://www.lucidcomputersolutions.co.uk

Interested in my personal blog?

http://www.thelucidview.co.uk

 

[KevinBugg]

Yes they are. Site A is 192.168.x and Site B is 193.195.x. The connection from Site A authenticates and users can connect to the exchange server. Then all of a suddent at random times routing will fail and the connection through to exchange will fail. The vpn connection it self remains live and the RAS server also shows the connection is live but pings and tracert between the 2 end in request timed out. I am really baffled with this one!

 

[gavm99]

What happens if you just have one user connected on their own? Does all work ok?

Gavin Moorhouse

http://www.lucidcomputersolutions.co.uk

Interested in my personal blog?

http://www.thelucidview.co.uk

 

[KevinBugg]

Not all the time. I had 2 connections from Site A last night. One machine connected to the router and one connection connected behind the ISA firewall. Both ping a server at Site B 50,000 times. When i checked this morning niether had lost a packet.

Running it again during today, the problem is back. It maybe a coincindence but the request timed out problem always seems to happen when i am monitoring the machine. I am located at Site B so for me to get Site A pinging a machine at Site B i have to pptp connect as well so its a pptp connection both ways. I am wondering if that messes up RAS or something?

 

[gavm99]

Ok, I realise I am steering away from the problem here but wouldn't you be better off with a site to site VPN rather then individual ones?

Gavin Moorhouse

http://www.lucidcomputersolutions.co.uk

Interested in my personal blog?

http://www.thelucidview.co.uk

 

[KevinBugg]

As they are 2 seperate companies, they are wanting to keep them as seperate as possible.

Also, the vpn pptp connections are only used on a monthly basis when meetings are held at Site A and when i have to dial in to repair or run maintenance on a weekly basis.

 

[gavm99]

Ok, going back to the original problem - have you tried adding entries to your local routing table to help things along?


Gavin Moorhouse

http://www.lucidcomputersolutions.co.uk

Interested in my personal blog?

http://www.thelucidview.co.uk

 

[KevinBugg]

i haven't. i have left this to the ras server to sort out. any suggestions and guides?

 

[gavm99]

What I would do is simply connect from SiteB to SiteA and then do a route print to ensure you can see entries for the route over to SiteA.

From there also try a tracert to the server or gateway at SiteA and ensure this works ok.

As a final test do a quick ping on the device you did the tracert to.



Gavin Moorhouse

http://www.lucidcomputersolutions.co.uk

Interested in my personal blog?

http://www.thelucidview.co.uk