I have a Internet Connection with ISDN Backup.
On the primary Link I have a GRE Tunnel to a Cisco 3662, which also terminates the ISDN BAckup in case of primary Link failure..
The customer have a IPSec Tunnel to 2 remote offices. The VPN to the Linux FW works fine.
On the VPN to a MS-ISA Server, some protocols do not pass (RDP, Sql).
This must be an MTU issue, because if its active the BAckup, the protocols will pass.
I can manage only the CPE 1721 and the 3662.
On all Interfaces of the CPE (1721) I have configured the following:
ip tcp adjust-mss 1300
So my question? What can be done at the ISA-Server to solve this problem?
Is there any possibility to resolve this problem without configuring the remiote Routers/Firewalls?
Regards and Thanks