I have replaced a PIX with an ASA5510 running 7.2 code. The VPN to a 3000 series concentrator runs fine but the VPN to a PIX running 6.2 code only works if we issue a "clear crypto isakmp sa" on the PIX. It then runs fine until something interupts it (say the Internet connection drops for a few seconds). Then it never re-establshes until we again do a "clear crypto isakmp sa" on the PIX. Rebooting the ASA does not help. The connection from the ASA to the 3000 concentrator on the other hand comes back up fine after an interruption.
Any ideas ?