An IPSec site-to-site connection to a third-party remote IPSec tunnel endpoint fails and an incorrect key lifetime value is used for the Internet Protocol Security (IPsec) Main Mode in Microsoft Forefront Threat Management Gateway (TMG) 2010.
TMG uses a hardcoded value for IPsec Main Mode lifetime setting of an IPSec Security Association. This problem occurs because TMG does not correctly handle the value that you enter in the Authenticate and generate a new key every xxx seconds setting for Main Mode (Phase I).
Although you can configure a custom value for the Authenticate and generate a new key every xxx seconds setting, TMG ignores this setting and uses a value of 7200 instead. Therefore, IPSec tunnel mode connections may fail.
To resolve this problem, install Rollup 5 for Forefront Threat Management Gateway 2010 Service Pack 2.
To work around this problem, change the configuration of the remote tunnel endpoint to match the value of 7200 seconds for Main Mode on the TMG server.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
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