Article ID: 946715 - View products that this article applies to.
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Consider the following scenario:
This problem occurs because ISA Server 2006 incorrectly assumes that the GRE traffic is always encapsulating Point-to-Point Tunneling Protocol (PPTP) packets. Therefore, if the GRE packet does not contain a valid PPTP header, the traffic is blocked.
To resolve this problem, apply the hotfix that is mentioned in the following Microsoft Knowledge Base article:
(https://support.microsoft.com/kb/959357/ )Description of the ISA Server 2006 hotfix package: October 29, 2008
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about GRE, visit the following Internet Drafts Web site:
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
(https://support.microsoft.com/kb/824684/ )Description of the standard terminology that is used to describe Microsoft software updates
Article ID: 946715 - Last Review: January 16, 2015 - Revision: 2.0