ISA Server 2004 may stop responding when IP addresses from multiple subnets are bound to the same adaptor (898553)

SYMPTOMS

Consider the following scenario. In Microsoft Internet Security and Acceleration (ISA) Server 2004, you configure an adaptor that has two IP addresses from two different subnets. Then, you enable an application filter, such as the remote procedure call (RPC) filter. In this scenario, ISA Server 2004 may stop responding (hang). You may also experience the following symptoms:

Many packets are backlogged in ISA Server 2004.
CPU utilization increases on the ISA Server 2004 computer.
The Active Directory Application Mode (ADAM) server cannot open new RPC connections to this ISA Server 2004 computer.
The log viewer displays various reasons for why the ADAM server cannot open these RPC connections. These reasons include the following types of errors:
- Errors that pertain to backlogged packets
- The "FWX_E_TOO_BUSY" error

CAUSE

The issue occurs when you use two IP addresses from different subnets to configure an adaptor. In this scenario, the ISA Server 2004 interpretation of the routing table differs from the interpretation that is made by the operating system. Specifically, ISA Server 2004 calculates a local IP address that is different from the real address that is used by the operating system. Therefore, ISA Server 2004 uses the wrong source IP address to create a state for the traffic. And when the traffic is inspected, no matching state is found. Therefore, ISA Server 2004 creates an additional mismatched state and then tries to resend the traffic. This process is repeated infinitely.

RESOLUTION

Service pack information

To resolve this problem, obtain the latest service pack for Internet Security and Acceleration Server 2004. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

891024 How to obtain the latest ISA Server 2004 service pack

Hotfix information

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft Internet Security and Acceleration (ISA) Server 2004 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

If you are running ISA Server 2004, Standard Edition, you must install ISA Server 2004 Service Pack 1. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

891024 How to obtain the latest ISA Server 2004 service pack

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
ISA Server 2004 Standard Edition

   Date         Time   Version            Size    File name
   ----------------------------------------------------------
   31-May-2005  00:48  4.0.2163.260      364,304  Msphlpr.dll

ISA Server 2004 Enterprise Edition

   Date         Time   Version            Size    File name
   ----------------------------------------------------------
   27-Apr-2005  13:34  4.0.3440.260      394,008  Msphlpr.dll