You receive a "Request timed out" error message when you use the Ping.exe command-line utility to verify network connectivity between Windows Server 2003-based NLB servers

Consider the following scenario. You have multiple Microsoft Windows Server 2003-based Network Load Balancing (NLB) servers that have physical IP addresses in a cluster environment. You successfully use the Ping.exe command-line utility on one of the NLB servers to verify network connectivity with another NLB server. You perform this action by pinging the physical IP address of the second NLB server. Next, you disconnect and then reconnect the network cable on the first NLB server. Then, you use the Ping.exe command-line utility again to verify network connectivity with the remote NLB server. However, when you use the Ping.exe command-line utility this time, you receive the following error message:Note This problem occurs only with certain specified cluster address and physical IP address combinations. For example, you experience this issue when the following conditions are true:

• You try to ping an NLB server that has a cluster IP address of 172.23.9.129 and a physical IP address of 172.23.9.137.
• The NLB server from which you perform this ping operation has the same cluster IP address (172.23.9.129).

This problem occurs because the order of the IP addresses that are stored in the ARPInterface structure is changed after you reconnect the network cable on the NLB server. Specifically, the first host sends an Address Resolution Protocol (ARP) request to resolve the second host's IP address. Therefore, ARP code searches the linked list in the ARPInterface structure for an address in which the network part of the address matches the network to which you want to send the ARP request. However, because the order of the IP addresses has changed, the ARP code finds the cluster address and then uses this as the source IP address.

Service pack information

To resolve this problem, obtain the latest service pack for Windows Server 2003. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

This hotfix does not require any prerequisites.

Restart Requirement

You must 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 item in Control Panel.

Windows Server 2003, x86-based versions

Windows Server 2003, Itanium-based versions

Windows Server 2003, x64-based versions

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
This problem was first corrected in Windows Server 2003 Service Pack 2.

Network connectivity between clients and servers may not work after you install the hotfix that is described in the "Resolution" section. This network connectivity issue is similar to an issue that you may experience after you install the MS05-019 security update. For more information about the network connectivity issue that is associated with the MS05-019 update, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the standard terminology that is used to describe Microsoft software updates, click the following article number to view the article in the Microsoft Knowledge Base:

Steps to reproduce the problem

1. Select two Windows Server 2003-based NLB servers. The configuration settings for these servers may be similar to the following :
   NLB 1 :
   Cluster IP address : 172.23.9.129
   Subnet Mask : 255.255.255.224
   Cluster Operation Mode : Multicast, Disable IGMP
   Host Dedicated IP address : 172.23.9.137
   NLB 2 :
   Cluster IP address : 172.23.9.129
   Subnet Mask : 255.255.255.224
   Cluster Operation Mode : Multicast, Disable IGMP Host
   Dedicated IP address : 172.23.9.136
2. Log on to NLB 2, and then open a command prompt.
3. At the command prompt, type ping -t 172.23.9.137, and then press ENTER.
4. Remove the network cable from NLB 2.
5. At the command prompt, try to run the ping command again. You receive a "Destination host unreachable" error message.
6. At the command prompt, type arp -a, and then press ENTER to verify that the ARP table is clear.
7. Reconnect the network cable on NLB 2.
8. At the command prompt, type ping -t 172.23.9.137, and then press ENTER. You receive a "Request timed out" error message, even after network connectivity is restored.