Update adds support for the slow timer in LACP in Windows Server 2012 R2

Ισχύει για: Windows Server 2012 R2 DatacenterWindows Server 2012 R2 StandardWindows Server 2012 R2 Essentials

About this update

This article describes a hotfix that adds support for the slow timer in Link Aggregation Control Protocol (LACP) in Windows Server 2012 R2. Before you install this hotfix, check out the Prerequisites section. Additional steps are required to enable this hotfix after the installation.

Note The fast timer is already supported in Windows Server 2012 R2.

Hotfix information

Important If you install a language pack after you install this hotfix, you must reinstall this hotfix. Therefore, we recommend that you install any language packs that you have to have before you install this hotfix. For more information, see Add language packs to Windows.

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that's described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there's a "Hotfix Download Available" section at the top of this Knowledge Base article. If this section doesn't appear, submit a request to Microsoft Customer Service and Support to get 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 don't qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, go to the following Microsoft website: Note The "Hotfix Download Available" form displays the languages for which the hotfix is available. If you don't see your language, it's because a hotfix isn't available for that language.


To apply this hotfix, install update 2919355 on Windows Server 2012 R2. 

Registry information

To enable slow time-out, follow these steps:

Important Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restorationin case problems occur.
  1. In Registry Editor, locate and then select the following registry subkey:
  2. Press and hold (or right-click) <GUID>, select New, and then select DWORD (32-bit) Value.
  3. Name the new registry entry as LacpTimeout.
  4. Double-click the LacpTimeout registry entry.
  5. In the Edit DWORD Value dialog box, enter 0 in the Value data field, and then select OK.
  6. Exit Registry Editor.
  • When you set the LacpTimeoutregistry entry to a value of 0, the time-out value will be set to 90 seconds.
  • When you set the LacpTimeoutregistry entry to a value of 1, the time-out value will be set to 3 seconds.
  • After you set the registry key, you have to restart the NIC Teaming (LBFO) service by using the following commands. This causes a brief network disruption.
    sc stop mslbfoprovider
    sc start mslbfoprovider

Restart requirement

You may have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix doesn't replace a previously released hotfix.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


See the terminology that Microsoft uses to describe software updates.

File Information

The English (United States) version of this software update installs files that have the attributes that are listed in the following tables. The dates and times for these files are listed in Coordinated Universal Time (UTC). Be aware that dates and times for these files on your local computer are displayed in your local time and with your current daylight saving time bias. The dates and times may also change when you run certain operations on the files.