"Reason Bridge is not allowed to run inside VM" in VMSwitch

Jim Gandy 121 Reputation points
2021-05-21T20:39:45.303+00:00

All VMs on a Hyper-V host have no access thru VMSwitch and are getting this message in the VMSwitch trace

Line 943: [0]0000.0000::2021-05-21 12:14:16.317526700 [Microsoft-Windows-Hyper-V-VmSwitch]NBL destined to Nic 614099AE-255F-4ADD-8273-8D03A7BB15A3--E4A7F069-7F6A-4208-837C-4CB24E545CA7 (Friendly Name: Network Adapter) was dropped in switch 895740F7-F2AD-41EA-8A83-5132689DB3F2 (Friendly Name: S2DSwitch), Reason Bridge is not allowed to run inside VM

Anyone know what this means?

Windows for business | Windows Client for IT Pros | Storage high availability | Virtualization and Hyper-V
Windows for business | Windows Server | Storage high availability | Clustering and high availability
{count} votes

2 answers

Sort by: Most helpful
  1. JiayaoZhu 3,926 Reputation points
    2021-05-24T06:42:24.5+00:00

    Hi,

    Thanks for posting on our forum!

    Based on your descriptions, I may need more information. The error message is related to a NBL issue and I guess you configured S2D and NLB and maybe NIC teaming. So, I need you to give me details about your network configuration environment.

    Secondly, after my research, I found a case which was similar with yours. You can follow the guidance in the investigation on that case, to see if your issue can be solved:

    Hyper-V drop arp reply package?
    https://hyper528.rssing.com/chan-14866939/all_p335.html

    (Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.)

    If you are still stuck in this issue. I would suggest you contact Microsoft Customer Support and Services where more in-depth investigation can be done so that you would get a more satisfying explanation and solution to this issue. This issue, in my experience, may need to capture traffic packets, which is beyond our Q&A scope. You may find phone number for your region accordingly from the link below.
    Global Customer Service phone numbers:

    https://support.microsoft.com/en-us/help/13948/global-customer-service-phone-numbers

    Thanks for your understanding and support!

    BR,
    Joan

    --------------------------------------------------------------------------------------------------------------------

    If the Answer is helpful, please click "Accept Answer" and upvote it.

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

    0 comments No comments

  2. Jim Gandy 121 Reputation points
    2021-09-16T15:34:51.69+00:00

    We found the solution. There was a loop in the upstream network.

    0 comments No comments

Your answer

Answers can be marked as Accepted Answers by the question author, which helps users to know the answer solved the author's problem.