Network Troubleshooting 101 – vSphere VM Guest (Updated)
General Information (VMware information): (Updated)
What is Beacon Probing?
Well, if you don’t know I would give the following Kb a read.
You can find that here:
Let’s hope I can do this some “Justice”
A few weeks ago I ran into an issue where VM NICS would just randomly go down. The only way I could get them back online was to perform a vMotion of the VM to another host and resetting the port connection on the dvSwitch seemed to fix the issue. So essentially I wanted to highlight some basic troubleshooting steps and things you can do to help you better pin point where the issue may be occurring.
- From the Guest VM having the issue attempt to ping any other VM on the same host, switch, and portgroup. This will allow to pin point the issue to see if it is related to the physical or virtual networking.
- Enabling Beacon Probing can help detect upstream failures. (Be sure to read up on it) Enabling beacon probing will increase bandwidth utilization and CPU cycles on an ESXi host so simply consider the tradeoffs.
Why I need to enable it?
VMware recommends to introduce this change for either permanent or temporary use. Beacon probing as stated above can help or allow us to detect other failures which may occur upstream. When the failure occurs on the VM this will help you isolate the issue as being related to the VMware Virtual networking or the Physical switching (So can troubleshooting). If the failure happens on the VM and the Virtual Switch uplinks trigger an alert this will help you to pin point the issue.
Enabling Beacon Probing for Distributed Virtual Switch for a vCenter:
- Before enabling Beacon Probing I will engage James Hendrock to get Bandwidth utilization before and after enabling Beacon probing.
- Log on into the vSphere Client and connect to any vCenter you want to change it on
- Browse to Home > Inventory > Networking
- Expand the following objects in the tree to the left: (see figure)
Right Click a Port Group under the dvSwitch switch > Edit settings…
Highlight under policies the Teaming and Failover: (see figure)
- Select Network Failover Detection Dropdown (should currently say Link Status only) > Select Beacon Probing (see figure)
- Click Ok
- Repeat steps 4-7 for all other Port Groups on dvMgmt dvSwitch.
- Beacon probing is best used with a 3-pNIC configuration with even a N+2 Switching design being highly recommended
- Beacon probing configured with 2-pNICs means that whether or not you use it in a N+1 configuration it will detect a downstream failure but it has no way of knowing which uplink is bad.
- In a 2-pnic configuration if one fails it will trigger a redundancy lost message but at the same time just shotgun traffic down both pNICs to ensure communication is sent.
- If you are going to use Beacon Probing you must also consider the network design.
http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1005577&sliceId=1&docTypeID=DT_KB_1_1&dialogID=273348945&stateId=0 0 273356736
http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1012819&sliceId=1&docTypeID=DT_KB_1_1&dialogID=273348945&stateId=0 0 273356736
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