An alarm reports a loss of uplink redundancy on a vSphere standard or a distributed switch for a host.
Problem
No redundant physical NICs for a host are connected to a particular standard or a distributed switch, and the following alarm appears:
Host name or IP Network uplink redundancy lost
Cause
Only one physical NIC on the host is connected to a certain standard or a distributed switch. The redundant physical NICs are either down or are not assigned to the switch.
For example, assume that a host in your environment has physical NICs vmnic0 and vmnic1 connected to vSwitch0, and the physical NIC vmnic1 goes offline, leaving only vmnic0 connected to vSwitch0. As a result, the uplink redundancy for vSwitch0 is lost on the host.
Solution
Check which switch has lost uplink redundancy on the host. Connect at least one more physical NIC on the host to this switch and reset the alarm to green. You can use the vSphere Client or the ESXi Shell.
If a physical NIC is down, try to bring it back up by using the ESXi Shell on the host.
For information about using the networking commands in the ESXi Shell, see ESXCLI Reference. For information about configuring networking on a host in the vSphere Client, see vSphere Networking.
An alarm reports a loss of uplink redundancy on a vSphere standard or a distributed switch for a host.
Problem
No redundant physical NICs for a host are connected to a particular standard or a distributed switch, and the following alarm appears:
Host name or IP Network uplink redundancy lost
Cause
Only one physical NIC on the host is connected to a certain standard or a distributed switch. The redundant physical NICs are either down or are not assigned to the switch.
For example, assume that a host in your environment has physical NICs vmnic0 and vmnic1 connected to vSwitch0, and the physical NIC vmnic1 goes offline, leaving only vmnic0 connected to vSwitch0. As a result, the uplink redundancy for vSwitch0 is lost on the host.
Solution
Check which switch has lost uplink redundancy on the host. Connect at least one more physical NIC on the host to this switch and reset the alarm to green. You can use the vSphere Web Client or the ESXi Shell.
If a physical NIC is down, try to bring it back up by using the ESXi Shell on the host.
For information about using the networking commands in the ESXi Shell, see vSphere Command-Line Interface Reference. For information about configuring networking on a host in the vSphere Web Client, see vSphere Networking.
The error of network uplink redundancy lost is a very common issue with VMware ESXi hosts. It occurs when the secondary network interface is not connected or in a degraded state to the ESXi host. An alarm reports a loss of uplink redundancy on a vSphere standard or a distributed switch for a host.
At this point, the Host is connected with the primary NIC and there is no impact but if the primary adapter fails then there would be an outage as there is no network adapter to carry out the network traffic. Your host becomes isolated.
For example, assume that a host in your environment has physical NICs vmnic0 and vmnic1 connected to vSwitch0 on host esx01, and the physical NIC vmnic1 goes offline or down, leaving only vmnic0 connected to vSwitch0. As a result, the uplink redundancy for vSwitch0 is lost on the host esx01.
Possible Solution For Network Uplink Redundancy Lost
First, you need to check that which vSwitch has lost the uplink redundancy on the host. You need to connect at least one more physical NIC on the host to this vSwitch and acknowledge the alarm to green. This issue might be lost for a few seconds and could be intermittent network loss on the physical switch. In this case, you need to check and verify with your network support team.
If a physical NIC is down, Request to your Data Center Operation team to check physically to the physical NIC and connect the NIC properly.
You also can analyze the events or tasks for the Host which is complaining about this, and look into the Tasks & Events tab.
To check the connected NICs details using esxcli use below commands:
esxcli network nic listThe above command will provide you a list of network adapter with their status as up or down and duplex speed.
If you want to check the network errors on any particular physical network adapter(vmnic1 in this case), use below commands:
ethtool -S vmnic1 | grep -i errorThe ethtool is the best tool to check the physical network adapter information.
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ESXi : Lost uplink redundancy on virtual switch «vSwitch0». Physical NIC vmnic0 is down
We had an issue suddenly getting an alert : Lost uplink redundancy on virtual switch «vSwitch0″. Physical NIC vmnic0 is down. Affected portgroups:»vMotion», «Management Network».
So as a troubleshooting
Select the ESXi host effected Click on Configuration, Select Networking, Click on vSwitch0 Properties,Click on Network adapters Select on vmnic0, Click on remove, Click on Close
Again Select Networking, Click on vSwitch0 Properties,Click on Network adapters, Click on Add, Select the vmnic0, Click on Next, Click on Next, Click on Finish
Now Click on Ports tab of vSwitch Properties, Select on vMotion, Click on Edit, Click on NIC Teaming, Select on vmnic1, Click on Moveup button to Active Adapters, Select on vmnic0, Click on Move Down to Standby Adapters, Click on OK
Now Click on Ports tab of vSwitch Properties, Select on Management Network, Click on Edit, Click on NIC Teaming, Select on vmnic1, Click on Moveup button to Active Adapters, Select on vmnic0, Click on Move Down to Standby Adapters, Click on OK
Once you have done with the above steps now the you will not have the above error.
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NytroZ
asked on 7/2/2015
I receive a network redundancy lost error on a ESXi 5.5 host even though there is no sign of a connection error. The cable is connected and the switch port shows it is online. There is a vSwitch configured to connect to a SAN. There are 2 NIC’s configured and both of them show up as online in the vCenter. If I disconnect one of the NIC’s from that vSwitch I get a «network connectivity lost» error.
VMware
Last Comment
Andrew Hancock (VMware vExpert PRO / EE Fellow/British Beekeeper)
8/22/2022 — Mon
Andrew Hancock (VMware vExpert PRO / EE Fellow/British Beekeeper)
7/2/2015
Completely normal, you must have had a moment, where connection was down.
I think I may have described the issue poorly. I have an error that is persistant to one of my hosts. Is says «network uplink redundancy lost». Both nic’s to the SAN are connected. I also see partial/no redundancy in my storage view which leads me to believe that it detects one of the connections to the SAN as failed. I only disconnected the cable from the NIC to see if I would receive a different error.
Andrew Hancock (VMware vExpert PRO / EE Fellow/British Beekeeper)
7/2/2015
Have you cleared the error message, does it still appear as an alert ?
Have you checked both nics, and checked they are up and not down.
I checked both nic’s and they are both up. disconnecting either nic gives me a network connectivity lost error. I recently did updates on the host server and was wondering if maybe I need to update the drivers on the nic now. The error did not show up right after the ESX updates but more like a few days.
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Clearing the error got rid of it. Is it really that easy?
Andrew Hancock (VMware vExpert PRO / EE Fellow/British Beekeeper)
7/2/2015
Yes, the Alarms latch on, until you clear them.
So you’ve had a «spike» a nic has gone down, and the alarm is on. — until you clear or Acknowledge.