Dell CloudLink: svm status connection is showing both CloudLink nodes as Inaccessible

When running command svm status it shows the State as Connected.

svm status

However when running command svm status connection it's showing both CloudLink nodes as Inaccessible.

svm status connection

In the CloudLink webUI > AGENTS > Machines the status of the agents is showing Connected.

Try restarting the CloudLink agent to refresh the connection by restarting the svmd service:

systemctl restart svmd

If the CloudLink nodes are still showing as Inaccessible when running svm status connection, this could indicate that UDP port 1194 is getting blocked by a firewall. The CloudLink agents installed on the SDS nodes must be able to reach CloudLink over port 1194 for both TCP and UDP. If TCP port 1194 is blocked, this would be impactful and the SDS nodes would not be able to unlock their disks after a reboot. If UDP port 1194 is blocked, this is not impactful and the SDS nodes should be able to unlock their disks after a reboot.

​​Even if the firewall is blocking UDP port 1194 it still shows the connection succeeded when running command:

nc -zvu cloudlink.ip 1194

Netcat is not a reliable way to check UDP traffic. If the firewall is configured to reject the packets, you will not get a response. However if the firewall is configured to drop the packets it will still show the port as open.

We ran a tcpdump on the CloudLink appliance and did not see any UDP packets from the SDS nodes so it is likely UDP port 1194 is being blocked. The customer worked with their firewall team to open UDP port 1194. Source is SDS nodes, and the destination is CloudLink appliances. CloudLink Engineering must be engaged to gain access to the CloudLink console since it is locked down. 

/usr/sbin/tcpdump host sdsnode1.ip or sdsnode2.ip or sdsnode3.ip and port 1194 -i any

This is what we would expect to see if both TCP and UDP port 1194 are open.

Since the CloudLink console is locked down, you could instead run tcpdump on the SDS nodes. If UDP port 1194 is being blocked, we will only see UDP packets that say Out.

/usr/sbin/tcpdump host cloudlink1.ip or cloudlink2.ip and port 1194 -i any

If UDP port 1194 is open, we should see UDP packets that say In and Out.