HCX unable to pair sites

Resolving The Problem

What';s Happening

HCX Enterprise Manager has been installed and registered successfully, however, you are unable to create a site pair with the HCX Cloud Manager.

How to resolve

Use the following steps to troubleshoot when the site paring fails with a "SocketException" error:

1. To prove you have a connection from the HCX Enterprise Manager to the HCX Cloud Manager, SSH onto the HCX Enterprise Manager.
   You might need to enable SSH on the appliance; if so refer to the VMware article Enabling SSH on the HCX Manager.
   
   
2. Log into the HCX Enterprise Manager by referring to the VMware article Logging into the VMware HCX Manager CLI.
   
   
3. Issue the command
   
   curl -k http://<HCX Cloud Manager IP> -v
   
   You should see a successful return of the header page from the HCX Cloud Manager. This means that you have connectivity on TCP port 443 to the HCX Cloud Manager.
   
   
4. Issue the command
   
   ping -M do -s 1472 <HCX Cloud Manager IP>
   
   For standard MTU of 1500 bytes, the maximum data size is 1472 bytes (MTU minus 20 bytes IP header and 8 bytes for the ICMP header). If a standard MTU size is not allowed, the following error message appears: "Message too long." If you see this error, it means the sites are not allowed to pair because the MTU is set too low and packets are being dropped.
   
   
5. Check all network settings on the devices in the path between HCX Enterprise Manager and HCX Cloud Manager, and change settings as appropriate. If possible, use the largest MTU size allowed by your network. The IBM Cloud Private network is jumbo frames enabled and allows MTU sizes up to 9000 bytes. The IBM Cloud Public network is configured with a MTU size of 1500 bytes.
   
   
6. Confirm that fragmentation is not occurring with the ping command used in Step 4 above. If no fragmentation, then initiate the site paring again.

Note, with fragmentation occurring you will see the following additional symptoms, which seems to suggest that the network is OK:

• A standard ping between the HCX Enterprise Manager and the HCX Cloud Manager is successful
• Traceroute is successful.
• Using telnet to port 443 is successful.
• Using a web browser on the source site and connecting to <HCX Cloud Manager IP>, shows the certificate page, but you are unable to proceed with the connection.

Refer to the VMware article HCX Troubleshooting for additional guidance on aspects of troubleshooting HCX.