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Verifying that your HMC DHCP private network is configured correctly

Learn how to verify that all of your HMC DHCP private networks are configured correctly.

If your HMC is configured as a DHCP server on a private network and is not communicating correctly with the managed system, or you have recently modified your network configuration (moved a managed system, replaced an HMC, or added a second HMC), use the following instructions to determine if your DHCP-managed private network is configured correctly.

Note: If your HMC is set up as a DHCP server on a private network, do not use the static IP commands mksysconn and rmsysconn to change HMC connection settings. These commands are intended for use on a public network only, where the HMC is not set up as DHCP server and managed servers use static IP addresses.

If a system administrator previously assigned an IP address to the system through a manually executed static IP command, Support must remove the manual connection and establish a DHCP connection between the HMC and the server. This section describes how to identify any manually assigned IP addresses so that an authorized service provider can remove them.

To identify a manually assigned IP address so that your HMC can communicate correctly with your managed systems, you must perform the following high-level tasks. The following are detailed step-by-step task descriptions.

Identify the configured HMC IP connection addresses and compare them to the list of IP addresses assigned by the DHCP server.
Identify the HMC IP connection addresses that have been correctly assigned through the DHCP server, for which no further action is required.
Identify any manually configured HMC IP connection addresses that DHCP did not assign and that need to be corrected by support.

To identify manually assigned IP addresses when the HMC is configured as a DHCP server, do the following

Create a list of all of the configured HMC IP connections. On the HMC command line, type the following command:
```
lssysconn -r all 
```
This command displays the following information for service processors and Bulk Power Cards (BPCs) on the network for which the HMC has configured IP connection:
```
element type, MTMS, IP address(es), connection state
```
Make a note of all IP addresses that are displayed. You will need these addresses later.
Display a list of the DHCP IP addresses that have been assigned. To do this, type the following HMC command:
```
lshmc -n -F clients 
```
The output of this command lists all IP addresses that have been assigned by the HMC’s DHCP server.
Make a note of all IP addresses that are listed in the output.
Compare the lssysconn and lshmc lists. If an IP address is displayed in the output for both the lshmc -n -F clients and lssysconn -r all commands, the IP address was assigned by the HMC DHCP server and the connection is being managed by the HMC DHCP server.
Remove from the list any address that is displayed in the output of the lshmc -n -F clients command but not displayed in the output of the lssysconn -r all command, and is not in the list of servers that use static IP addresses.
Note: If an IP address is displayed in the lshmc -n output and not in the lssysconn -r all output, that IP address was assigned by the HMC DHCP server. However, it is not a current connection on the HMC. The DHCP server keeps a history of all IP address assignments in the event that the connection is re-established. The DHCP server might also have assigned an IP address if an unknown device on the private network requested a DHCP IP address from the HMC.
If the HMC is managing servers on both a private and a public network, any connections to the service processor on the public network (not in the private network address range) must also be identified and removed from this list. If there are no IP adresses remaining in the list that contains the lssyconn -r all output, the HMC DHCP server has assigned all of the system IP addresses, and the network configuration is working correctly.
If there are any IP addresses not removed from the list taken from the lssysconn -r all command, this address was not assigned by the HMC’s DHCP server. These IP address assignments must be corrected, so that they can be automatically reassigned by the HMC DHCP server. Contact an authorized service provider and request that someone correct the manually assigned IP addresses that you have identified.

If you have followed this procedure and not all of your connections appear to be active, call an authorized service provider for additional support.

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Last updated: Sun, December 17, 2017