Setting up DHCP for IBM Fusion HCI

As a prerequisite to IBM Fusion HCI installation, update Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS) with the information that is detailed in the planning worksheet for your system.

Before you begin

Download the installation preparation worksheet and review the network preparation section. To download the worksheets, see IBM Fusion HCI Installation worksheets.

  • Ensure that you have the MAC addresses from your IBM Technical Seller with whom you engaged with. If you do not have your IBM Technical Seller contact information, see the planning worksheets for contact details.

    To download the worksheets, see IBM Fusion HCI Installation worksheets.

  • The sample files that are used in this section are based on standard DNS/DHCP services available on Red Hat® Enterprise Linux 8.

About this task

Important: If you are using static IP, then you do not have to do a DHCP setup.
You can access IBM Fusion OpenShift® Container Platform cluster nodes on your network. As such, each cluster node requires an IP address that is accessible on this network. During installation, each cluster node obtains its IP address from an external DHCP server based on the MAC address of the cluster node. As a prerequisite for IBM Fusion HCI installation, you must reserve few IP addresses for OpenShift:
Note: All these IPs must be in the same range.
  • One IP address for the OpenShift API server endpoint
    For example:
    • API in DNS lookup file.
      api		    IN	A	10.44.100.143
    • API in DNS reverse lookup file.
      143	IN	PTR	api.isf.mycompany.com.
  • One IP address for the wildcard ingress endpoint (to access your workloads)
    For example, ingress in DNS.
    ; Ingress LB (apps)
*.apps		IN	A	10.44.100.144
  • One IP address for each cluster node (control, compute, AFM, and GPU nodes)
  • One IP address for the bootstrap node (it is temporary and is only required during the OpenShift Container Platform installation)
    For example:
    • Bootstrap in DHCP.
      host bootstrap.isf.mycompany.com { option host-name "bootstrap.isf.mycompany.com"; hardware ethernet 00:16:3e:e0:31:65; fixed-address 10.44.100. 151; }
    • Bootstrap in DNS lookup.
      bootstrap   IN  A   10.44.100.151
    • Bootstrap in DNS reverse lookup.
      151	IN	PTR	bootstrap.isf.mycompany.com.
Note:
  • For each cluster node and the bootstrap node, you must add DHCP reservations to your DHCP configuration.
A single sample DHCP reservation record for a cluster node looks similar to the following example:
host control-1-ru2.isf.mycompany.com { option host-name "control-1-ru2.isf.mycompany.com"; hardware ethernet 04:3f:72:f7:2f:76; fixed-address 10.44.100.145;}

IBM provides the node's hostname (for example, control-1-rux) and hardware Ethernet (MAC) address and you cannot change them. The fixed-address that you provide is the IP address that gets assigned to the cluster node.

A fully functional DNS environment is a requirement for IBM Fusion HCI and OpenShift Enterprise to work correctly. Adding entries into the /etc/hosts file is not enough because that file is not copied into containers that are running on the platform. For more information about DHCP and DNS, see OpenShift documentation.

Mapping of rack unit with OpenShift host name in a single rack with 9155-C10, 9155-C14, 9155-G03 servers:

For rack that supports 9155-C00, 9155-C01, 9155-C04, 9155-C05, 9155-G02, 9155-G03, and 9155-F01 servers, see IBM Fusion HCI 2.8.x documentation for host name conventions.

For rack that supports 9155-C010, 9155-C014, G03, and Service node, use the following table as reference for host name conventions:
Rack unit Host name Node type
RU2 control-1-ru2.<domainname> Storage or compute-only
RU3 control-1-ru3.<domainname> Storage or compute-only
RU4 control-1-ru4.<domainname> Storage or compute-only
RU5 compute-1-ru5.<domainname> Storage or compute-only
RU6 compute-1-ru6.<domainname> Storage or compute-only
RU7 compute-1-ru7.<domainname> Storage or compute-only
RU23 servicenode-1.<domainname> Service node

After RU7 any type of nodes can be installed on the next available RU. The naming convention is based on the RU number in the format compute-1-ru<x>.<domainname>.

Mapping of rack unit with OpenShift host name for a high availability multi rack cluster:
Rack unit Host name Node type
  Rack 1 Rack 2 Rack 3  
RU2 control-1-ru2.<domainname> control-2-ru2.<domainname> control-3-ru2.<domainname> Storage or compute-only
RU3 compute-1-ru3.<domainname> compute-2-ru3.<domainname> compute-3-ru3.<domainname> Storage or compute-only
RU4 compute-1-ru4.<domainname> compute-2-ru4.<domainname> compute-3-ru4.<domainname> Storage or compute-only
RU5 compute-1-ru5.<domainname> compute-2-ru5.<domainname> compute-3-ru5.<domainname> Storage or compute-only
RU6 compute-1-ru6.<domainname> compute-2-ru6.<domainname> compute-3-ru6.<domainname> Storage or compute-only
RU7 compute-1-ru7.<domainname> compute-2-ru7.<domainname> compute-3-ru7.<domainname> Storage or compute-only
RU23 servicenode-1.<domainname> compute-2-ru23.<domainname> compute-3-ru23.<domainname> Compute-only and Service node in base rack

After RU7 any type of nodes can be installed on the next available RU. The naming convention is based on the RU number in the format compute-1-ru<x>.<domainname>. In a multi-rack setup, the service node can be added to any one of the racks.

Procedure

  1. Place your DHCP servers in the same VLAN as IBM Fusion HCI unless the DHCP relay agent is used.
  2. Verify whether the DNS server is accessible from outside the IBM Fusion HCI by using either the ping <server-ipaddress> or the nslookup <server-ipaddress> command.
    Note: The DNS server can be anywhere but must be reachable, that is, the installation and cluster must have access to your network.
  3. After the verification is complete, set up DHCP reservation for each node. For more information about setting up the DHCP, see Setting up DHCP.
  4. Set up the DNS reservation for each node. For more information about setting up the DNS, see Setting up DNS.
    Here, ensure that you use the same domain-name-servers value and option host name that you used in DHCP configuration as they are interconnected. Make sure that the fixed addresses that you configure here is same in DHCP as well.
    Note: Ensure that the subdomain consists of lowercase alphanumeric characters, '-' or '.', and starts and ends with an alphanumeric character. For example, example.com. The regex used for validation is 'a-z0-9?(\.a-z0-9?)*')",