Network configuration and requirements

IBM® Flex System Manager management software uses a management network to connect to managed resources in multiple Flex System Enterprise Chassis. An optional data network supports the discovery of operating systems on managed resources and provides connections for other management software functionality.

Management and data networks

There are two Ethernet network interfaces for the Flex System Manager Types 7955, 8731, and 8734 management node: Eth0 and Eth1. The Ethernet interface Eth0 is associated with the management network. Eth1 is associated with the data network. For more information about configuring the network for Flex System Enterprise Chassis, including network integration diagrams, see Network integration.

Note:

The management node console can be connected to the management network or the data network. To configure the management software to access a single network that is using a single IP subnet, configure only the Eth0 interface. To configure Eth0 and Eth1, you must configure them on different IP subnets.
To manage a chassis on the local subnet, make sure that the IP address that is assigned to Eth0 is on the same IPv4 subnet or IPv6 network as the IP address that is assigned to the CMM. To manage a chassis on another subnet, you must first discover the chassis manually. After the chassis is discovered, it appears in the chassis list on the Management Domain page.

When you start the management node for the first time, you must establish an initial network configuration so that the initial setup wizard is accessible from a web browser.

Important: DNS server configuration is required on the data network (Eth1) for the following management software functions:

Using VMControl to manage virtual machines and operating systems that are running on compute nodes
Updating the device drivers in the operating systems that are running on IBM Power Systems™ compute nodes

If the management software is managing one or more chassis in centralized user management mode, and you want to modify the IP address for the Eth0 interface, you must first unmanage the chassis that are centrally managed. After you modify the IP address, you can manage the chassis again. For more information, see Centralized user management.

For more information about initially configuring the network, see Initial setup. For more information about configuring network settings in the Setup wizard, see Setting up the IBM Flex System Manager management node.

Network requirements for the IBM Flex System Manager management node

To manage a chassis and all resources in a chassis, the IBM Flex System Manager management node and all other chassis resources must have routable IP addresses on the management network. Whether you use IPv4 or IPv6 addressing, all interfaces must have routable IPv4 or IPv6 addresses.

Important: If you use IPv4 and IPv6 for the management node Eth0 (management network interface), each managed chassis and chassis component must have an IPv4 address.

You can select an IPv6 Unique Local Address (ULA) IP address to ensure that the Eth0 port has a valid IP address. If the option was selected when the initial setup wizard was completed, the management node network port (Eth0) IPv6 address might have already been assigned.

Important: The management software virtual machine uses the mgmt0 interface to communicate with the host operating system. Do not change the mgmt0 interface.

Attention: IBM Flex System Manager uses the 10.3.x.x network for internal communications. The TCP standard states that the 10.x.x.x network is a private network that cannot be used for routed systems. If FSM is configured on this network, it is likely that FSM cannot communicate on the network. However, the Integrated Management Module (IMM2) of FSM on the same network can communicate without any issue.

Network requirements for managed resources

Be aware of the following network requirements for managed chassis, compute nodes, and network devices.

A network device or switch must have a static, DHCPv6, or stateless IP address assigned to it; a network device with a link-local address (LLA) cannot be managed by the management software.
Note: When Flex System is set up, the RHEV-H partition uses a specific IP address (10.3.0.1) that is hardcoded in the system. Therefore, when you manage resources in Flex System do not use the IP address 10.3.0.1 as it is reserved for the RHEV-H partition.
A compute node or storage node that is on the same subnet as the management node can use an LLA if the configuration is on a flat L2 network (with no routers). Routers will not forward packets with LLAs. If the configuration is on a routed network, the compute node must have a static, DHCPv6, or stateless IP address assigned to it.
Static addresses can be IPv4 or IPv6.
If you use IPv4 and IPv6 for the management node Eth0 (management network interface), each managed chassis and chassis component must have an IPv4 address.
IPv6 ULAs meet IBM Flex System network requirements. A ULA specifies an IP address that is globally unique, and is intended for local communications.
Attention: If the IPv6 ULA option on the Management Domain page is selected when a chassis is managed, the management software will overwrite any static or DHCP IPv6 address that was set previously on a Chassis Management Module (CMM). The IPv6 address for the IBM Flex System management node must have the same 64-bit prefix as the IPv6 address for the chassis CMMs.
Note:
- A specified prefix or global ID must be unique. The default value is generated based on an internal time stamp.
- A valid IPv6 address must be assigned to a managed resource before you can use Configuration Patterns to configure settings for a resource.
If the Chassis Management Module (CMM) and compute nodes are set up to use DHCP, and the CMM loses connectivity to the network, the CMM attempts to acquire a new IP address when network connectivity is restored. The compute nodes will not attempt to acquire an IP address again; they will continue to use their original IP addresses. Therefore, if you experience network problems on compute nodes after connectivity between the CMM and the network is restored, you might have to reset the service processor on each of the compute nodes in the chassis (including the management node). See the "Connectivity problems" topic in the Troubleshooting section of the documentation for your compute node for more information.
If you are using centralized user management mode, be aware of a potential problem with using DHCP. If your network interface for the management network is configured to use DHCP, the management interface IP address might change when the DHCP lease expires. If the IP address changes, you must unmanage the chassis, and then re-manage the chassis. To avoid this problem, either change the management interface to a static IP address, or make sure that the DHCP server configuration is set so that the DHCP address is based on a MAC address or that the DHCP lease does not expire.
If you are using centralized user management mode, make sure that you change the user management mode to decentralized before you change the management network (Eth0) IP address. See Changing an IBM Flex System Manager management node IP address for more information.
The management software can manage an Flex System Enterprise Chassis that is in a different geographic location than the management node, if the remote chassis is on the same management network. However, the procedure that is required to manage a remote chassis differs from the procedure required to manage a chassis that is on the same network subnet as the management node. See Managing a remote chassis for more information.