IBM PureFlex System and IBM Flex System Products and Technology

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6.4 High availability and redundancy

You might need to have continuous access to your network services and applications.

Providing high availability for client network resources is a complex task that involves fitting

multiple “pieces” together on a hardware and a software level. One HA component is to

provide network infrastructure availability.

Network infrastructure availability can be achieved by implementing certain techniques and

technologies. Most of them are widely used standards, but some of them are specific to

Enterprise Chassis. This section addresses the most common technologies that can be

implemented in an Enterprise Chassis environment to provide high availability for network

infrastructure.

In general, a typical LAN infrastructure consists of server NICs, client NICs, and network

devices such as Ethernet switches and cables that connect them together. The potential

failures in a network include port failures (both on switches and servers), cable failures, and

network device failures.

To provide high availability and redundancy, avoid or minimize single points of failure. Provide

redundancy for network equipment and communication links by using:

򐂰 Two Ethernet ports on each compute node (LOM enabled node)

򐂰 Two or four I/O modules on each node (four on double wide nodes)

򐂰 Two or four ports on I/O expansion cards on each compute node

򐂰 Two Ethernet switches per dual port for device redundancy

For more information about connection topology between I/O adapters and I/O modules, see

4.10, “I/O modules” on page 92.

Implement technologies that provide automatic failover in case of any failure. Automatic

failover can be configured by using certain feature protocols that are supported by network

device, together with server-side software.

Consider implementing these technologies, which can help achieve a higher level of

availability in an Enterprise Chassis network solution (depending on your network

architecture):

򐂰 Spanning Tree Protocol

򐂰 Layer 2 failover (also known as Trunk Failover)

򐂰 Virtual Link Aggregation Groups

򐂰 Virtual Router Redundancy Protocol

򐂰 Routing Protocol such as Router Information Protocol (RIP) or Open Shortest Path First

(OSPF)