Specifications

128 IBM Flex System p260 and p460 Planning and Implementation Guide
5.4 Configuring redundancy
Your environment might require continuous access to your network services and
applications. Providing highly available (HA) network resources is a complex task
that involves the integration of multiple hardware and software components. One
HA component is to provide network infrastructure availability.
This availability is required for both network and SAN connectivity.
5.4.1 Network redundancy
Network infrastructure availability can be achieved by implementing certain
techniques and technologies. Most of these items are widely used standards, but
several are specific to the IBM Flex System Enterprise Chassis. This section
describes the most common technologies that can be implemented in an IBM
Flex System environment to provide a highly available network infrastructure.
In general, a typical LAN infrastructure consists of server NICs, client NICs, and
network devices, such as Ethernet switches and that cables that connect them.
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, that is, provide redundancy for
network equipment and communication links. The IBM Flex System
Enterprise Chassis has built-in redundancy:
– Two or four ports on I/O expansion cards on each compute node
– Two separate communication paths to I/O modules through dual
midplane connections
– Two I/O module bays per dual port for device redundancy
For a sample connection topology between I/O adapters and I/O modules,
see Chapter 3, “Systems management”, of IBM PureFlex System and IBM
Flex System Products & Technology, SG24-7984.
Implement technologies that provide automatic failover in the case of any
failure. This implementation can be done by using certain feature protocols
that are supported by network devices, together with server-side software.
Consider implementing the following technologies, which can help you to
achieve a higher level of availability in an IBM Flex System network solution
(depending on your network architecture):
– Spanning Tree Protocol
– Layer 2 failover (also known as Trunk Failover)