IBM AIX HACMP SG24-5131-00, Hardware User Manual

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IBM Certification Study Guide AIX HACMP
3.2 Network Connection and Testing
The following sections describe important aspects of network connection and
testing.
3.2.1 TCP/IP Networks
Since there are several types of TCP/IP Networks available within HACMP,
there are several different characteristics and some restrictions on them.
Characteristics like maximum distance between nodes have to be
considered. You don’t want to put two cluster nodes running a mission-critical
application in the same room for example.
3.2.1.1 Cabling Considerations
Characteristics of the different types of cable, their maximum length, and the
like are beyond the scope of this book. However, for actual planning of your
clusters, you have to check whether your network cabling allows you to put
two cluster nodes away from each other, or even in different buildings.
There’s one additional point with cabling, that should be taken care of.
Cabling of networks often involves hubs or switches. If not carefully planned,
this sometimes introduces another single point of failure into your cluster. To
eliminate this you should have at least two hubs.
As shown in Figure 9, failure of a hub would not result in one machine being
disconnected from the network. In that case, a hub failure would cause either
both service adapters to fail, which would cause a
swap_adapter event, and
the standby adapters would take over the network, or both standby adapters
would fail, which would cause
fail_standby events. Configuring a notify
method for these events can alert the network administrator to check and fix
the broken hub.