Testing for Availability - Expert Oracle RAC Performance Diagnostics and Tuning - page 57

NIC Bonding
Using the parameter has benefits when there are multiple databases configured on the same cluster and when
the desire is to route each database's interconnect traffic on a separate private network. However, considering the
HA features, a better, more reliable method over the previous option would be to use the network interface card
(NIC) pairing or bonding functionality available at the O/S level. Multiple NICs can be paired to act as a single
logical entity.
NIC bonding or NIC pairing is a method of pairing multiple physical network connections into a single logical
interface. This logical interface will be used to establish a connection with the database server. By allowing all network
connections that are part of the logical interface to be used during communication, it provides load-balancing
capabilities that would otherwise not be available. In addition, when one of the network connections fails, the other
connection will continue to receive and transmit data, making it fault tolerant.
The first step in implementing the bonding functionality is to configure the bonding drivers. For example, in a
Linux environment, this is done by adding the following to the /etc/modules.conf file:

alias bond0 bonding
options bond0 miimon=100 mode=0

The configuration consists of two lines for each logical interface. The value miimon (media independent
interface monitor) is configured in milliseconds and represents the link monitoring frequency. Mode indicates the
type of configuration that will be deployed between the interfaces that are bonded or paired together and how the
physical interfaces that are part of the logical interface will be used. A value of 0 indicates that a round-robin policy
will be used and all interfaces will take turns in transmitting; Mode 1 indicates that one of the interfaces will be
configured as a backup device and Mode 2 indicates either of them would be used.
The next step is to configure the logical interfaces. Configuring the logical interface is to create the file
ifcfg-bond0 for the private logical interfaces in the /etc/sysconfig/network-scripts directory:

[root@prddb3 network-scripts]# more ifcfg-bond2
# Linux NIC bonding between eth24 and eth25
# Murali Vallath
# December-21-2013
DEVICE=bond2
BOOTPROTO=none
BROADCAST=192.30.0.255
IPADDR=192.30.0.96
NETMASK=255.255.255.0
NETWORK=192.30.0.0
ONBOOT=yes
USERCTL=no
TYPE=Ethernet

■ the /etc/sysconfig/network-scripts directory contains, by default, one configuration file per network
interface and all the interface assigned credentials such as ip address, subnet details, and so forth. Users should have
root privileges to complete this operation.

Note