How NetBackup uses the directives to determine which network to use
Each host has an internal table of preferred network rules that NetBackup consults before it selects a network interface to use for communication with another host. The table includes every interface-IP address combination available to the selected host. Based on the Preferred NetBackup directives, the table indicates to NetBackup whether or not the host is allowed to use a given network.
This topic uses the example of two multihomed servers (Server_A and Server_B) as shown in Figure: Multihomed servers example. Server A is considering which addresses it can use to access Server_B, given the Preferred Network directives configured on Server_A.
When Preferred Network directives are used to place restrictions on targets, they are added from the perspective of the server making the connection. The directives on Server_A affect its preferences as to which Server_B addresses it can use.
Figure: From Server_A's perspective: Available IP addresses on Server_B when no directives are indicated on Server_A shows a table for Server_B. Server_B has multiple network interfaces, some of which have multiple IP addresses. In the table, yes indicates that NetBackup can use the network-IP combination as a source. In this example, no directives have been created for the host. Since no networks are listed in the Preferred Network properties, any network-IP combinations can be used for communication.
Note:
The following topic shows the bptestnetconn output for this example configuration:
See bptestnetconn utility to display Preferred Network information.
Figure: From Server_A's perspective: Available IP addresses on Server_B when no directives are indicated on Server_A
Figure: From Server_A's perspective: Available IP addresses on Server_B when directives to use IPv6 addresses only are indicated on Server_A shows a table for the same host (Server_B). Now, the Preferred Network properties are configured so that all IPv4 addresses are excluded from selection consideration by NetBackup. All NetBackup traffic is to use only IPv6 addresses.
Figure: From Server_A's perspective: Available IP addresses on Server_B when directives to use IPv6 addresses only are indicated on Server_A
The following topics describe various configurations: