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IPv4 Test AddressesThe in.mpathd multipathing daemon requires a test IP address for detecting failures and repairs. You must use a routeable address for this IP address. The subnet prefix of the address must be known to any routers present on the link. You use the ifconfig command's new -failover option to configure a test address. Use the following syntax to configure a test address:
For <other-parameters>, use the parameters that are required by your configuration. See the ifconfig(1M) man page for descriptions. How to Configure a Multipathing Interface Group With Two Interfaces shows the steps that you perform for an IPv4 test address. For example, if you wanted to do the following configuration:
Type the following command:
Note - You must mark an IPv4 test address as deprecated to prevent applications from using the test address. See How to Configure a Multipathing Interface Group With Two Interfaces. Use failover without the dash to turn on the failover attribute of the address. Note - All test IP addresses in a multipathing group must use the same network prefix. The test IP addresses must belong to a single IP subnet. IPv6 Test AddressesTo configure an IPv6 test address, you use the link-local address, because link-local addresses are tied to the physical interface. Thus, you do not need a separate IP address in the IPv6 situation. For IPv6, the -failover option has the following syntax:
How to Configure a Multipathing Interface Group With Two Interfaces shows the steps that you perform for an IPv6 test address. When a multipathing group has both IPv4 and IPv6 plumbed on all the group's interfaces, you might not need a separate IPv4 test address. The in.mpathd daemon can probe the interfaces by using an IPv6 link-local address. IPv6 link-local addresses are created when IPv6 is plumbed. Use failover without the dash to turn on the failover attribute of the address. Note - The only valid IPv6 test address is the link-local address. Preventing Applications From Using Test AddressesAfter you have configured a test address, you need to ensure that this address is not used by normal applications. If you let applications use the test address, applications fail, because test addresses do not fail over during the failover operation. To ensure that IP does not pick the test address for normal applications, you mark the test address deprecated by using the ifconfig command. This parameter has the following syntax:
IP does not pick a deprecated address as a source address for any communication, unless the applications explicitly bind to the address. Only in.mpathd explicitly binds to such an address. See How to Configure a Multipathing Interface Group With Two Interfaces. Because link-local addresses are not present in the name service, DNS, NIS, and NIS+, applications do not use link-local addresses for communication. Consequently, you do not need to mark IPv6 test addresses as deprecated. Note - You must not mark IPv6 link-local addresses as deprecated. Use the -deprecated option to turn off the deprecated attribute of the address. Note - IPv4 test addresses should not be placed in the name service tables, DNS, NIS, and NIS+. In IPv6, link-local addresses are used as test addresses. In IPv6, link-local addresses are not normally placed in the name service tables. Autoconfigured IPv6 addresses are not preserved across system reboot. If you require that IP addresses be preserved across reboot, then applications should use static IP addresses. Using the hostname File to Configure Groups and Test AddressesYou can use the /etc/hostname.interface files to configure multipathing groups and test addresses. To configure a multipathing group by using the /etc/hostname.interface file, you can add a line to the file by using the following syntax:
For example, if you want to create the group test with the following configuration:
You add the following line to the /etc/hostname.hme0 file:
How to Configure a Multipathing Interface Group With Two Interfaces shows the steps that you perform to configure the IPv4 hostname file. For IPv6 setup, add a line to the /etc/hostname6.interface file by using the following syntax:
For example, to create a test group for hme0 with an IPv6 test address, add the following line to the /etc/hostname6.hme0 file:
How to Configure a Multipathing Interface Group With Two Interfaces shows the steps that you perform to configure the IPv6 hostname6 file. Configuring Standby InterfacesYou can configure multipathing groups with standby interfaces. As the name implies, the interface is considered a standby interface. The standby interface is not used unless some other interface in the group fails. A standby interface has an IFF_INACTIVE flag when the interface is not hosting any failover IP address. Consequently, when an active interface fails, the standby interface is always chosen for failover. After the standby interface is chosen, the IFF_INACTIVE flag is cleared on the standby interface. From that instant, the active standby interface is treated the same as other active interfaces. Some failures might not choose a standby interface. Instead, some failures might choose an active interface that hosts fewer IP addresses than the standby interface. The standby interface is not used to send normal data packets. Consequently, limited traffic flows on a standby interface. You must configure standby interfaces with a test address to ensure that probes are sent to determine if the interface is functional. If you do not configure standby interfaces with a test address, the interface is not chosen for failovers when another interface in the group fails. A standby interface might carry traffic under the following conditions:
Thus, the system does not normally select a standby interface, except for probes, unless the standby interface is explicitly chosen by an application. If some interface in the group fails, all network access is switched to the standby interface. To configure a standby interface, you use the ifconfig command's new standby parameter by using the following syntax:
How to Configure a Multipathing Group With One of the Interfaces a Standby Interface shows the steps that you perform. The in.mpathd daemon sends probes on the standby interface after a test address is configured on the standby interface. You should configure only test addresses on a standby interface. If any other address is added on the standby, the addition of this address fails. If a standby interface already has addresses other than test addresses, automatic failover of these addresses occurs to a different interface in the group. Only the test address remains, if a test address exists. Avoid configuring non-test address on a standby interface. You need to mark the address as a test address by using the ifconfig command's deprecated and -failover options before setting standby or setting up. To configure a test address on a standby interface, use the following syntax:
For <other-parameters>, use the parameters that are required by your configuration. See the ifconfig(1M) man page for descriptions. Note - Standby interfaces are not used for failover if no test address is configured on that interface. For example, if you want to create a test address with the following configuration:
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