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Configuring Network IP MultiPathing (IPMP)
IP MultiPathing groups are used to provide IP addresses that will remain available in the event
of an IP interface failure (such as a physical wire disconnection or a failure of the connection
between a network device and its switch) or in the event of a path failure between the system
and its network gateways. The system detects failures by monitoring the IP interface's
underlying datalink for link-up and link-down notifications, and optionally by probing using
test addresses that can be assigned to each IP interface in the group, described below. Any
number of IP interfaces can be placed into an IPMP group so long as they are all on the same
link (LAN, IB partition, or VLAN), and any number of highly-available addresses can be
assigned to an IPMP group.
Each IP interface in an IPMP group is designated either active or standby:
Active - The IP interface will be used to send and receive data so long as IPMP has
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determined it is functioning correctly.
Standby - The IP interface will only be used to send and receive data if an active interface
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(or a previously activated standby) stops functioning.
Multiple active and standby IP interfaces can be configured, but each IPMP group must be
configured with at least one active IP interface. IPMP will strive to activate as many standbys
as necessary to preserve the configured number of active interfaces. For example, if an IPMP
group is configured with two active interfaces and two standby interfaces and all interfaces are
functioning correctly, only the two active interfaces will be used to send and receive data. If an
active interface fails, one of the standby interfaces will be activated. If the other active interface
fails (or the activated standby fails), the second standby interface will be activated. If the active
interfaces are subsequently repaired, the standby interfaces will again be deactivated.
IP interface failures can be discovered by either link-based detection or probe-based detection
(i.e., a test address is configured).
If probe-based failure detection is enabled on an IP interface, the system will determine which
target systems to probe dynamically. First, the routing table will be scanned for gateways
(routers) on the same subnet as the IP interface's test address and up to five will be selected. If
no gateways on the same subnet were found, the system will send a multicast ICMP probe (to
224.0.01. for IPv4 or ff02::1 for IPv6) and select the first five systems on the same subnet that
respond. Therefore, for network failure detection and repair using IPMP, you should be sure
that at least one neighbor on each link or the default gateway responds to ICMP echo requests.
IPMP works with both IPv4 and IPv6 address configurations. In the case of IPv6, the interface's
link-local address is used as the test address.
Do not use probe-based failure detection when there no systems (other than the cluster
Note -
peer) on the same subnet as the IPMP test addresses that are configured to answer ICMP echo
requests.
Changing the Multihoming Property to Strict (CLI)
Configuring the Appliance
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