Cluster I/O Protocols (CIP) Configuration and Management Manual (H06.16+, J06.05+)

• “Fail Back (Restore Behavior)” (page 44)
• “Failover Failure” (page 45)
• “CLIM Startup Behavior” (page 45)
Interface Names and Resources
On the NonStop system, interfaces are given a unique name within a Provider by pre-pending the
CLIM home interface name with the CLIM name and a period (.). For instance: n1002531.eth4
or n1012542.bond0.
Physical and bonded interfaces are tied to physical ports and so cannot move in a literal sense.
However, many of the resources associated with an interface can be moved from one interface to
another, which is how failover works. The resources are given the name of their home interface,
so one can say that n1002531.eth2 is currently located at n1012542.eth4, meaning that the
resources configured or created for interface n1002531.eth2 have been moved to n1012542.eth4.
The NonStop OS contains an interface table that gives the current location of each interface name.
On the CLIM, each interface can contain resources from either none, one, or two interface names.
The normal state is to contain only the home resources. If CLIM resources have failed over, the
CLIM has no resources and the interface is down. If the failover interface has failed, the home
CLIM contains both the home resources and the visiting resources from the failover interface. Visiting
resources cannot be present unless the home resources are also present.
Table 1: Interface Resource Failover Behavior summarizes the interface resources, how they are
created, and how they are migrated during failover. Bonded interfaces share many of their resources
among multiple physical interfaces, making intra-CLIM failover a matter of just letting the others
take over the load. CLIM-to-CLIM failover requires actual migration of resources to a new location.
Table 1 Interface Resource Failover Behavior
CLIM-to-CLIM FailoverIntra-CLIM FailoverCreated byResource
Not migratedShared, migrated, or not
migrated depending on
bonding mode
Hardware parameterMAC address
MigratedSharedConfigurationStatic IPv4 addresses
MigratedSharedConfigurationStatic IPv6 addresses
MigratedSharedProtocolLink-local and
autoconfigured IPv6
addresses
MigratedSharedApplicationsJoined-group multicast IP
addresses
MigratedSharedProtocolSolicited-node multicast IP
addresses
MigratedSharedApplicationsUDP sockets
MigratedSharedApplicationsTCP listening sockets
MigratedSharedConfigurationStatic routes
Not migrated, re-created as
needed
SharedProtocolsDynamic routes
Not migrated, must be
configured the same on the
failover CLIM
SharedConfigurationStatic ARP entries
Not migrated, re-created as
needed
SharedProtocolDynamic ARP entries
40 Overview