Sun Cluster Concepts Guide for Solaris OS

Public Network Adapters and Internet Protocol (IP) Network Multipathing

Clients make data requests to the cluster through the public network. Each cluster node is connected to at least one public network through a pair of public network adapters.

Solaris Internet Protocol (IP) Network Multipathing software on Sun Cluster provides the basic mechanism for monitoring public network adapters and failing over IP addresses from one adapter to another when a fault is detected. Each cluster node has its own Internet Protocol (IP) Network Multipathing configuration, which can be different from the configuration on other cluster nodes.

Public network adapters are organized into IP multipathing groups (multipathing groups). Each multipathing group has one or more public network adapters. Each adapter in a multipathing group can be active. Alternatively, you can configure standby interfaces that are inactive unless a failover occurs.

The in.mpathd multipathing daemon uses a test IP address to detect failures and repairs. If a fault is detected on one of the adapters by the multipathing daemon, a failover occurs. All network access fails over from the faulted adapter to another functional adapter in the multipathing group. Therefore, the daemon maintains public network connectivity for the node. If you configured a standby interface, the daemon chooses the standby interface. Otherwise, daemon chooses the interface with the least number of IP addresses. Because the failover occurs at the adapter interface level, higher-level connections such as TCP are not affected, except for a brief transient delay during the failover. When the failover of IP addresses completes successfully, ARP broadcasts are sent. Therefore, the daemon maintains connectivity to remote clients.

Note –

Because of the congestion recovery characteristics of TCP, TCP endpoints can experience further delay after a successful failover. Some segments might have been lost during the failover, activating the congestion control mechanism in TCP.

Multipathing groups provide the building blocks for logical hostname and shared address resources. You can also create multipathing groups independently of logical hostname and shared address resources to monitor public network connectivity of cluster nodes. The same multipathing group on a node can host any number of logical hostname or shared address resources. For more information about logical hostname and shared address resources, see the Sun Cluster Data Services Planning and Administration Guide for Solaris OS.

Note –

The design of the Internet Protocol (IP) Network Multipathing mechanism is meant to detect and mask adapter failures. The design is not intended to recover from an administrator's use of ifconfig(1M) to remove one of the logical (or shared) IP addresses. The Sun Cluster software views the logical and shared IP addresses as resources that are managed by the RGM. The correct way for an administrator to add or remove an IP address is to use scrgadm(1M) to modify the resource group that contains the resource.

For more information about the Solaris implementation of IP Network Multipathing, see the appropriate documentation for the Solaris Operating System that is installed on your cluster.

Operating System Release 


Solaris 8 Operating System 

IP Network Multipathing Administration Guide

Solaris 9 Operating System 

Chapter 1, IP Network Multipathing (Overview), in IP Network Multipathing Administration Guide

Solaris 10 Operating System 

Part VI, IPMP, in System Administration Guide: IP Services