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Chapter 5 # External Addressing For a description of the options for connecting nonpeer nodes to the cluster network, see the following sections: Introduction to External Addressing External Addressing Scheme Connecting Nonpeer Nodes Directly to a Cluster Network Connecting Nonpeer Nodes to the Cluster Through Additional Physical Interfaces Connecting Nonpeer Nodes to the Cluster Network Through a Router ## Introduction to External Addressing An external network communicates with a cluster running the Foundation Services to perform one or more of the following tasks: Access one or more of the Foundation Services, such as the Reliable NFS service Access services provided by user applications Retrieve cluster information and statistics from the Node Management Agent Debug and maintain the cluster Install software from a build server or an installation server Install software from a development host The external network can be an Ethernet, ATM, or any other network type supported by the Solaris operating system. The addressing scheme used by the cluster network is classless. The IP addresses of peer nodes can be in a private network or a public network. An external network can connect to a cluster network in the following ways: Directly to the cluster network If the cluster IP addresses are in a private network, logical interfaces must be created to connect the external network to the cluster network. If the cluster IP addresses are in the same subnetwork as the external network, it is not necessary to create logical interfaces. Through additional physical interfaces on the peer nodes Through a router ## External Addressing Scheme External addresses have no inherent relationship to internal cluster addresses. External addresses are flexible. They can be single addresses, or multiple addresses combined using IP multipathing. They can be IPv4 or IPv6. ### Floating External Addresses A logical address assigned to an interface that connects the master node to an external network is called a floating external address. The Node State Manager (NSM) uses Cluster Membership Manager notifications to determine when a node is promoted to or demoted from the master role. When a node is promoted to the master role, the NSM configures a floating external address for one of the node's external interfaces. When a node is demoted from the master role, the NSM unconfigures the floating external address. The floating external address enables clients on an external network to access the master node. Because the floating external address is always configured on the master node, clients on an external network can always access the master node, even after failover and switchover. The NSM can be used for tasks other than address management. For information about how to configure the NSM, see the `nhnsmd`(1M) and `nhfs.conf`(4) man pages. ## Connecting Nonpeer Nodes Directly to a Cluster Network This section describes how a nonpeer node can be connected directly to a cluster network. Connecting a nonpeer node directly to the cluster network is disadvantageous for the following reasons: Internal traffic can leave the cluster network, compromising security. External traffic can enter the cluster network, reducing network performance. If the external network is connected to one of the cluster networks only, the traffic on the two cluster network paths can become asymmetric. This could affect the performance of the redundant transport mechanism provided by CGTP. Figure 5-1 and Figure 5-2 show examples of how a nonpeer node can be connected directly to a cluster network. In Figure 5-1, the nonpeer node is connected to the `hme` 0 interface of each peer node. Each `hme` 0 interface has a logical interface called `hme` 0:100, configured with an address in the public IP address space. The nonpeer node can access the cluster network through these logical interfaces. Figure 5-1 Example of a Nonpeer Node Connected Directly to a Cluster Network Using a Private IP Address Space Figure 5-2 shows the same cluster as Figure 5-1. In Figure 5-2 the cluster network uses a public IP address space. The nonpeer node is connected directly to the cluster network without the use of logical interfaces. Figure 5-2 Example of a Nonpeer Node Connected Directly to a Cluster Network Using a Public IP Address Space ### Addressing a Shared Cluster Network and External Network Table 5-1 shows the IP addresses of the master node in Figure 5-1. In addition to the addresses shown in Figure 5-1, the master node has a floating address for each interface. The Node State Manager configures the floating external address, `hme` 0:101. Table 5-1 Example IP Addresses for a Master Node With a Logical Interface Configured for External Access
Address Type | Interface | IP Address
--- | --- | ---
Master Node Addresses | `hme` 0 | `10.200.1.10`
`hme` 1 | `10.200.2.10`
`cgtp` 0 | `10.200.3.10`
External Address | `hme` 0:100 | `192.168.1.10`
Floating Addresses | `hme` 0:1 | `10.200.1.1`
`hme` 1:1 | `10.200.2.1`
`cgtp` 0:1 | `10.200.3.1`
Floating External Address | `hme` 0:101 | `192.168.1.1`
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