ExpressCluster X 2.0 for Windows Reference Guide - Nec

Determining virtual IP address
Section II Resource details
Understanding virtual IP resources
An IP address used as a virtual IP address should satisfy the following conditions:
� The IP address should not be within the network address of the LAN to which the cluster
belongs.
� The IP address should not conflict with existing network addresses.
Select one of the following allocation methods to meet the requirements above:
� Obtain a new network IP address for virtual IP address and allocate virtual IP address.
� Determine a network IP address from private IP address space and allocate virtual IP address.
The following procedures are given as an example.
Controlling path
• Select one network address from 192.168.0 to 192.168.255 for virtual IP address.
• Allocate up to 64 host IP addresses for virtual IP address from the network address you
have selected. (For example, select the network address 192.168.10 and allocate two host
IP addresses: 192.168.10.1 and 192.168.10.254)
• Specify 255.255.255.0 to net mask of the virtual IP address.
• Private IP addresses are addresses for a closed network and they cannot be accessed
using virtual IP address from outside of the network through internet providers.
• Do not disclose path information of private IP addresses outside the organization.
• Adjust the private IP addresses to avoid conflict with other address.
To access to a virtual IP address from a remote LAN, path information of the virtual IP address
must be effective to all routers on the path from the remote LAN to the LAN for cluster server.
To be specific, the following condition must be satisfied:
� Routers on the cluster servers LAN interpret host RIP.
� Routers on the path from a cluster server to the remote server have the dynamic routing
settings or information on the virtual IP address routes has configured as static routing
settings.
Requirement to use virtual IP address
Environments where virtual IP address can be used
Virtual IP addresses can be accessed from the machines listed below. Virtual IP address
mechanism functions properly even in a LAN where switching hubs are used. However, when a
server goes down, TCP/IP that has been connected will be disconnected.
When using virtual IP addresses with a switching HUB that cannot be configured to create a host
routing table by receiving host RIP, you need to reserve one new network address and configure
virtual IP addresses so that the IP address of each server belongs to a different network address.
� Cluster servers that belong to the same LAN that the server the virtual IP activates
belongs to
Virtual IP addresses can be used if the following conditions are satisfied:
• Machines that can change the path by receiving RIP packets.
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