High Availability And Failover Considerations, 7 of 8

Failover Options in the Private Network Infrastructure

The Private Network Infrastructure is the network used by Oracle Internet Directory and its back-end components to communicate with each other. In cases where Oracle Internet Directory is deployed on the Internet, Oracle Corporation recommends that this network be physically different from the network used to serve client requests. In cases where Oracle Internet Directory is deployed over an Intranet, the same LAN may be used, but Oracle Internet Directory components should have dedicated bandwidth with the help of a network switch. Because Oracle Internet Directory depends on the Private Network Infrastructure for its communications, you must take adequate precautions to guarantee availability in the event of failures in the Private Network. Some of the options available in this area are:

IP Address Takeover (IPAT)

IP address takeover feature is available on many commercial clusters. This feature protects an installation against failures of the Network Interface Cards (NICs). In order to make this mechanism work, installations must have two NICs for each IP address assigned to a server. Both the NICs must be connected to the same physical network. One NIC is always active while the other is in a standby mode. The moment the system detects a problem with the main adapter, it immediately fails over to the standby NIC. Ongoing TCP/IP connections are not disturbed and as a result clients do not notice any downtime on the server.

Redundant Links

Since all networks (with the exception of wireless networks) are comprised of wires going from one location to the other, there is a distinct possibility that someone might unintentionally disconnect a wire that is used to link a client computer to a server computer. If you want to take such precautions, use NICs and hubs/switches that come with the capability to use redundant links in case of a link level failure.