Public Network FAQ

• What public network adapters does the SunPlex system support?

  Currently, the SunPlex system supports Ethernet (10/100BASE-T and 1000BASE-SX Gb) public network adapters. Because new interfaces might be supported in the future, check with your Sun sales representative for the most current information.

• What is the role of the MAC address in failover?

  When a failover occurs, new Address Resolution Protocol (ARP) packets are generated and broadcast to the world. These ARP packets contain the new MAC address (of the new physical adapter to which the node failed over) and the old IP address. When another machine on the network receives one of these packets, it flushes the old MAC-IP mapping from its ARP cache and uses the new one.

• Does the SunPlex system support setting local-mac-address?=true in the OpenBoot^TM PROM (OBP) for a host adapter?

  No, this variable is not supported.

• How much delay can I expect when NAFO performs a switchover between the active and backup adapter?

  The delay could be several minutes. This is because when a NAFO switchover is done, it involves sending out a gratuitous ARP. However, there is no guarantee that the router between the client and the cluster will use the gratuitous ARP. So, until the ARP cache entry for this IP address on the router times out, it is possible that it could use the stale MAC address. A second reason for delay might be that both NAFO adapters are connected to an Ethernet switch. When a NAFO switchover is done, one of the NAFO adapters is unplumbed and the second adapter is plumbed. The Ethernet switch would now have to disable a port and enable a different port, which might take some time. Also, with Ethernet, speed negotiation takes place between the switch and the newly enabled adapter, which takes time.Finally, after a switchover is done, NAFO does some minimal sanity checking on the newly enabled adapter to verify that everything works fine.