a. See "OSA port names" on page 74 for more information about port names. Linking a Linux guest to the VSWITCH is exactly the same as linking a guest to a Guest LAN. See 4.6.4, "Create a virtual Network Interface Card" on page 100 for the description of that process. 4.9.4 VSWITCH failover support Failover support for Virtual Switches provides recovery for controller failures and OSA-Express port failures. A redundant system would use two or three virtual controllers and two or three separate OSA cards. If one controller fails, another controller takes over. A port on each card is plugged into an access port on the same subnet, which can be in separate physical switches if the switches are linked together, or trunk ports with identical configurations. If one OSA port fails, traffic is switched to use another OSA port. On a z/VM 5.1 system, when a VSWITCH is defined with multiple OSA devices and multiple virtual controllers are available, z/VM pairs backup controllers to the backup OSA devices, attaches them to the controllers, and performs as much initialization as possible for the backup ports. This reduces the elapsed time to recover from an error. In the event of an OSA or controller failure, data transfer to the network is