TAILIEUCHUNG - Professional Information Technology-Programming Book part 133

Tham khảo tài liệu 'professional information technology-programming book part 133', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Assuming you have only one network interface that needs failover protection the first thing you need to do on the gateway host and backup systems is create a carp0 interface. You can easily do this via the ifconfig program from the command line but it s better to automatically create the interface at boot time. To do that you need to create an etc file on the primary host and put this into it vhid 1 carpdev em0 pass yourpass netmask In the above example the vhid parameter identifies the redundancy group. You can choose a number from 1 to 255 but 1 is easiest especially if you have only one group of machines to protect. The carpdev parameter identifies the local network interface that needs failover protection. In essence you re providing failover for interfaces which in turn provides failover for machines. In the example em0 is the device node of the network interface yours will almost certainly be different. The pass parameter defines a password which is followed in in the example by yourpass. This is a password that must be in the configuration of every CARP-enabled machine in the group. is the IP address that the primary and backup hosts will share. The netmask parameter defines the subnet mask of . Each backup machine in the group must have a similar but slightly different CARP configuration vhid 1 carpdev rl0 pass yourpass netmask advskew 100 In this example there are two differences. First the carpdev variable is rl0 instead of em0 because the backup machine has a different network card that uses a different device node. If the two machines were physically identical their interface nodes would match. Second there is a new variable advskew. This setting lags the backup machine s availability advertisement so that it is broadcast significantly less often than the primary host. This setting is what defines the primary and backup hosts the machine with the lowest advskew is .