Common Address Redundancy Protocol

The Common Address Redundancy Protocol or CARP is a protocol which allows multiple hosts on the same local network to share a set of IP addresses. Its primary purpose is to provide failover redundancy. For example, if there is a single computer running a packet filter, and it goes down, then either the networks on either side of the packet filter can no longer communicate with each other, or they communicate without any packet filtering. If, however, there are two computers running a packet filter, running CARP, then if one fails, the other will take over, and computers on either side of the packet filter will not be aware of the failure, so operation will continue as normal. In order to make sure the new master operates the same as the old one, pfsyncd is used. In some configurations CARP can also provide load balancing functionality.

Installatie

Eerst de kernel recompilen en voeg toe:

device carp

Configureren

Nieuwe CARP aanmaken:

ifconfig carp0 create

Configuratie Server A:
Het bestand /etc/sysctl.conf aanpassen

net.inet.carp.preempt=1
net.inet.carp.allow=1
net.inet.carp.log=1
net.inet.carp.arpbalance=1

Het bestand /etc/rc.conf aanpassen

hostname="hosta.example.org"
cloned_interfaces="carp0"
network_interfaces="fxp0 carp0"
ifconfig_carp0="up vhid 1 advskew 3 pass testpass 192.168.1.145"

Het bestand ee /etc/rc.local aanpassen

ifconfig carp0 up &

Configuratie Server B:
Het bestand /etc/sysctl.conf aanpassen

net.inet.carp.preempt=1
net.inet.carp.allow=1
net.inet.carp.log=1
net.inet.carp.arpbalance=1

Het bestand /etc/rc.conf aanpassen

hostname="hostb.example.org"
cloned_interfaces="carp0"
network_interfaces="ed0 carp0"
ifconfig_carp0="up vhid 1 advskew 3 pass testpass 192.168.1.145"

Het bestand ee /etc/rc.local aanpassen

ifconfig carp0 up &

Na een reboot is CARP gestart.

Links

• Zie ook: CARP website
• Zie ook: FreeBSD Handbook