FreeBSD 9.3 : how to configure carp

Here is how to configure carp on FreeBSD 9.3.

Reference

https://www.freebsd.org/doc/handbook/carp.html

Two FreeBSD 9.3 machines are running as virtual machines and these VMs have two vNICs.

SW-  em0 VM1 em1 -------|

| ---   em0 VM2 em1  ---- SW

edit /boot/loader.conf so that the OS loads carp module when booting.

root@bsd93-vm1:~ # cat /boot/loader.conf if_carp_load="YES"

reboot the OS

make sure the OS is loading carp module.

root@bsd93-vm1:~ # kldstat Id Refs Address            Size     Name 1    3 0xffffffff80200000 1611638  kernel 2    1 0xffffffff81812000 10db0    if_carp.ko

on the VM1

add carp0 device to em1

root@bsd93-vm1:~ # cat /etc/rc.conf hostname="bsd93-vm1" keymap="jp.106x.kbd" ifconfig_em0="DHCP" sshd_enable="YES" # Set dumpdev to "AUTO" to enable crash dumps, "NO" to disable dumpdev="AUTO" unbound_enable="YES" ifconfig_em1="inet 192.168.1.3 netmask 255.255.255.0" cloned_interfaces="carp0" ifconfig_carp0="vhid 1 pass testpass 192.168.1.50/24"

on the VM2

root@bsd93-vm2:~ # cat /etc/rc.conf hostname="bsd93-vm2" keymap="jp.106x.kbd" ifconfig_em0="DHCP" sshd_enable="YES" # Set dumpdev to "AUTO" to enable crash dumps, "NO" to disable dumpdev="AUTO" unbound_enable="YES" ifconfig_em1="inet 192.168.1.4 netmask 255.255.255.0" cloned_interfaces="carp0" ifconfig_carp0="vhid 1 advskew 100 pass testpass 192.168.1.50/24"

reboot VM1 and VM2.

Both VM has same IP 192.168.1.50 on carp0 device.

Backup box also grabs the VIP when that machine is in backup state.

VM1 is master.

root@bsd93-vm1:~ # ifconfig -a em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=209b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC> ether 52:54:00:16:a6:9e inet 192.168.11.20 netmask 0xffffff00 broadcast 192.168.11.255 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> media: Ethernet autoselect (1000baseT <full-duplex>) status: active em1: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=209b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC> ether 52:54:00:2c:8b:7b inet 192.168.1.3 netmask 0xffffff00 broadcast 192.168.1.255 inet6 fe80::5054:ff:fe2c:8b7b%em1 prefixlen 64 scopeid 0x3 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> media: Ethernet autoselect (1000baseT <full-duplex>) status: active lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384 options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6> inet6 ::1 prefixlen 128 inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4 inet 127.0.0.1 netmask 0xff000000 nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL> carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500 inet 192.168.1.50 netmask 0xffffff00 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> carp: MASTER vhid 1 advbase 1 advskew 0 root@bsd93-vm1:~ #

on the VM2

VM2 is backup.

root@bsd93-vm2:~ # ifconfig -a em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=209b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC> ether 52:54:00:de:6d:92 inet 192.168.11.17 netmask 0xffffff00 broadcast 192.168.11.255 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> media: Ethernet autoselect (1000baseT <full-duplex>) status: active em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=209b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC> ether 52:54:00:e1:ea:69 inet 192.168.1.4 netmask 0xffffff00 broadcast 192.168.1.255 inet6 fe80::5054:ff:fee1:ea69%em1 prefixlen 64 scopeid 0x3 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> media: Ethernet autoselect (1000baseT <full-duplex>) status: active lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384 options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6> inet6 ::1 prefixlen 128 inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4 inet 127.0.0.1 netmask 0xff000000 nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL> carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500 inet 192.168.1.50 netmask 0xffffff00 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> carp: BACKUP vhid 1 advbase 1 advskew 100

VM1 ( 192.168.1.3 ) is sending advertisement packets every second.

root@bsd93-vm2:~ # tcpdump -i em1 -n carp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on em1, link-type EN10MB (Ethernet), capture size 65535 bytes 17:23:10.707902 IP 192.168.1.3 > 224.0.0.18: VRRPv2, Advertisement, vrid 1, prio 0, authtype none, intvl 1s, length 36 17:23:11.717968 IP 192.168.1.3 > 224.0.0.18: VRRPv2, Advertisement, vrid 1, prio 0, authtype none, intvl 1s, length 36

reboot the VM1.

VM2 is master

root@bsd93-vm2:~ # ifconfig carp0 carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500 inet 192.168.1.50 netmask 0xffffff00 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> carp: MASTER vhid 1 advbase 1 advskew 100

VM1 is backup.

root@bsd93-vm1:~ # ifconfig carp0 carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500 inet 192.168.1.50 netmask 0xffffff00 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> carp: BACKUP vhid 1 advbase 1 advskew 0

[ make high availability of DNS “unbound” with CARP ]

With CARP, backup machine can grab VIPs when that machine is in backup state, so you do not need to restart unbound process when master-backup state has changed.

VM1

unbound.conf

interface: 192.168.1.50        interface: 127.0.0.1

VM2

unbound.conf

interface: 192.168.1.50        interface: 127.0.0.1

When VM2 is master

root@bsd93-vm2:~ # ifconfig carp0 carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500 inet 192.168.1.50 netmask 0xffffff00 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> carp: MASTER vhid 1 advbase 1 advskew 100 # /var/log/messages Sep  7 17:57:56 bsd93-vm2 unbound: [858:0] info: 192.168.1.100 www.google.com. A IN

When VM1 is master

root@bsd93-vm1:~ # ifconfig carp0 carp0: flags=49<UP,LOOPBACK,RUNNING> metric 0 mtu 1500 inet 192.168.1.50 netmask 0xffffff00 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> carp: MASTER vhid 1 advbase 1 advskew 0 # /var/log/messages Sep  7 17:58:45 bsd93-vm1 kernel: carp0: link state changed to UP Sep  7 17:59:25 bsd93-vm1 unbound: [853:0] info: 192.168.1.100 www.google.com. A IN