:lastproofread: 2021-06-30 .. _high-availability: High availability ================= VRRP (Virtual Router Redundancy Protocol) provides active/backup redundancy for routers. Every VRRP router has a physical IP/IPv6 address, and a virtual address. On startup, routers elect the master, and the router with the highest priority becomes the master and assigns the virtual address to its interface. All routers with lower priorities become backup routers. The master then starts sending keepalive packets to notify other routers that it's available. If the master fails and stops sending keepalive packets, the router with the next highest priority becomes the new master and takes over the virtual address. VRRP keepalive packets use multicast, and VRRP setups are limited to a single datalink layer segment. You can setup multiple VRRP groups (also called virtual routers). Virtual routers are identified by a VRID (Virtual Router IDentifier). If you setup multiple groups on the same interface, their VRIDs must be unique if they use the same address family, but it's possible (even if not recommended for readability reasons) to use duplicate VRIDs on different interfaces. Basic setup ----------- VRRP groups are created with the ``set high-availability vrrp group $GROUP_NAME`` commands. The required parameters are interface, vrid, and address. minimal config .. code-block:: none set high-availability vrrp group Foo vrid 10 set high-availability vrrp group Foo interface eth0 set high-availability vrrp group Foo address 192.0.2.1/24 You can verify your VRRP group status with the operational mode ``run show vrrp`` command: .. code-block:: none vyos@vyos# run show vrrp Name Interface VRID State Last Transition ---------- ----------- ------ ------- ----------------- Foo eth1 10 MASTER 2s IPv6 support ------------ The ``address`` parameter can be either an IPv4 or IPv6 address, but you can not mix IPv4 and IPv6 in the same group, and will need to create groups with different VRIDs specially for IPv4 and IPv6. If you want to use IPv4 + IPv6 address you can use option ``excluded-address`` Address ------- The ``address`` can be configured either on the VRRP interface or on not VRRP interface. .. code-block:: none set high-availability vrrp group Foo address 192.0.2.1/24 set high-availability vrrp group Foo address 203.0.113.22/24 interface eth2 set high-availability vrrp group Foo address 198.51.100.33/24 interface eth3 Disabling a VRRP group ---------------------- You can disable a VRRP group with ``disable`` option: .. code-block:: none set high-availability vrrp group Foo disable A disabled group will be removed from the VRRP process and your router will not participate in VRRP for that VRID. It will disappear from operational mode commands output, rather than enter the backup state. Exclude address --------------- Exclude IP addresses from ``VRRP packets``. This option ``excluded-address`` is used when you want to set IPv4 + IPv6 addresses on the same virtual interface or when used more than 20 IP addresses. .. code-block:: none set high-availability vrrp group Foo excluded-address '203.0.113.254/24' set high-availability vrrp group Foo excluded-address '2001:db8:aa::1/64' set high-availability vrrp group Foo excluded-address '2001:db8:22::1/64' Setting VRRP group priority --------------------------- VRRP priority can be set with ``priority`` option: .. code-block:: none set high-availability vrrp group Foo priority 200 The priority must be an integer number from 1 to 255. Higher priority value increases router's precedence in the master elections. Sync groups ----------- A sync group allows VRRP groups to transition together. .. code-block:: none edit high-availability vrrp set sync-group MAIN member VLAN9 set sync-group MAIN member VLAN20 In the following example, when VLAN9 transitions, VLAN20 will also transition: .. code-block:: none vrrp { group VLAN9 { interface eth0.9 address 10.9.1.1/24 priority 200 vrid 9 } group VLAN20 { interface eth0.20 priority 200 address 10.20.20.1/24 vrid 20 } sync-group MAIN { member VLAN20 member VLAN9 } } .. warning:: All items in a sync group should be similarly configured. If one VRRP group is set to a different preemption delay or priority, it would result in an endless transition loop. Preemption ---------- VRRP can use two modes: preemptive and non-preemptive. In the preemptive mode, if a router with a higher priority fails and then comes back, routers with lower priority will give up their master status. In non-preemptive mode, the newly elected master will keep the master status and the virtual address indefinitely. By default VRRP uses preemption. You can disable it with the "no-preempt" option: .. code-block:: none set high-availability vrrp group Foo no-preempt You can also configure the time interval for preemption with the "preempt-delay" option. For example, to set the higher priority router to take over in 180 seconds, use: .. code-block:: none set high-availability vrrp group Foo preempt-delay 180 Track ----- Track option to track non VRRP interface states. VRRP changes status to ``FAULT`` if one of the track interfaces in state ``down``. .. code-block:: none set high-availability vrrp group Foo track interface eth0 set high-availability vrrp group Foo track interface eth1 Ignore VRRP main interface faults .. code-block:: none set high-availability vrrp group Foo track exclude-vrrp-interface Unicast VRRP ------------ By default VRRP uses multicast packets. If your network does not support multicast for whatever reason, you can make VRRP use unicast communication instead. .. code-block:: none set high-availability vrrp group Foo peer-address 192.0.2.10 set high-availability vrrp group Foo hello-source-address 192.0.2.15 rfc3768-compatibility --------------------- RFC 3768 defines a virtual MAC address to each VRRP virtual router. This virtual router MAC address will be used as the source in all periodic VRRP messages sent by the active node. When the rfc3768-compatibility option is set, a new VRRP interface is created, to which the MAC address and the virtual IP address is automatically assigned. .. code-block:: none set high-availability vrrp group Foo rfc3768-compatibility Verification .. code-block:: none $show interfaces ethernet eth0v10 eth0v10@eth0: mtu 1500 qdisc noqueue state UP group default qlen 1000 link/ether 00:00:5e:00:01:0a brd ff:ff:ff:ff:ff:ff inet 172.25.0.247/16 scope global eth0v10 valid_lft forever preferred_lft forever Scripting --------- VRRP functionality can be extended with scripts. VyOS supports two kinds of scripts: health check scripts and transition scripts. Health check scripts execute custom checks in addition to the master router reachability. Transition scripts are executed when VRRP state changes from master to backup or fault and vice versa and can be used to enable or disable certain services, for example. Health check scripts ^^^^^^^^^^^^^^^^^^^^ This setup will make the VRRP process execute the ``/config/scripts/vrrp-check.sh script`` every 60 seconds, and transition the group to the fault state if it fails (i.e. exits with non-zero status) three times: .. code-block:: none set high-availability vrrp group Foo health-check script /config/scripts/vrrp-check.sh set high-availability vrrp group Foo health-check interval 60 set high-availability vrrp group Foo health-check failure-count 3 Transition scripts ^^^^^^^^^^^^^^^^^^ Transition scripts can help you implement various fixups, such as starting and stopping services, or even modifying the VyOS config on VRRP transition. This setup will make the VRRP process execute the ``/config/scripts/vrrp-fail.sh`` with argument ``Foo`` when VRRP fails, and the ``/config/scripts/vrrp-master.sh`` when the router becomes the master: .. code-block:: none set high-availability vrrp group Foo transition-script backup "/config/scripts/vrrp-fail.sh Foo" set high-availability vrrp group Foo transition-script fault "/config/scripts/vrrp-fail.sh Foo" set high-availability vrrp group Foo transition-script master "/config/scripts/vrrp-master.sh Foo" To know more about scripting, check the :ref:`command-scripting` section. Virtual-server -------------- .. include:: /_include/need_improvement.txt Virtual Server allows to Load-balance traffic destination virtual-address:port between several real servers. Algorithm ^^^^^^^^^ Load-balancing schedule algorithm: * round-robin * weighted-round-robin * least-connection * weighted-least-connection * source-hashing * destination-hashing * locality-based-least-connection .. code-block:: none set high-availability virtual-server 203.0.113.1 algorithm 'least-connection' Forward method ^^^^^^^^^^^^^^ * NAT * direct * tunnel .. code-block:: none set high-availability virtual-server 203.0.113.1 forward-method 'nat' Real server ^^^^^^^^^^^ Real server IP address and port .. code-block:: none set high-availability virtual-server 203.0.113.1 real-server 192.0.2.11 port '80' Example ^^^^^^^ Virtual-server can be configured with VRRP virtual address or without VRRP. In the next example all traffic destined to ``203.0.113.1`` and port ``8280`` protocol TCP is balanced between 2 real servers ``192.0.2.11`` and ``192.0.2.12`` to port ``80`` Real server is auto-excluded if port check with this server fail. .. code-block:: none set interfaces ethernet eth0 address '203.0.113.11/24' set interfaces ethernet eth1 address '192.0.2.1/24' set high-availability vrrp group FOO interface 'eth0' set high-availability vrrp group FOO no-preempt set high-availability vrrp group FOO priority '150' set high-availability vrrp group FOO address '203.0.113.1/24' set high-availability vrrp group FOO vrid '10' set high-availability virtual-server 203.0.113.1 algorithm 'source-hashing' set high-availability virtual-server 203.0.113.1 delay-loop '10' set high-availability virtual-server 203.0.113.1 forward-method 'nat' set high-availability virtual-server 203.0.113.1 persistence-timeout '180' set high-availability virtual-server 203.0.113.1 port '8280' set high-availability virtual-server 203.0.113.1 protocol 'tcp' set high-availability virtual-server 203.0.113.1 real-server 192.0.2.11 port '80' set high-availability virtual-server 203.0.113.1 real-server 192.0.2.12 port '80'