vrrpd is an implementation of VRRPv2 as specified in rfc2338. It run in userspace for linux. In short,
VRRP is a protocol which elects a master server on a LAN and the master answers to a 'virtual ip
address'. If it fails, a backup server takes over the ip address.
A longer answer in the rfc2338 abstract : "This memo defines the Virtual Router Redundancy Protocol
(VRRP). VRRP specifies an election protocol that dynamically assigns responsibility for a virtual router
to one of the VRRP routers on a LAN. The VRRP router controlling the IP address(es) associated with a
virtual router is called the Master, and forwards packets sent to these IP addresses. The election
process provides dynamic fail over in the forwarding responsibility should the Master become unavailable.
This allows any of the virtual router IP addresses on the LAN to be used as the default first hop router
by end-hosts. The advantage gained from using VRRP is a higher availability default path without
requiring configuration of dynamic routing or router discovery protocols on every end-host." Copyright
(C) The Internet Society (1998). All Rights Reserved.
Monitored interface functionality is useful on high availability router or firewall platforms, where
single interface failure can cause asymmetrical routing issues.
Ideally, what is required is a method for a vrrpd process to detect a failure of the 'other' network
interface, and lower it's own VRRP priority below that of the 'backup' vrrpd process. This allows
failover to occur normally.
OPTIONS-h display this short inlined help
-n Don't handle the virtual mac address
-D Go into background mode, daemonize
-iifname
the interface name to run on. More than one interface can be monitored by the one vrrpd process,
a list like "eth1 eth2 eth3 eth4 eth5" is acceptable. Losing link-beat on any of these will cause
the priority of that vrrpd process to be decreased by the specified value, or a default of 100.
Note that as MII calls are used, this implementation is limited to Fast and Gigabit Ethernet
chipsets only - 10Mbps Ethernet cards will not work.
-vvrid
the id of the virtual server [1-255]
-s iqxSwitch the preemption mode (Enabled by default)
-aauth
set the authentification type auth=(none|pw/hexkey|ah/hexkey) hexkey=0x[0-9a-fA-F]+ Password is a
symbolic security, anybody with a sniffer can break it. AH is a bit stronger.
-pprio
Set the priority of this host in the virtual server (dfl: 100)
-fpiddir
specify the directory where the pid file is stored (dfl: /var/run)
-ddelay
Set the advertisement interval (in sec) (dfl: 1) -mifname Interface(s) to monitor for failure.
Use " " for multiple interfaces
-cdelta
Set the delta to decrease priority by (dfl: 50)
ipaddr the ip address(es) of the virtual server