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Alteon OS Application Guide
Chapter 13: High Availability
22542C4911, January 2007
There is no requirement for any VRRP router to be the IP address owner. Most VRRP installa-
tions choose not to implement an IP address owner. For the purposes of this chapter, VRRP
routers that are not the IP address owner are called renters.
Master and Backup Virtual Router
Within each virtual router, one VRRP router is selected to be the virtual router master. See
“Selecting the Master VRRP Router” on page 226 for an explanation of the selection process.
NOTE – If the IP address owner is available, it will always become the virtual router master.
The virtual router master forwards packets sent to the virtual router. It also responds to Address
Resolution Protocol (ARP) requests sent to the virtual router's IP address. Finally, the virtual
router master sends out periodic advertisements to let other VRRP routers know it is alive and
its priority.
Within a virtual router, the VRRP routers not selected to be the master are known as virtual
router backups. Should the virtual router master fail, one of the virtual router backups becomes
the master and assumes its responsibilities.
Virtual Interface Router
At Layer 3, a Virtual Interface Router (VIR) allows two VRRP routers to share an IP interface
across the routers. VIRs provide a single Destination IP (DIP) for upstream routers to reach
various destination networks, and provide a virtual default Gateway.
NOTE – Every VIR must be assigned to an IP interface, and every IP interface must be assigned
to a VLAN. If no port in a VLAN has link up, the IP interface of that VLAN is down, and if the
IP interface of a VIR is down, that VIR goes into INIT state.