Nortel Networks WEB OS 212777 - Manual (Page 249)

Web OS 10.0 Application Guide
Chapter 11: High Availability n 249
212777-A, February 2002
Virtual Router MAC Address
The VRID is used to build the virtual router MAC Address. The five highest-order octets of the
virtual router MAC Address are the standard MAC prefix (00-00-5E-00-01) defined in RFC
2338. The VRID is used to form the lowest-order octet.
Owners and Renters
Only one of the VRRP routers in a virtual interface router may be configured as the IP address
owner. This router has the virtual interface router’s IP address as its real interface address. This
router responds to packets addressed to the virtual interface router’s IP address for ICMP
pings, TCP connections, and so on.
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 251 for an explanation of the selection process.
N OTE – 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 interface router. It also responds to
Address Resolution Protocol (ARP) requests sent to the virtual interface 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.