Nortel Networks 42C4911 Manual de usuario descargar pdf (Pagina 225)

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.

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Nortel Networks 42C4911 Manual de usuario Pagina 225