Key Concepts - 3Com corebuilder 3500 Implementation Manual

318 C 12: V
HAPTER IRTUAL

Key Concepts

R R P
OUTER EDUNDANCY ROTOCOL
Figure 62 Simple VRRP Configuration
Router A
PC
Router B
In the example shown in Figure 62, Router A is the default gateway for
the workstation named PC, which provides access to the Wide Area
Network (WAN) and to the device named Server. Assume that no router
discovery protocols have been configured and that the default gateway is
static.
If the workstation loses its connection to Router A, the workstation loses
all remote connectivity because its default gateway is no longer available.
However, if VRRP is enabled in this same scenario, Router B detects the
loss of connectivity to Router A, and Router B assumes all forwarding
responsibilities on behalf of Router A. This transfer of forwarding
responsibilities allows the workstation to have continued access across
the WAN to the server.
This section contains some VRRP definitions that you should know before
reading further.
VRRP router — A router running the VRRP protocol. A VRRP router
can:
Act as a Master router with actual addresses on a interface
Act simultaneously as a Backup for other routers with additional
virtual router mappings and priorities for those routers
Virtual router — A logical entity, managed by VRRP, that acts as the
default router for hosts on a shared LAN. The virtual router has a
unique identifier called the Virtual Router Identifier (VRID), and has a
set of associated IP addresses across the LAN.
(VRRP)
WAN
Router C
Server
Router D