3Com 4007, Implementation Manual, Page: 408 / 684

408 C
HAPTER
17: V
IRTUAL
R
OUTER
R
EDUNDANCY
P
ROTOCOL
(VRRP)
See Figure 48 for a graphic example of a VRRP topology on two
Switch 4007s. This sample topology directly connects end stations to a
backbone Switch 4007 16-slot chassis. The end stations can
communicate with end stations on LANs that are external to the 16-slot
chassis (in this example, the external LAN is on a Switch 4007 7-slot
chassis). End stations exist on several departmental IP subnetworks, with
the backbone Multilayer Switching Modules acting as the default
gateways for these end stations.
The Multilayer Switching Modules route traffic between locally attached
and externally attached hosts using their respective internal and external
LANs.
To provide router redundancy for traffic flow between locally and
externally attached end stations, this topology requires
two virtual routers
to be configured:
■
LAN1 — the Primary router on the backplane port of BA2, with the
Backup router on the backplane port of BA1.
■
LAN2 — the Primary router on the front panel port of BA2, with the
Backup router on the front panel port of BA1.
To maintain traffic between locally and externally attached end stations in
the event of a router failure of
only one of the Virtual Routers from
Primary to Backup, RIP-2 or OSPF must be enabled.
Figure 48 Sample VRRP Topology with More than One Virtual Router