C
ONFIGURING
R
OUTER
R
EDUNDANCY
3-225
Configuring Router Redundancy
Router redundancy protocols use a virtual IP address to support a primary
router and multiple backup routers. The backup routers can be configured
to take over the workload if the master router fails, or can also be
configured to share the traffic load. The primary goal of router redundancy
is to allow a host device which has been configured with a fixed gateway to
maintain network connectivity in case the primary gateway goes down.
This switch supports both the Virtual Router Redundancy Protocol
(VRRP) and Hot Standby Router Protocol (HSRP). These protocols are
very similar. The primary difference is that VRRP requires you to specify
the interface of one of the routers participating in the virtual group as the
address for the master virtual router, while HSRP requires you to configure
an arbitrary address for the virtual master router. Both protocols then
select the backup routers based on the specified virtual router priority.
HSRP also includes the ability to dynamically modify the virtual router
priority based on the operational state of other interfaces on the router.
Router redundancy can be set up in any of the following configurations.
The following examples show configuration settings for VRRP. The only
difference for HSRP is that the virtual router IP address is never a real
address, and the master router is selected based on priority only.
•
A master virtual router with one or more backup routers.
Master Router
Backup Router
Virtual Router (VR23)
VRIP = 192.168.1.3
VRID 23
IP(R1) = 192.168.1.3
IP(VR23) = 192.168.1.3
VR Priority = 255
VRID 23
IP(R2) = 192.168.1.5
VRIP(VR23) = 192.168.1.3
VR Priority = 100
Summary of Contents for 8612XL3
Page 2: ......
Page 26: ...CONTENTS xxvi ...
Page 40: ...INTRODUCTION 1 14 ...
Page 69: ...BASIC CONFIGURATION 3 15 ...
Page 175: ...PORT CONFIGURATION 3 121 ...
Page 337: ...IP ROUTING 3 283 Web Click Routing Protocol RIP Statistics ...
Page 379: ...MULTICAST ROUTING 3 325 Command Usage ...
Page 396: ...CONFIGURING THE SWITCH 3 342 ...
Page 582: ...COMMAND LINE INTERFACE 4 186 ...
Page 806: ... 224 Command Mode Privileged Exec Example Console clear vrrp 1 interface 1 counters Console ...
Page 826: ... 6 ...
Page 828: ...TROUBLESHOOTING B 2 ...
Page 838: ...GLOSSARY Glossary 10 ...
Page 845: ......