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Configuring Router Redundancy
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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 the Virtual Router Redundancy Protocol (VRRP). This protocol
requires you to specify the interface of one of the routers participating in the virtual
group as the address for the master virtual router. VRRP then selects the backup
routers based on the specified virtual router priority. Router redundancy can be set
up in any of the following configurations.
• A master virtual router with one or more backup routers.
• Several virtual master routers using the same set of 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
Master Router
VRID 23
IP(R1) = 192.168.1.3
IP(VR23) = 192.168.1.3
VR Priority = 255
Master Router
VRID 25
IP(R2) = 192.168.2.17
IP(VR25) = 192.168.2.17
VR Priority = 255
Backup Router
VRID 23
IP(R3) = 192.168.1.4
IP(VR23) = 192.168.1.3
VR Priority = 100
VRID 25
IP(R3) = 192.168.2.18
IP(VR23) = 192.168.2.17
VR Priority = 100