18-1
Chapter 18: 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). VRRP allows
you to specify the interface of one of the routers participating in the virtual group as
the address for the master virtual router, or to configure an arbitrary address for the
virtual master 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. These
examples use the address of one of the participating routers as the master router.
When the virtual router IP address is not a real address, the master router is
selected based on priority. When the priority is the same on several competing
routers, then the router with the highest IP address is selected as the master.
• 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
Summary of Contents for 8926EM
Page 6: ...ii ...
Page 34: ...Getting Started ...
Page 44: ...Introduction 1 10 1 ...
Page 62: ...Initial Configuration 2 18 2 ...
Page 64: ...Switch Management ...
Page 76: ...Configuring the Switch 3 12 3 ...
Page 118: ...Basic Management Tasks 4 42 4 ...
Page 164: ...User Authentication 6 28 6 ...
Page 176: ...Access Control Lists 7 12 7 ...
Page 284: ...Quality of Service 14 8 14 ...
Page 294: ...Multicast Filtering 15 10 15 ...
Page 300: ...Domain Name Service 16 6 16 ...
Page 310: ...Dynamic Host Configuration Protocol 17 10 17 ...
Page 320: ...Configuring Router Redundancy 18 10 18 ...
Page 344: ...IP Routing 19 24 19 ...
Page 356: ...Unicast Routing 20 12 20 Web Click Routing Protocol RIP Statistics Figure 20 5 RIP Statistics ...
Page 386: ...Unicast Routing 20 42 20 ...
Page 388: ...Command Line Interface ...
Page 400: ...Overview of the Command Line Interface 21 12 21 ...
Page 466: ...SNMP Commands 24 16 24 ...
Page 520: ...Access Control List Commands 26 18 26 ...
Page 546: ...Rate Limit Commands 30 2 30 ...
Page 612: ...VLAN Commands 34 24 34 ...
Page 626: ...Class of Service Commands 35 14 35 ...
Page 670: ...DHCP Commands 39 16 39 ...
Page 716: ...IP Interface Commands 41 36 41 ...
Page 768: ...IP Routing Commands 42 52 42 ...
Page 770: ...Appendices ...
Page 791: ......