Configuring Router Redundancy
18-2
18
• Several virtual master routers configured for mutual backup and load sharing.
Load sharing can be accomplished by assigning a subset of addresses to different
host address pools using the DHCP server. (See 'Configuring Address Pools" on
page 17-4.)
Virtual Router Redundancy Protocol
Virtual Router Redundancy Protocol (VRRP) allows you to configure a group of
routers as a single virtual router. The virtual router group is configured with a single
virtual IP address that can be used as the default gateway for host devices on the
attached network.
Configuring VRRP Groups
To configure VRRP, select an interface on each router in the group that will
participate in the protocol as the master router or a backup router. To select a
specific device as the master router, set the address of this interface as the virtual
router address for the group. Now set the same virtual address and a priority on the
backup routers, and configure an authentication string. You can also enable the
preempt feature which allows a router to take over as the master router when it
comes on line if it has a higher priority than the currently active master router.
Command Usage
Address Assignment –
• To designate a specific router as the VRRP master, the IP address assigned to the
virtual router must already be configured on the router that will become the Owner
of the group address. In other words, the IP address for the virtual router exists on
one, and only one, router in the virtual router group, and the network mask for the
virtual router address is derived from the Owner. The Owner will also assume the
role of the Master virtual router in the group.
• If a virtual address is assigned to the group which does not exist on any of the
group members, then the master router is selected based on priority. In cases
Router 1
VRID 23 (Master)
IP(R1) = 192.168.1.3
IP(VR23) = 192.168.1.3
VR Priority = 255
VRID 25 (Backup)
IP(R1) = 192.168.1.3
IP(VR25) = 192.168.1.5
VR Priority = 100
Router 2
VRID 23 (Backup)
IP(R1) = 192.168.1.5
IP(VR23) = 192.168.1.3
VR Priority = 100
VRID 25 (Master)
IP(R1) = 192.168.1.5
IP(VR25) = 192.168.1.5
VR Priority = 255
Hosts (192.168.1.10-99)
Hosts (192.168.1.100-250)
LAN Segment A
LAN Segment B
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: ......