Configuring Layer 3 Redundancy with HSRP

Describing Routing Issues

Default gateway fails

Standby takes over

Identifying the Router Redundancy Process

Virtual Router

Standby takes over

Describing HSRP

An HSRP group consists of the following:

Active router
Standby router
Virtual router
Other routers

HSRP active and standby routers send hello messages to the multicast address 224.0.0.2 using UDP port 1985.

Identifying HSRP Operations

HSRP operation

Describing HSRP States

HSRP States

HSRP State Descriptions

Describing HSRP Configuration Commands

HSRP Configuration Commands

Optimizing HSRP

Describing HSRP Optimization Options

These options can be configured to optimize HSRP:

Standby Priority
Standby Preempt
Message Timers
Interface Tracking

HSRP Standby Priority

HSRP Stanby Preempt

HSRP Stanby Timers

HSRP Tracking

Configuration

interface vlan 10
 ip address 10.0.0.2 255.255.255.0
 standby 1 ip 10.0.0.1
 standby 1 priority 150
 standby 1 preempt
 standby 1 preempt delay minimum 180
 standby 1 track GigabitEthernet 0/1 50
 standby 1 timers msec 200 msec 750

interface vlan 10
 ip address 10.0.0.3 255.255.255.0
 standby 1 ip 10.0.0.1
 standby 1 priority 100
 standby 1 preempt
 standby 1 preempt delay minimum 180
 standby 1 track GigabitEthernet 0/1 50
 standby 1 timers msec 200 msec 750

Describing Load Sharing

Multiple HSRP groups

HSRP Load Balancing

Configuring Layer 3 Redundancy with VRRP and GLBP

Describing Virtual Router Redundancy

RFC 2338

VRRP

VRRP Operation

Configuring VRRP

Configure VRRP

Describing GLBP

GLBP

Active virtual gateway (AVG): Members of a GLBP group elect one gateway to be the AVG for that group. Other group members provide backup for the AVG if the AVG becomes unavailable. The AVG assigns a virtual MAC address to each member of the group.
Active virtual forwarder (AVF): Each gateway assumes responsibility for forwarding packets sent to the virtual MAC address assigned to it by the AVG. These gateways are known as AVFs for their virtual MAC address.
Communication: GLBP members communicate with each other using hello messages sent every 3 seconds to the multicast address 224.0.0.102, User Datagram Protocol (UDP) port 3222.