HSRP protocol/VRRP protocol

Hot backup routing protocol
HSRP protocol is a Cisco proprietary protocol, VRRP is an open protocol, both are hot backup routing protocols

1 HSRP group number: 1-255

2 The ip of the virtual router is called the virtual IP address VIP

3 Members of HSRP group

1. Virtual router
2. Active router
3. Backup router
4. Other routers

4 HSRP priority: 1-255
defaults to 100, the higher the number, the higher the priority

5 HSRP group members communicate by sending hello packets regularly. The
default persistence time is 10 seconds every 3 seconds.

6
Preemptive role: When the other party is not detected, or the other party's priority is lower than itself, the active route is immediately preempted

7 Configure the tracking track to track the status of the external network port. If the external network is down, the priority will be lowered automatically

command

Router 1 (R1)

int f0/0

standby 1 ip 192.168.1.252 (define the group number as 1 and VIP as 192.168.1.252)
standby 1 priority 200 (define priority)
standby 1 preempt (enable preemption)
standby 1 track f0/1 10 (track the external network port, if it is down If dropped, the priority will be reduced by 10)
exit

Router 2 (R2)

int f0/0

standby 1 ip 192.168.1.252 (define group number 1 and VIP as 192.168.1.252)
standby 1 priority 190 (define priority)
standby 1 preempt (enable preemption)

exit

View HSRP status
show standby br
show standby