HSRP Configuration: Explained

HSRP is a protocol that helps to achieve the failover. With the help of HSRP, we can configure active and standby routers and that goal is achieved with the help of a virtual IP. When active goes down, the standby router comes to the rescue. Let us understand the Cisco HSRP Configuration.

Given below is the topology that will help us understand the HSRP configuration.

R1 is configured with 192.168.1.1 and R2 is configured with 192.168.1.2.  

192.168.1.254 is the virtual IP. 

R1(config)#interface GigabitEthernet0/0/0 

R1(config-if)#ip address 192.168.1.1 255.255.255.0 

R1(config-if)#no shutdown  

R1(config-if)#standby 1 ip 192.168.1.254 

R1(config-if)#exit 

%HSRP-6-STATECHANGE: GigabitEthernet0/0/0 Grp 1 state Standby -> Standby 

This message will pop up. 
R1 is now a standby router. 
Why so? 

Since we have not configured any priority, and the default priority is 100. So the router with a lesser IP Address becomes the standby while the router with a Higher IP address becomes an Active router. 

Let's configure R2.

R2(config)#interface GigabitEthernet0/0/1 

R2(config-if)#ip address 192.168.1.2 255.255.255.0 

R2(config-if)#no shutdown 

R2(config-if)#standby 1 ip 192.168.1.254 

R2(config-if)#exit 

%HSRP-6-STATECHANGE: GigabitEthernet0/0/1 Grp 1 state Standby -> Active 

R2 becomes an active router since priority is 100 which is default but it has a Higher IP Address. 

Verification

R1#show standby 

GigabitEthernet0/0/0 – Group 1 

State is Standby 

8 state changes, last state change 00:18:38 

Virtual IP address is 192.168.1.254 

Active virtual MAC address is 0000.0C07.AC01 

Local virtual MAC address is 0000.0C07.AC01 (v1 default) 

Hello time 3 sec, hold time 10 sec 

Next hello sent in 1.285 secs 

Preemption disabled 

Active router is 192.168.1.2 

Standby router is local 

Priority 100 (default 100) 

Group name is hsrp-Gig0/0/0-1 (default) 

R2#show standby  

GigabitEthernet0/0/1 – Group 1 

State is Active 

5 state changes, last state change 00:05:14 

Virtual IP address is 192.168.1.254 

Active virtual MAC address is 0000.0C07.AC01 

Local virtual MAC address is 0000.0C07.AC01 (v1 default) 

Hello time 3 sec, hold time 10 sec 

Next hello sent in 0 secs 

Preemption disabled 

Active router is local 

Standby router is 192.168.1.1 

Priority 100 (default 100) 

Group name is hsrp-Gig0/0/1-1 (default) 

Let us configure the priority value and make R1 an Active Router. 

R1(config)#interface GigabitEthernet0/0/0 

R1(config-if)#ip address 192.168.1.1 255.255.255.0 

R1(config-if)#no shutdown  

R1(config-if)# standby 1 ip 192.168.1.254 

R1(config-if)# standby 1 priority 110 

R1(config-if)# standby 1 preempt 

%HSRP-6-STATECHANGE: GigabitEthernet0/0/0 Grp 1 state Speak -> Standby 

%HSRP-6-STATECHANGE: GigabitEthernet0/0/0 Grp 1 state Standby -> Active 

R1 goes from standby to Active since priority is set to 110 which is higher than default priority configured on R2 i.e. 100 

R2(config)#interface GigabitEthernet0/0/1 R2(config-if)#ip address 192.168.1.2 255.255.255.0 R2(config-if)#no shutdown R2(config-if)#standby 1 ip 192.168.1.254 R2(config-if)# standby 1 priority 100 

%HSRP-6-STATECHANGE: GigabitEthernet0/0/1 Grp 1 state Speak -> Standby

The “preempt” here in HSRP is used to specify that a router with a higher priority should automatically take back the role of the active (primary) router when it becomes available again after a failure. 

Verification

R1#show standby  

GigabitEthernet0/0/0 – Group 1 

State is Active 

5 state changes, last state change 00:02:11 

Virtual IP address is 192.168.1.254 

Active virtual MAC address is 0000.0C07.AC01 

Local virtual MAC address is 0000.0C07.AC01 (v1 default) 

Hello time 3 sec, hold time 10 sec 

Next hello sent in 1.966 secs 

Preemption enabled 

Active router is local 

Standby router is 192.168.1.2 

Priority 110 (configured 110) 

Group name is hsrp-Gig0/0/0-1 (default)

R2#show standby  

GigabitEthernet0/0/1 – Group 1 

State is Standby 

3 state changes, last state change 00:02:29 

Virtual IP address is 192.168.1.254 

Active virtual MAC address is 0000.0C07.AC01 

Local virtual MAC address is 0000.0C07.AC01 (v1 default) 

Hello time 3 sec, hold time 10 sec 

Next hello sent in 0.992 secs 

Preemption disabled 

Active router is 192.168.1.1 

Standby router is localbl 

Priority 100 (default 100) 

Group name is hsrp-Gig0/0/1-1 (default)