HSRP (Hot Standby Routing Protocol) defines an active-standby router configuration using virtual IP and MAC addresses to provide default gateway redundancy. The router with the highest priority value becomes the active router and sends periodic hello messages to the standby router. The show standby command can be used to verify the HSRP state and priority values of routers.

1. Understanding Layer 3 Redundancy
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HOT STANDBY ROUTING
PROTOCOL
PRESENTED BY :
A.MOHAMED JAFAR DEEN

2. HSRP
 HSRP defines a group of routers -- one active and one
standby.
 Virtual IP and MAC addresses are shared between the two
routers.
 To verify HSRP state, use the show standby command.
 HSRP is Cisco proprietary,
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3. GROUP NUMBER AND PRIORITY
VALUE
GROUP NO VERSION 1 : 0 – 255
GROUR NO VERSION 2 : 4096
PRIORITY VALUE : 1-255

4. MULTICAST ADDRESS
VERSION 1 : 224.0.0.2
VERSION 2 : 224.0.0.102

5. HSRP (Cont.)
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 Active router:
 Active router send hello packet for every 3 sec to standby
router
 Standby Router:
Listens for periodic hello messages
Cisco Confidential

6. Default Gateway Redundancy
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7. Configuring HSRP
 Routers A and B are configured with priorities of 110 and 90,
respectively. The configuration of Router A is displayed. A
similar configuration is required on Router B.
• Now router A is in active state and B in standby state
based on highest priority value.
RouterA(config)# interface GigabitEthernet0/0
RouterA(config-if)# ip address 10.1.10.2 255.255.255.0
RouterA(config-if)# standby 1 ip 10.1.10.1
RouterA(config-if)# standby 1 priority 110
RouterA(config-if)# standby 1 preempt
RouterA
Priority
110
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Router B
Priority
90
HSRP
Group 1

8. HSRP Verification
Use the show standby command to verify the HSRP state.
RouterA# show standby
GigabitEthernet0/0 - Group 1 (version 2)
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State is Active
2 state changes, last state change 00:00:18
Virtual IP address is 10.1.10.1
Active virtual MAC address is 0000.0C9F.F001
Local virtual MAC address is 0000.0C9F.F001 (v2 default)
Hello time 3 sec, hold time 10 sec
Next hello sent in 2.278 secs
Preemption enabled
Active router is local
Standby router is 10.1.10.3, priority 90 (expires in 9 sec)
Priority 110 (configured 110)
Group name is hsrp-Gig0/0-1 (default)

9. HSRP Verification (Cont.)
The show standby brief command displays a summary
of the HSRP configurations.
RouterA# show standby brief
P indicates configured to preempt.
|
Interface Grp Pri P State Active Standby
Gig0/0 1 110 P Active local 10.1.10.3
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Virtual IP
10.1.10.1

10. HSRP Interface Tracking
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11. ADVANTAGE OF HSRP:
• USED FOR BACKUP PROCESS
• NO NEED TO CHANGE DEFAULT
GATEWAY EVERY TIME
• NO FAULT TOLERRANCE