Infrastructure Services: DNS, DHCP, NTP, HSRP

This chapter is from the book

CCNA Routing and Switching 200-125 Exam Cram, 5th Edition

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This chapter is from the book

This chapter is from the book 

CCNA Routing and Switching 200-125 Exam Cram, 5th Edition

Learn More Buy

Topic: Configure, verify, and troubleshoot basic HSRP

The Hot Standby Router Protocol (HSRP) allows multiple default gateways to respond to clients and permit them access off of their LAN segment. This technology was invented by Cisco Systems and is known as a First Hop Redundancy Protocol (FHRP).

HSRP has each router (or even more than two devices) present a virtual IP address to the LAN segment. The active router can respond to this virtual IP address and forward traffic. The device that forwards traffic is called the active router, and the others in the group are called standby routers.

The HSRP routers communicate with each other every three seconds by default to ensure they are up. There is a dead timer of ten seconds. Example 14.13 demonstrates the HSRP configuration on two routers connected to a LAN segment.

EXAMPLE 14.13 Configuring HSRP

R1#
R1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#interface gi0/1
R1(config-if)#standby 10 ip 10.10.10.100
R1(config-if)#end
R1#

R2#
R2#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#interface gi0/1
R2(config-if)#standby 10 ip 10.10.10.100
R2(config-if)#end
R2#

Verification is also simple. Example 14.14 demonstrates the use of the show standby command on R1.

EXAMPLE 14.14 Verifying HSRP

R1#
R1#show standby
GigabitEthernet0/1 - Group 10
  State is Active
    2 state changes, last state change 00:02:03
  Virtual IP address is 10.10.10.100
  Active virtual MAC address is 0000.0c07.ac0a
    Local virtual MAC address is 0000.0c07.ac0a (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 0.304 secs
  Preemption disabled
  Active router is local
  Standby router is 10.10.10.2, priority 100 (expires in 9.552 sec)
  Priority 100 (default 100)
  Group name is "hsrp-Gi0/1-10" (default)
R1#

Notice that R1 is the active router. The virtual IP address is our assignment of 10.10.10.100. The actual IP addresses on R1 and R2 are 10.10.10.1 and 10.10.10.2, respectively. Notice the default priority is in place of 100. The greater the priority number, the higher the priority is. This directly controls the active router assignment. Example 14.15 demonstrates setting preemption (disabled by default) and setting the priority to immediately win the active role.

EXAMPLE 14.15 Setting Preemption and Adjusting HSRP Priority

R2#
R2#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#interface gi0/1
R2(config-if)#standby 10 preempt
R2(config-if)#standby 10 priority 120
R2(config-if)#end
R2#
*%HSRP-5-STATECHANGE: GigabitEthernet0/1 Grp 10 state Standby -> Active
R2#
R2#show standby
GigabitEthernet0/1 - Group 10
  State is Active
    2 state changes, last state change 00:00:10
  Virtual IP address is 10.10.10.100
  Active virtual MAC address is 0000.0c07.ac0a
    Local virtual MAC address is 0000.0c07.ac0a (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 0.640 secs
  Preemption enabled
  Active router is local
  Standby router is 10.10.10.1, priority 100 (expires in 9.552 sec)
  Priority 120 (configured 120)
  Group name is "hsrp-Gi0/1-10" (default)
R2#

CramQuiz

1. What does FHRP stand for?

• A. First Hop Redundancy Protocol

• B. First HSRP Router Protocol

• C. First Hop Routing Protocol

• D. Final Hop Routing Protocol

2. What command permits the verification of your HSRP configuration?

• A. show standby

• B. show router hsrp

• C. show hsrp

• D. show fhrp hsrp

CramQuiz Answers

1. A is correct. HSRP is an example of a First Hop Redundancy Protocol.

2. A is correct. Use show standby for the HSRP verification.