HSRP

Question 1

FHRP

Answer 1

First Hop Redundancy Protocols:
Use a Virtual IP (VIP) & MAC address to allow for automated gateway failover

The hosts use the VIP as their default gateway address

If a physical gateway fails, another gateway will take over

Question 2

FHRP Protocols

Answer 2

HSRP (Hot Standby Router Protocol)
Cisco proprietary
Deployed in active/standby pair

VRRP (Virtual Router Redundancy Protocol)
Open standard
Deployed in active/standby pair. Very similar to HSRP

GLBP (Gateway Load Balancing Protocol)
Cisco proprietary
Supports active/active load balancing across multiple routers

Question 3

HSRP

Answer 3

Hot Standby Router Protocol:
Uses a VIP & MAC address to allow for automated gateway failover

Hosts use the VIP as their default gateway

If the active gateway fails, the standby takes over

Question 4

HSRP Operations

Answer 4

Both routers have a physical IP & MAC on their HSRP interface
(Unique addresses are used on both routers)

They both also have the VIP & MAC configured on the interface
(Same addresses used on both routers)

When they come online, one is elected active, other standby

Active router owns the VIP & MAC & response to ARP requests

Routers send hello messages to each over their HSRP interface

If the standby stops receiving hellos from the active:

• It transitions to be the active router
• Takes ownership of VIP & MAC & responds to ARP requests

Question 5

Command: Configure HSRP with a VIP of 10.10.10.1

Answer 5

R1:
interface g0/1
ip address 10.10.10.2 255.255.255.0
no shutdown
standby 1 ip 10.10.10.1

R2:
interface g0/1
ip address 10.10.10.3 255.255.255.0
no shutdown
standby 1 ip 10.10.10.1

Question 6

Command: View HSRP Info

Answer 6

show standby

Question 7

HSRP Priority

Answer 7

You can choose the active router by setting priority

Highest priority will be preferred active
Higher priority = higher priority value

If they tie, highest IP wins

100 is default

Question 8

HSRP Pre-Emption

Answer 8

If pre-emption is enabled:
When a higher priority router comes back online after a failure, it will transition back to active

If pre-emption is disabled:
Lower priority router remains active when the failed router comes back online

Question 9

Command: Configure HSRP Priority & Pre-Emption on Routers 1 & 2

Answer 9

R1:

Interface g0/1
Ip address 10.10.10.2 255.255.255.0
No shutdown
Standby 1 ip 10.10.10.1
Standby 1 priority 110
Standby 1 preempt

R2:

Interface g0/1
Ip address 10.10.10.3 255.255.255.0
No shutdown
Standby 1 ip 10.10.10.1
Standby 1 priority 90

Question 10

HSRP Version & Version Configuration

Answer 10

Version 2 introduced minor improvements
Default is version 1

Both routers must run the same version

Configuration:
Standby version 2