20 - Implementing HSRP for First Hop Routing

Question 1

What are 3 types of First Hop Redundancy Protocols (FHRP)?

Answer 1

HSRP, VRRP, and GLBP

Question 2

In addition to the minimum single command needed to implement HSRP, what other commands can be used?

Answer 2

* standby ver 2 * standby 1 ip 10.1.1.1 * standby 1 priority 110 * standby 1 name whatever

Question 3

What is the default priority in HSRP?

Answer 3

100

Question 4

In HSRP if the two routers are brought up at the same time who wins the election as active router?

Answer 4

The router with the highest priority

Question 5

What ‘show’ cmd tells you which router is active?

Answer 5

show standby brief’

Question 6

What does ‘standby preempt’ do?

Answer 6

If an HSRP router comes up and finds another HSRP router that is active it checks priority. If it 1) has a higher priority and 2) is configured with ‘standby preempt’ it will take over the active role

Question 7

What are the two versions of HSRP?

Answer 7

version 1 and version 2

Question 8

Do two routers in an HSRP group have to run the same version?

Answer 8

yes.

Question 9

What will happen if two HSRP routers are using two different HSRP versions?

Answer 9

They won’t recognize each other.

Question 10

What are the 6 differences between HSRP version 1 and version 2?

Answer 10

• ver 2 supports IPv6
• ver 2 supports faster Hello timer
• ver 2 supports up to 4095 group numbers
• ver 2 configures its vmac address differently
• ver 2 uses different multicast address
• ver 2 supports unique identifier for each HSRP router

Question 11

What is the difference between HSRP ver 1 vmac and ver 2 vmac?

Answer 11

ver 1 vmac the last two hex digits are variable, ver 2 the last 3 hex digits are variable

Question 12

What version of HSRP uses a vmac address of 0000.0C07.Acxx ?

Answer 12

version 1

Question 13

What version of HSRP uses a vmac address of 0000.0C9F.Fxxx ?

Answer 13

version 2

Question 14

For 2 routers in an HSRP group, what config parameters must match?

Answer 14

• version number
• same standby group #
• same virtual IP
• virtual IP must be in same subnet as IP address
• same VLAN

Question 15

In addition to checking the parameters that must match what other troubleshooting steps should you do?

Answer 15

• make sure no ACL is filtering UDP port 1985
• ver 1 sends to 224.0.0.2
• ver 2 sends to 224.0.0.102

Question 16

What would happen if the 2 HSRP routers had different virtual Ips configured?

Answer 16

* HSRP would not go active * virtual IP changes based on whichever router is active

Question 17

What would happen if the 2 HSRP routers were using different versions?

Answer 17

They would become active but a duplicate IP address would be detected

Question 18

What would happen if the 2 HSRP routers had a group mismatch?

Answer 18

They would become active but a duplicate IP address would be detected

Question 19

HSRP, at a minimum, needs only a single command to work. What is that command?

Answer 19

standby 1 ip 172.21.2.1

Question 20

What 7 items are shown by ‘show standby brief”

Answer 20

• Interface
• Group
• Priority
• State
• Active
• Standby
• Virtual IP

Question 21

What are HSRP default Hello and Hold timers?

Answer 21

• Hello is 3 sec
• Hold is 10 sec

Question 22

What are the rules that determine which HSRP point is active?

Answer 22

• if the local router doesn’t see any other HSRP routers it becomes active
• Whichever router has the highest priority wins the election
• If a router comes up, sees and already active HSRP even if the other router has higher priority it will go into standy unless….
  
  • the local router is configured to Preempt

Question 23

What ‘show’ command should allow you to back-engineer the HSRP configuration?

Answer 23

show standby

Question 24

What commands are used to track the line protocol of an interface?

Answer 24

• track 1 interface Serial0/0/0 line-protocol

Then in HSRP config add:

• int gig0/0
  
  • standby 1 track 1 decrement 50

Question 25

What are the 6 states that HSRP can be in?

Answer 25

• Init - first starting
• Learn - no virtual IP address, no Hellos
• Listen - knows virtual IP, no Hellos but listening for them
• Speak - Has virtual IP, participates in election, is sending Hellos
• Standby - Not the active HSRP point
• Active - Is the Active HSRP router