Review - Chapter 6

Question 1

First-Hop Redundancy

Answer 1

A set of routers/Layer 3 switches work together to present the illusion of a single virtual router to hosts on the LAN by sharing an IP and MAC address

Question 2

Hot Standby Router Protocol (HSRP)

Answer 2

Active and Standby routers send hello messages to multicast address using UDP port 1985 which are used to communicate between routers in the HSRP group

Question 3

HSRP Multicast Addresses

Answer 3

• 224.0.0.2 (V1)

* 224.0.0.102 / FF02::66 (V2)

Question 4

Active Router

Answer 4

• Forwards data and transmits hello messages for the Virtual Router
• Highest priority/IP address

Question 5

Standby Router

Answer 5

• Primary backup for the Active Router

* Second highest priority/IP address

Question 6

Standby Group

Answer 6

A set of routers that emulate a virtual router (255 V1, 4095 V2)

Question 7

HSRP Hello Interval

Answer 7

Interval between hellos (3s)

Question 8

HSRP Hold Interval

Answer 8

Amount of time a hello is valid (10s)

Question 9

HSRP States

Answer 9

• Initial
• Learn (Rare)
• Listen (Duration = Hold time)
• Speak
• Standby
• Active

Question 10

Virtual Router Redundancy Protocol (VRRP)

Answer 10

• Allows a group of routers to form a single virtual router
• Priority can be 0-255
• Preempt is enabled by default

Question 11

VRRP Advertisements

Answer 11

• Sent to multicast 244.0.0.18 protocol 112
• Default interval 1s
• Default hold time 3s

Question 12

VRRP Dynamic Failover

Answer 12

Three timers:
• advertisement (1s)
• master down (3x Ad.Int + skew)
• skew time (256 - priority) / 256

Question 13

Gateway Load Balancing Protocol (GLBP)

Answer 13

• Provides redundancy

* Allows a group of routers to share the load of the default gateway on a LAN (different ARP reply to different hosts)

Question 14

GLBP Operational Modes

Answer 14

• Weighted
• Host-dependent
• Round-robin (default)