Ch 9

Question 1

What is the Feasibility Condition?

Answer 1

If a non-successor route’s Reported Distance is less than the Feasible Distance then the route is a Feasible Successor Route

Question 2

What is the Feasible Distance?

Answer 2

The local routers Composite Metric of the best route to reach a subnet - as calculated by the LOCAL ROUTER.

Question 3

What is the Reported Distance?

Answer 3

The next-hop router’s best Composite Metric for the same subnet.

Question 4

Successor

Answer 4

The route with the best metric, or best Feasible Distance. ‘show ip route’ shows the successor routes.

Question 5

What is a Feasible Successor?

Answer 5

A route who’s Reported Distance is less than the local router’s Feasible Distance, if the best route fails EIGRP switches to the Feasible Successor.

Question 6

What does DUAL stand for?

Answer 6

Diffusing Update Algorithm.

Question 7

If a successor route fails what does EIGRP do?

Answer 7

Switches over to the Feasible Successor route, if no Feasible Successor route then DUAL takes over to find a new route.

Question 8

What does DUAL do?

Answer 8

1.) The local router sends EIGRP QUERY messages to its remaining neighbors looking for a route 2.) the neighbor replys with an EIGRP REPLY message confirming a viable route 3.) The route is then entered in the local routers table.

Question 9

What 3 steps does EIGRP do when first joining the network?

Answer 9

1.) Neighbor Discovery 2.) Topology Exchange 3.) Chooses Routes

Question 10

What type of messages are used to discover neighbors?

Answer 10

Hello Messages

Question 11

What type of messages are used to exchange topology?

Answer 11

EIGRP Update Messages

Question 12

What address are EIGRP Hello messages sent to ?

Answer 12

224.0.0.10

Question 13

What address are EIGRP Update Messages sent to ?

Answer 13

The Unicast address of the neighboring router. If multiple neighbors are on the subnet then to 224.0.0.10

Question 14

What protocol does EIGRP use?

Answer 14

Reliable Transport Protocol (RTP)

Question 15

What advantage does RTP have?

Answer 15

provides mechanism to resend any messages that were not received

Question 16

What is the default Hello interval?

Answer 16

5 seconds

Question 17

What is the Hold Interval

Answer 17

The amount of time a router will wait to hear a Hello from its neighbor before declaring it down.

Question 18

What is the default Hold Interval

Answer 18

3 times the Hello time or 15 seconds.

Question 19

How does EIGRP notify its neighbors of a topology change?

Answer 19

EIGRP Partial Update

Question 20

What are the checks that EIGRP performs to determine if it can be a neighbor?

Answer 20

• passes authentication * Same Autonomous System number * Source IP address used by the neighbor to send Hello is on same subnet * EIGRP K-values must match

Question 21

What is the formula EIGRP uses to calculate the Composite Metric?

Answer 21

Metric = ((10^7 / least-bandwidth) + cumulative delay) * 256