EIGRP

Question 1

Multicast Address

Answer 1

224.0.0.10

Question 2

Hello Packet Timer

Answer 2

Every 5 seconds

Question 3

Dead Time Interval

Answer 3

Every 15 Seconds

Question 4

EIGRP Metric Calculation pt1

Answer 4

256 ( [k1Bandwidth] + [k3Delay])

Question 5

EIGRP Metric Calculation pt2 DELAY

Answer 5

Delay is the sum of all the delays of the link along the path.
Delay = [Sum of Total Delay/10]*256

Question 6

EIGRP Metric Calculation pt3 BANDWIDTH

Answer 6

Bandwidth is the lowest bandwidth of the links along the path.
BW = (10^7 /lowest bandwidth in kbps)*256

Question 7

What is the Feasible distance?

Answer 7

This is the total cost from the local router to the destination.
FD = AD + cost between local router and next hop

Question 8

Advertise Distance

Answer 8

Cost of next- hop router to destination

Question 9

How does EIGRP calculate the second best route?

Answer 9

The route has to satisfy the feasibility condition.

Question 10

What is the successor?

Answer 10

Best route to the destination

Question 11

Feasible successor?

Answer 11

Backup path

Question 12

Feasibility condition

Answer 12

The FD of the current successor router > AD of the feasible successor.

Question 13

What will EIGRP do if it does not have a feasible successor for a route and the successor route goes down?

Answer 13

It will send out query messages to find another successor and possibly feasible successor

Question 14

What is stuck in Active

Answer 14

• If a successor path is lost and no feasible successor is identified, the router sends out queries on all interfaces in an attempt to identify an alternate path.
• No successor can be chosen until the router receive replies from all queries.
• If a reply is missing for 3 minutes, the router becomes stuck in active (SIA) [older version ios]
• In that case it resets the neighbor relationship with the neighbor that did not reply.
• with newer version ios, the upstream routers will send out a SIA Query message after 90 seconds. if they get a reply, the neighbor-ship will not be broken.

What is Keith Baker’s example

Question 15

What is Stub Routing used for?

Answer 15

To limit queries. Improves network stability and reduces resource utilization.

Question 16

How can a route be used in unequal cost load balancing?

Answer 16

by using the variance command. The cost of the successor multiply by the variance must be greater than the cost of the other routes to be used for load balancing.

Question 17

Tables

Answer 17

Neighbor Table | Topology Table | Routing Table