Chap 7 - EIGRP

Question 1

What makes EIGRP different from other Distance Vector protocols?

Answer 1

EIGRP maintains a topology table.

Question 2

What 4 things does each entry in the topology table contain?

Answer 2

• Network Prefix
• EIGRP neighbors advertising that prefix
• Metrics from each neighbor (Reported Distance, Hop Count)
• Values used in calculating the metric (bandwidth, delay, load, reliability, MTU)

Question 3

In the Topology Table what state is a route in when it is stable?

Answer 3

Passive

Question 4

In the Topology Table what state is a route in when it is computing a new path?

Answer 4

Active

Question 5

What protocol port does EIGRP use?

Answer 5

88

Question 6

What multicast address does EIGRP use?

Answer 6

224.0.0.10

Question 7

What are the 5 packet types used by EIGRP when communicating with other routers?

Answer 7

• Hello
• Request
• Update
• Query
• Reply

Question 8

What is the Hello packet used for?

Answer 8

• Detecting neighbors
• Making sure the neighbor is still up

Question 9

What is the Request packet used for?

Answer 9

Used to get specific information from one or more neighbors

Question 10

What is the Update packet used for?

Answer 10

Used to transmit routing and reachability information to other routers

Question 11

What is the Query packet used for?

Answer 11

Sent to search for another path during convergence

Question 12

What is the Reply packet used for?

Answer 12

Sent in response to a Query packet

Question 13

What is EIGRP’s reference bandwidth?

Answer 13

10 Gbps or 10⁷

Question 14

Which K values default to 1?

Answer 14

K1 and K3

Question 15

What 4 things do EIGRP Wide Metrics do?

Answer 15

• Accomodates up to 655 Tbps
• Scales by 65,535
• Delay measured in picoseconds
• adds 6th K value

Question 16

How is the Variance value computed if you want to put feasable successor routes in the RIB?

Answer 16

Feasable Successor metric divided by the Successor Metric and round up

Question 17

For Unequal cost load balancing how is traffic divided.

Answer 17

Proportionately based on the actual metric

Question 18

What is the EIGRP Hello timer on T1s or slower links?

Answer 18

Every 60 seconds

Question 19

What is the Hold timer?

Answer 19

3 times the Hello interval.

Question 20

What is the command to summarize a route in EIGRP?

Answer 20

Interface command: ip summary-address eigrp <as> <supernet> <mask></mask></supernet></as>

interface s0/1/0

ip summary-address eigrp 4 172.0.0.0 255.0.0.0 5

Question 21

During EIGRP neighbor establishment what is the purpose of the Pending state?

Answer 21

To defer sending and accepting any EIGRP messages containing routing information between these neighbors until their bidirectional connectivity has been confirmed

Question 22

During neighbor establishment what do the 2 neighbors do to confirm bidirectional connectivity?

Answer 22

They send each other Null update packets that contain no routing information but that have the Init flag set letting the neighbors know the neighborship is starting from scratch and once bidirectional communication is confirmed they each expect full routing updates.

Question 23

During neighbor establishment at what point does the neighborship transition from pending to full?

Answer 23

After both routers have their Null Update messages acknowledged.

Question 24

What are 3 ways the query boundary can be limited?

Answer 24

• summary route
• EIGRP stub feature
• filter routes with distribution lists