2. EIGRP

Question 1

What kind of routing protocol is EIGRP?

Answer 1

An enhanced distance vector

Question 2

What is DUAL and what does it do?

Answer 2

Diffusing Update Algorithm, algorithm that identifies network paths, provided fast convergence by using loop free back-up paths

Question 3

Can a border router transfer routes between ASNs?

Answer 3

Yes, but this is turned off by default

Question 4

What are PDMs and what do they do?

Answer 4

Protocol Dependent Modules, used by EIGRP to support multiple network protocols.

Question 5

What is the successor route?

Answer 5

The route with the lowest path metric to reach a destination

Question 6

What is the successor?

Answer 6

The next hop router for the successor route

Question 7

What is the feasible distance?

Answer 7

Metric value for the the lowest metric path to reach a destination

Question 8

What is the reported distance?

Answer 8

Distance reported by a router to reach a prefix. It is the FD of an advertising router

Question 9

What is the feasibility condition?

Answer 9

To be considered a back-up route, the RD must be lower than the FD locally.

Question 10

What is the feasible successor?

Answer 10

A route that satisfies the feasible condition

Question 11

How does EIGRP maintain its routes?

Answer 11

It creates its own Topology table and installs routes from the topology table into the routing table

Question 12

What is in the EIGRP topology table?

Answer 12

• Network prefix
• Neighbor that advertised the prefix
• Metris from each neighbor
• Values used to calculate the metric (total delay, minimum bandwith, load, reliability)

Question 13

What is the command to show the EIGRP topology?

Answer 13

show ip eigrp topology

Question 14

Does the EIGRP topology table show all links?

Answer 14

Not by default, with the command ‘show ip eigrp topology all links’ it can be shown

Question 15

What is the IP protocol number of EIGRP?

Answer 15

88

Question 16

Does EIGRP use unicast of multicast?

Answer 16

Both. Multicast if possible, unicast if necessary

Question 17

What is the IP for EIGRP?

Answer 17

224.0.0.10

Question 18

What is the MAC for EIGRP?

Answer 18

01:00:5e:00:00:0a

Question 19

What are the type of EIGRP packets?

Answer 19

• Hello
• Request
• Update
• Query
• Reply

Question 20

What is RTP and what does it do?

Answer 20

Reliable Transport Protocol, ensures that packets are delivered in order and that routers receive them

Question 21

What RTP values are used?

Answer 21

0 for no reply needed, all others ask for an ACK

Question 22

What packets do not need RTP acknowledgement?

Answer 22

Hello and ACK packets

Question 23

With RTP, what happens if an ACK is not received before the retransmit timer expires?

Answer 23

The router will notify the non-ack router to stop processing the multicast packets. Will start sending unicast untill they are fully synced again.

Question 24

How many times will EIGRP retry to send a packet that needs ACK?

Answer 24

16

Question 25

What EIGRP parameters must match to become neighbors?

Answer 25

- ASN - Subnet - K values - Authentication parameters

Question 26

What are the two type of EIGRP modes?

Answer 26

- Classic | - Named

Question 27

What are the three subsections of EIGRP named mode?

Answer 27

- Address family - Interface - Topology

Question 28

How is the EIGRP router-id selected?

Answer 28

Highest UP loopback, if not highest IP

Question 29

What is the command to apply settings on all interface in the named mode?

Answer 29

al-interface DEFAULT

Question 30

What is the maximum EIGRP hop count?

Answer 30

255

Question 31

What is the default maximum EIGRP hop count?

Answer 31

100

Question 32

What is the normal formula for EIGRP?

Answer 32

10 tot de macht van 7 delay in micros ------------------------------ + ---------------------- x 256 bandwith 10

Question 33

What is the wide metric formula for EIGRP?

Answer 33

10 tot de macht van 7 delay in picos ------------------------------ + ---------------------- x 65536 bandwith 10 tot de macht van 6

Question 34

How is the delay displayed?

Answer 34

Microseconds on show interface | Tens of microseconds if configured on the interface

Question 35

What type of authentication can be used on EIGPR?

Answer 35

MD5 for classis config or MD5 & SHA265 for named config

Question 36

What is the default maximum of ECMP of UCMP?

Answer 36

4

Question 37

What is the command to change the ECMP in EIGRP?

Answer 37

maximum-paths .... under classic | maximum-paths under topology in named

Question 38

What is the variance multiplier?

Answer 38

A value that determines the value for which unequal paths can be installed in the routing table. Any feasible successors FD with a value below the variance value are installed in the RIB

Question 39

How is the variance value calculated?

Answer 39

FD x variance multiplier

Question 40

What is important to remember about the variance multiplier?

Answer 40

It rounds up to the whole number

Question 41

What is the command to adjust the variance?

Answer 41

variance

Question 42

What is the difference between Passive & Active state?

Answer 42

- Passive is a stable topology | - Active is when a new path is calculated

Question 43

How can you check which EIGPR routes are installed in the RIB?

Answer 43

shiw ip route EIGRP

Question 44

How are routers of a different ASN displayed in the routing table and what is the AD?

Answer 44

D EX with AD 170