EIGRP Questions and Answer

Get answers to frequently asked questions about EIGRP. Learn about EIGRP tables, packets, neighbors, authentication, and more.

EIGRP Questions and Answer
1. What is EIGRP?
The EIGRP is an advanced protocol for the distance vector routing which is used
for an automated routing configuration and decisions within a computer network.
This EIGRP or the Enhanced Interior Gateway Routing Protocol was designed as
a proprietary protocol by the Cisco Systems, and currently, this protocol is only
available in the routers of Cisco.
2. What are the different tables in EIGRP?
The EIGRP protocol mainly uses three types of tables to maintain the database of
its which are the Neighbour table, Routing table and the Topology table.
3. Explain the different tables used in EIGRP.
Neighbour Table: From the name of the table it can be assessed that this table
holds the data or the information of the neighbour routers and this information is
collected by the usage of the Hellos.
Routing Table: This table consists of the possible best route for a particular
destination. To show all the available routes “show ip route” command is used.
Topology Table: This table consists of various vital information about a
network which includes all of the paths to a destination learnt from the
neighbours of the EIGRP. To show the topology table command “show ip eigrp
topology” is used.
4. Why EIGRP is called hybrid protocol?
For a hybrid routing protocol combination of two protocols are required which
are the distance vector routing protocol and the Link State Routing Protocol.
EIGRP is an advanced protocol for the distance vector routing, and also the
EIGRP provides the update of link state when changes occurred in the link state.
Thus EIGRP is considered as a hybrid protocol.
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5. What are the different packets in EIGRP?
For the communication process with the neighboring routers, the EIGRP
protocol uses a total of six different types of packets. These six packets are the
Hello packets, Acknowledgement packets, Update packets, Query packet, Reply
packets and the Request packets.
6. Conditions for EIGRP neighbors.
There is a total of six conditions which need to be satisfied for the EIGRP
neighbours. These six conditions are:
1. The neighboring router needs to receive and send the IP packets to other
routers.
2. Primary IP address needs to reside in the same subnet.
3. In command of the router configuration same ASN must be used.
4. No passive router is allowed in the connected interface.
5. K values need to match in this case.
6. Neighbour authentication must be passed when configured.
7. What settings must match between two routers in order to become EIGRP
neighbors?
Five settings must match in order to become EIGRP neighbour which are:
1. Both routers need to in the same AS.
2. Same K values must be used by both routers.
3. Both routers need to in the identical primary subnet.
4. Interface which is faced by each other must not passive.
5. Same authentication configuration must be followed by both routers.
8. What is meant by active and passive states in EIGRP?
Active State: Active state in the EIGRP defines that it is a state when a router
goes through the process of route re-computation.
Passive State: In the EIGRP when a specific router does not perform any route
re-computation it is considered that the route is in the passive state.
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9. What are the different k-values used in EIGRP?
There are a total of five K values which are used in the EIGRP and out of these
five only four K value components are used. These components are the
bandwidth, delay, load, reliability and MTU where MTU is not used for route
calculation.
10.What are the advantages of EIGRP other routing protocol?
The main advantages of EIGRP routing protocols are the:
1. Large dynamic multipoint VPN deployments through the superior scaling
of Interior Gateway Protocol.
2. The entire routing table is not propagated when changes occurred in the
system.
3. Easy switch to the IPv6 which consists multi-address family support for
both the IPv6 and the IPv4 network.
4. To change in the network topology faster rapid convergence time
supported.
5. Through unequal cost load sharing and equal cost multipath links can be
used more efficiently.
11.What is advertised distance?
The advertised distance is also considered as the reported distance which is the
distance between a destination router and a given neighbor router within a
network.
12.What is successor?
In EIGRP a successor defines that it is a typical type of path of which the
reported distance is lesser than the feasible distance. This path is considered as a
backup route. The EIGRP consist of a total of six feasible successors in the table
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of topology.
13.What types of authentication is supported by EIGRP?
The EIGRP consists of a total of two types of authentication process which are
router authentication and MD5 authentication.
14.What is feasible successor?
In the EIGRP feasible successor is considered as a path of which reported
distance is lesser than the feasible distance. The feasible successor is also
considered as a backup route.
15.What happen when we enable passive interface in EIGRP?
In the EIGRP protocol when the passive interface is enabled, it stops both the
incoming and the outgoing routing packets. Thus both receiving and sending of
the hello packet is stopped.
16.Can you configure more than one EIGRP autonomous system on the same
router?
Yes, more than one EIGRP autonomous system can be configured on the same
router. This configuration has been done in the at the point of redistribution
where two autonomous systems are interconnected.
17.When you configure EIGRP, how can you configure a network statement with a
mask?
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While configuring the EIGRP, it can be masked with a wildcard mask. The mask
should have wildcard bits where 1 represents do not care, and 0 represent a
match. As an example 0.0.255.255 represents a match in the first two octets.
Without the usage of the wildcard mask routers will send EIGRP packets to
some external network.
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