You are the network administrator for your company. You want to implement a routing protocol that can support
hierarchical routing, multiple vendor environments, and authentication, and provides fast convergence.
Which routing protocol will you implement?
A.
Enhanced Interior Gateway Routing Protocol (EIGRP)
B.
Open Shortest Path First (OSPF)
C.
Routing Information Protocol version 2 (RIPv2)
D.
Interior Gateway Routing Protocol (IGRP)
Explanation:
Open Shortest Path First (OSPF) is the routing protocol that accomplishes this task. The following are
characteristics of OSPF:
Conveges very quickly.
Uses cost to detemine the best route.
Uses Internet Protocol (IP) protocol 89.
Has a default administrative distance of 110.
Is an industry standard protocol (non Cisco-proprietary).
Supports Non-Broadcast Multi-Access (NBMA) networks such as frame relay, X.25, and Asynchronous
Transfer Mode (ATM). The default hello interval for NBMA networks is 30 seconds.
Supports point-to-point and point-to-multipoint connections.
Supports authentication.
Uses 224.0.0.6 as multicast address for ALLDRouters.
Uses 224.0.0.5 as multicast address for ALLSPFRouters.
Uses link-state updates and SPF calculation that provides fast convergence.
Recommended for large networks due to good scalability.
Uses cost as the default metric.
Supports VLSM.
Create minimal overhead due to its hierarchical design.
In OSPF networks, a hierarchical IP addressing design and the use of areas yields the following benefits:
Faster convergence
Reduced routing overhead
Confinement of network instability to a single area of the network
Electing a designated router (DR) in each area reduces update traffic because all updates occur through the
DR. The DR election is based on the router ID. This is the highest IP address of the active interfaces when no
loopback interface is configured. When a loopback address is present, its address is used for the purposes of
DR election. In either case, the router with highest router ID becomes the DR.
EIGRP and IGRP are incorrect because they are Cisco-proprietary routing protocols, and thus do not support
multiple vendor environments. They also do not support hierarchical routing. IGRP is no longer being supported
by Cisco.
RIPv2 is incorrect because it does not support hierarchical routing or provide fast convergence.
Objective:
Routing Fundamentals
Sub-Objective:
Compare and contrast distance vector and link-state routing protocolsCisco > Articles > Cisco Certification > CCNP > Shooting Trouble with IP
Cisco > Internetworking Technology Handbook > Open Shortest Path First (OSPF)