Category: CCNA

Cisco Certified Network Associate certification resources
CCNA January 15, 2020

Successor, Feasible Successor and Feasible Distance

Successor -A successor route is the best route to a destination network. EIGRP uses the successor route to forward traffic to a destination. This is the router which is stored in the routing table. A successor route is based on the advertised distance from the neighbor. A successor route is a least-cost route to the...
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CCNA January 13, 2020

What is DUAL?

The diffusing update algorithm (DUAL) is the algorithm used by EIGRP routing protocol to make sure that a given route is recalculated globally whenever it might cause a routing loop. It is guarantees loop-free and backup paths throughout the routing domain. EIGRP store all available backup routes using diffusing update algorithm and then adapt the...
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CCNA January 13, 2020

How to Calculate EIGRP Metric

EIGRP automatically calculates the routing table metric to choose the best path. But it is important that the network administrator understands how to calculate EIGRP metric. The default formula for the composite metric is: [k1 x Bandwidth + k3 x delay] x 256 By default K1 and K3 is equal to 1 so the formula...
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CCNA January 12, 2020

Introduction to Delay Metric

Delay Metric is the measure of the time it takes a bit to be transmitted to an adjacent neighbor. The delay metric (DLY) is a constant value based on the type of link to which the interface is connected. The value is expressed in microseconds, the one-millionth of a second.  In the EIGRP metric calculation,...
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CCNA January 12, 2020

Introduction to Bandwidth Metric

EIGRP and OSPF both are using bandwidth metric which is a static value for calculating routing metrics. The bandwidth is displayed in kilobits per second (kb/s). The default bandwidths for different interfaces are: Serial Interface – 1544 kb/s Ethernet is – 10,000 kb/s FastEthernet – 100,000 GigaEthernet – 1,000,000 TenGig – 10,000,000 Figure 1 illustrates...
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CCNA January 11, 2020

EIGRP Composite Metric – Exclusive Explanation

A composite metric is a number calculated based on several different components that determine the preferred route. By default, EIGRP uses bandwidth and delay to calculate the preferred path to a network. The reliability and load can also be used, but are not recommended, because they typically result in a frequent recalculation of the topology...
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CCNA January 11, 2020

What is EIGRP Topology Table

EIGRP uses a neighbor table, topology table, and IP routing table. The neighbor table maintains a state of neighbors. The topology table is used to store information about all known routes received from all neighbors. EIGRP Update messages send the routers’ EIGRP topology tables. The EIGRP topology table is a database of possible routes. Each...
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Neighbour-Adjacency
CCNA January 10, 2020

Introduction to EIGRP Neighbor Adjacencies

Before exchanging any EIGRP update packets between routers, EIGRP must first discover its neighbor. EIGRP neighbor is an adjacent router running EIGRP on directly connected networks. EIGRP Hello packets are used to establish and maintain neighbor adjacencies. Several parameters between the two routers must match to become neighbors; for example, the same autonomous system number...
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CCNA January 9, 2020

Examine EIGRP in the Routing Table

We can verify the EIGRP in the routing table using the “show ip route” command. It is important to verify the information in the routing table to ensure that it is populated as estimated, based on configurations entered. The automatic summarization is enabled by default before in the ISO 15. It is important to know...
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CCNA January 8, 2020

Introduction to EIGRP Neighbors

EIGRP-enabled routers to establish neighbor adjacencies with other EIGRP-enabled routers by exchanging EIGRP Hello packets. Without establishing neighbor adjacencies routers cannot send or receive any updates. Using the “show ip eigrp neighbors” command, we can examine the neighbor’s table and verify EIGRP adjacencies. Figure 1 illustrates the output of the “show ip eigrp neighbors” command....
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