Networking
CCNA tutorials, Cisco guides, and enterprise networking insights for IT professionals.
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...
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...
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....
How to Configure EIGRP Passive-Interface
A passive interface is used in all routing protocols, where we can stop sending updates from a specific interface. The behavior varies from one protocol to another. In EIGRP, using the passive-interface, we stop sending outgoing hello packets; therefore, the router cannot form any neighbor adjacencies via the passive interface. This behavior stops both outgoing...
The Network Command – Exclusive Explanation
The network command has the same function as in all IGP routing protocols. It enables any interface on this router that matches the network address. It enables EIGRP routing on an interface, using the command in router configuration mode and enter the classful network address for each directly connected network. The command syntax is as...
Mastering EIGRP Router ID Configuration
EIGRP router ID is a 32-bit unique identifier identifying the router in the EIGRP domain. The router ID (RID) is represented in the same way as the IPv4 address. The router ID is used both in EIGRP and OSPF, while the role of the router ID is more significant in OSPF. EIGRP automatically selects the...
Introduction to “Router EIGRP” Command
The “router” command in global configuration mode is an important command for start configuration of any dynamic routing protocol. The topology displayed in Figure 1 is used to configure and demonstrate the EIGRP routing protocol. Figure 2 (marked with a red triangle) illustrates the “router ?” with question marks to demonstrate the list of dynamic...
Introduction to Autonomous System Numbers (ASNs)
Autonomous system numbers (ASNs) is a unique identifier that is globally available and allows its autonomous system to exchange routing information with other systems. An Internet Assigned Numbers Authority (IANA) globally assigned autonomous system is a group of networks under the administrative control of a single body that presents a common routing policy to the...
EIGRP Packet Types – Exclusive Explanation
EIGRP uses 5 different types of packet in communication with its neighbours. EIGRP packets are sent with reliable or unreliable delivery and can be sent as a unicast, multicast, or sometimes both. EIGRP packet types are also called EIGRP packet format or EIGRP messages. The details of the EIGRP packets are the following: EIGRP Hello...
What is a Reliable Transport Protocol (RTP)
EIGRP uses a Reliable Transport Protocol (RTP) to deliver and receive EIGRP packets instead of TCP and UDP. Reliability is a key feature of EIGRP, and it is designed to enable fast update delivery and data reception tracking.EIGRP was designed as a network-layer independent routing protocol. This allows EIGRP to be used for protocols other...