Definitions EIGRP and How to configuration EIGRP

Knowledge About EIGRP 

 EIGRP? What is that?

1. Intriducing EIGRP

 EIGRP is a Cisco-proprietary Hybrid routing protocol, incorporatingfeatures of both Distance-Vector and Link-State routing protocols.

2. Functions and Characteristic of EIGRP 

EIGRP adheres to the following Hybrid characteristics:

1. EIGRP uses Diffusing Update Algorithm (DUAL) to determine the best path among all “feasible” paths. DUAL also helps ensure a loop-free routing environment.
2. EIGRP will form neighbor relationships with adjacent routers in the same Autonomous System (AS)
3. EIGRP traffic is either sent as unicasts, or as multicasts on address 224.0.0.10, depending on the EIGRP packet type.
4. Reliable Transport Protocol (RTP) is used to ensure delivery of most EIGRP packets.
5. EIGRP routers do not send periodic, full-table routing updates. Updates are sent when a change occurs, and include only the change.
6. EIGRP is a classless protocol, and thus supports VLSMs. 

Other characteristics of EIGRP include:

1. EIGRP supports IP, IPX, and Appletalk routing.
2. EIGRP applies an Administrative Distance of 90 for routes originating within the local Autonomous System.
3. EIGRP applies an Administrative Distance of 170 for external routes coming from outside the local Autonomous System
4. EIGRP uses Bandwidth and Delay of the Line, by default, to calculate its distance metric. It also supports three other parameters to calculate its metric: Reliability Load, and MTU.
5. EIGRP has a maximum hop-count of 224, though the default maximum hop-count is set to 100 

EIGRP, much like OSPF, builds three separate tables:

1. Neighbor table – list of all neighboring routers. Neighbors must belong to the same Autonomous System
2. Topology table – list of all routes in the Autonomous System Routing table – contains the best route for each known network

3. Command to configuration EIGRP