What is EIGRP – Enhanced Interior Gateway Routing Protocol.

  • It is an advanced distance vector & Hybrid Routing
  • It is not used distance for the best path but still hops count will be forwarded in EIGRP updates.
  • Next hop calculates by a source of update (this feature of Distance vector routing Protocol).
  • In EIGRP three table made: Neighbor Table, Topology Table, Routing Table (this feature of Link State Routing Protocol).
  • It is a classless routing Protocol: When a Router update of any network then it will send same network ID or Subnet this way called classless.
  • It is layer three routing Protocol: encapsulate with IP packets used 88 port no.
  • AD (Administrative Distance) for the same domain or internal route used 90.  AD (Administrative Distance) for the different domain or external route used 170.
  • EIGRP work on AS (Autonomous System): which share same routing policies and its control by a single network Admin.

What  Is EIGRP In Networking

Above is the properties of EIGRP, I Hope you know these all things and this will help you to shine your EIGRP memory.

Now my concern is that EIGRP to make communication possible inside an AS & how EIGRP will form its neighbour???????

what is eigrp

#Router EIGRP <1-65535> AS number range: This is the command for enabling EIGRP on a Router.

Note* on neighbour Router AS must be same.

#Network this is class A & network Bit 8.

By this command all interface where the 8 Bit match & EIGRP network enables.

For example:

what is eigrp in networking

Wildcard Mask used for matching that which OCTET will Match for the network.

When EIGRP enable on an Interface:

  1. A router will start dynamic neighbour discovery on that interface.
  2. The router will add network present on that interface to local topology table.
  3. A router will discover neighbour with hello message uses multicast address

what is eigrp networking

When hello message sends then first match the parameter for neighbour ship after that it will become a neighbour.

You also read that how to work DHCP Dora process

Hello and dead interval time:
  1. For P2p and Ethernet: hello 5 sec and dead 15 sec.
  2. For Slow links like frame relay: hello 60 sec and dead 180 sec.

Hello message check neighbour is alive or not. Hello message sends only when a state of Router is UP and line protocol of Router also UP. Mainly hello message use when two routers are indirectly connected.

A parameter of Hello message:
  1. AS number must match
  2. K values Must match: EIGRP use composite metric in hello packets with the router will tell each other what k value they are using for metric calculation. By default, K1, k3 is used but we have five k values.

what is eigrp 1

  1. Authentication (if configured) can be different.
  2. Hold time: how long you have to wait for me.

This all is about for basic of EIGRP. This information helps you about basic knowledge of EIGRP.

Find below some show command for troubleshooting:

#To Show IP protocol summary: for this command find the running protocol on a device.

#Show Process CPU | include EIGRP

#To Show IP EIGRP interface: detail of EIGRP on all interface

#Show IP protocol: detail about protocol

#Show IP EIGRP interface detail F0/0: detail of EIGRP on a single interface