What is EIGRP (Enhanced Interior Gateway Protocol)?

What is EIGRP?

The distance vector protocol is an elegant version of the IGRP with the sole purpose.

It has the following features:

• RTP Yes (Trusted Transport Protocol)
• Maintains limited updates
• Broadcast update algorithm (DUAL)
• Establishing contiguities
• Preserves topology or neighboring tables

Data in an EIGRP message is included in a TLV-style data field (Type, Length, Value).

EIGRP Multiprotocol

EIGRP is capable of routing different protocols, some examples:

• IP
• Apple Talk

This is due to the use of individual protocol modules (PDMs), which are responsible for routing tasks specific to each network layer protocol.

For example:

The IP-EIGRP module is responsible for sending and receiving IP-coated EIGRP packets and using DUAL to create and maintain the IP routing table. EIGRP uses different packets and provides separate neighbors, topology and routing tables for each protocol in the Network layer.

The IPX EIGRP module is responsible for exchanging routing information about IPX networks with other IPX routes.

RTP and EIGRP Package Types

The Trusted Transport Protocol is the protocol used by EIGRP to deliver and receive the same packets, which is designed to operate as a routing protocol that runs outside the network layer so that services such as UDP and TCP cannot be accessed.

Even if your name has a reliable word, even if it is possible to obtain a delivery through an unreliable ETPRP, you can identify these packages because a reliable RTP requires a confirmation of receipt that requires nothing.

RTP can send packets with UNICAST or MULTICAST, the latter uses a reserved address:

Routers with EIGRP can discover their neighbors through a package called “GREETING”, in most networks “greeting” packets are sent every 5 seconds and help keep the neighbors and their routes visible When the greeting is answered.

The wait time tells the router the maximum time it will wait before receiving the next “greet” before declaring its neighbor “inaccessible”.

As a rule, the waiting time is 3 times the salutation interval.

Wait time before reporting a router = “dead”

(It takes the router to send an e-mail) (3)

When the timeout expires, the route is declared inactive and a new route is searched using queries.

Limited updates

EIGRP reserves some reserves as it does not send periodic updates on update packages, ONLY IN THE METRIC OF ROAD CHANGES.

It is worth noting that these updates are PARTIAL because when this happens, the entire contents of a table are not sent, only information about route changes is sent.

EIGRP also takes care to limit this route change information to the affected routers. The partial update is automatically updated to “Limits”, so only routers that require this information.

Sending ONLY the necessary routing information and ONLY to the routers in need minimizes the bandwidth required to send packets.

Administrative Distance

The administrative distance is the “degree of reliability ın of the route.

EIGRP has 90 administrative distances for internal routes and 170 administrative distances for routes imported from an external source (including default routes)

Compared to other protocols, the EIGRP has less administrative distance, in other words, IT IS MORE RELIABLE.


It accepts security settings and can encrypt and verify your routing information.

It is recommended that authentication is always performed on the transmitted routing information, ensuring that routers will only accept routing information from routers configured with the same password or authentication information.

Protocols such as:

· RIPv2

They also accept encryption in routing information.

Related Posts

What is Cisco Packet Tracer?
How to Install Packet Tracer
Download Packet Tracer
What is RIP
What is RIPv2

Source: https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/16406-eigrp-toc.html