Enhanced Interior Gateway Routing Protocol (EIGRP) is a dynamic routing protocol that enables routers to exchange routing information efficiently. EIGRP utilizes various message types to establish and maintain neighbor relationships, share routing information, and ensure network convergence. Let’s delve into the key EIGRP messages that facilitate this communication:
Hello Messages:
Purpose: Establishing and maintaining neighbor relationships.
Frequency: Sent periodically to discover neighbors.
Content: Contains important parameters like AS number, router ID, and hold time.
Update Messages:
Purpose: Transmitting routing information.
Trigger: Sent when there is a change in the network topology.
Content: Carries information about reachable destinations, metric values, and more.
Query Messages:
Purpose: Requesting missing routing information during topology changes.
Scenario: Triggered when a router loses routes and needs updates from neighbors.
Content: Seeks specific information to complete the routing table.
Reply Messages:
Purpose: Responding to Query messages.
Scenario: Sent by routers possessing the requested routing information.
Content: Provides the missing details to the querying router.
Acknowledgment Messages:
Purpose: Confirming receipt of EIGRP packets.
Role: Ensures reliability in communication.
Content: Acknowledges successful reception of Hello, Update, Query, and Reply messages.