October 11th Cisco 2 Features of EIGRP Classless -- Routing Protocol (VLSML CIDR) Faster convergence times and improve scalability Multiprotocol support: TCP/IP IPX/SPX, Appletalk -- There is no IPX/SPX on Appletalk in CCNA or CCNP Rapid Convergence and better handling of routingloops--(DUAL) (coming) Effecient use of bandwidth -- Partial, bounded updates: Incremental updates only to the routers that need them. --- Minimal bandwidth consumption: Uses Hello packets and EIGRP packets by default use no more than 50% of link's bandwidth EIGRP packets. PDM -- Protocol Dependent Module -- Keeps EIGRP is modular -- Different --------------------------- EIGRP Terminology Neighbor table Topology table Routing table successor feasible successor Neighbor table -- Each EIGRP router maintains a neighbor table that lists adjacent routers. This table is comparable to the adjacency database used by OSPF. There is a niehgbor table for each protocol that EIGRP supports. Topology table -- Every EIGRP router maintsa topology table for each configured network protocol. This table includes route entries for all destinations that the router has learned. All elarned routes to a destination are maintained in the topology table. Routing table -- EIGRP chooses the best routes to a destination from the topology table and places these routes in the routing table. Each EIGRP router maintains a routing table for each network protocol. Successor - A successor is a route selected as the primary route to use to reach a destination. Successors are the entries kept in the routing table. Multiple successors for a destination can be retained in the routing table. Feasible successor -- AW feasiable successor is a backup route. These routes are selected at the same time the successors are identified, but are kept in the topology table. Multiple feasible successors for a destination can be retained in the topology table. It is like the back up successor. ------------------------------ Neighbor Table - Each EIGRP router maints a neighbor table that lists adjacent routers. This table is comparable to the adjacency databased used by OSPF. There is a niehgbor table for each protocol that EIGRP uses. RouterC#show ip eigrp neighbors IP-EIGRP neighbors for process 44 H -- Address -- Interface -- Hoold -- Uptime -- SRTT - RTO Nieghbor address -- The network layer address of the neihgbor routers. Queue count: the number of packets waiting in queue to be sent. If this value is constantly higher than zero, then there mnay be a congestion problem at the router. A zero means that there are no EIGRP packets in the queue. Smooth Round Trip Timer (SRTT) -- The average time it takes to send and receive packets from a neighrbor -- This timer is used to determine the retransmit interval (RTO) Hold Time: The interval to wait without receiving anything form a neighbor before considering the link unavaibale. Originally, the expected packet was a hello packet, but in current Cisco IOS software releases, any EIGRP packets received after the first hello will reset the timer. How much time do you wait until you figure that the router doesn't exist? Note that an EIGRP router can maintain multiple neighr botables, one for each L3 protocol running (for example, IP, AppleTalk). A router must run a unikque EIGRP process for each routed protocol. You can set your "hold time". ------------------------------ Topology table - Each EIGRP router maints a topology table for each configured network protocol. - This table includes route entries for all destinations that the router has learned. - All learned routes to a destination are mainted in the topology table. --- EIGRP uses its topology table to store all the information it needs to calculate a set of distances and vectors to all reachable destinations. "show ip eigrp topology" Topology Table -- Talk to neighbors. Neighbors neighbors talk to each other, big giantgrid is set up. ------------------------------ Topology Table - Extra Information ------------------------------ Since EIGRP has a topology table, does this make it a link-state routing protocol? OSPF collects topology information from all over the place and puts it together. No, the information in the topology table is not in the form of LSAs describing the complete network topology LSA = Link-State Advertisement The EIGRP topology table contains information about paths through the router's adjacent neighbors. Also, EIGRP does not perform shortest-path calculation by calculating the shortest-path tree, but instead uses the DUAL algorithm. What is the shortest-path algorithm? ------------------------------ IP Routing Table - EIGRP chooses the best routes (that is, successor) to a destination from the tpology table and places these routes in the routing table. - Each EIGRP router maints a tpoloy table for each network ptocol. - EIGRP displays both internal EIGRP routes and external EIGRP routes. "show ip route" ------------------------------ The routing table contains the routes installed by DUAL as the best loop-free paths to a given destination. - EIGRP will maintain up to four routes per destination. These routes can be of equal, or unequal cost (if using the variance command) ------------------------------ Neighbor discovery and recovery --- We discover our neighbor tables Reliable Transport Protocol ---- DUAL finite-state machine Protocol-specific modules -- Modular, certain kind of modularity Four key technologes set EIGRP apart from IGRP (those are them)