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  1 Ch.5 -EIGRP CCNP 1 version 3.0Rick GrazianiCabrillo College * Updated by HoonJaeLee(DongseoUniv.)2006. 3. 3 2 Overview Note: I have added additional information and slides to this presentation which is not part of the curriculum. This was done to better explain many of the EIGRP operations and technologies.  2 EIGRP • “Enhanced”Interior Gateway Routing Protocol • Based on IGRP and developed to allow easy transition from IGRP to EIGRP. (“Like IGRP+”) • Cisco proprietary , released in 1994 • EIGRP is an advanced distanceadvanced distance--vector vector  routing protocol that relies on features commonly associated with link-state protocols. (sometimes called a hybrid routing protocolhybrid routing protocol ). • Note : The Hybrid term sometimes misleads people into thinking EIGRP has the topology benefits of a link state routing protocol. It does not. EIGRP is a distance vector routing protocol and suffers from all of the same disadvantages of any other distance vector routing protocol, i.e. routing loops. • Note : “Often described as a hybrid routing protocoloffering the best of distance-vector and link-state algorithms.”-I would say “ features of distance-vector and link-state”not necessarily “the best.” IGRP and EIGRP: A migration path  Automatic redistribution between IGRP and EIGRP as long as “AS”numbers are the same!!Outside routes (redistributed) are tagged as external routes.No differentiation between internal and external routes.Maximum Hop Count = 224Maximum Hop Count = 255 bandwidth = (10,000,000/ bandwidth kbps ) * 256delay = ( delay /10) * 25632 bit metric for bandwidth and delaybandwidth = (10,000,000/ bandwidth kbps )delay = delay /1024 bit metric for bandwidth and delayClassless Routing Protocol • VLSM, CIDRClassfulRouting Protocol EIGRPIGRP  3 5 EIGRP and IGRP compatibility •  Automatic redistribution occurs when the same AS number is used for EIGRP and IGRP. • EIGRP scales the IGRP metric by a factor of 256. • IGRP reduces the metric by a factor o 256. 6 EIGRP and IGRP compatibility • EIGRP will tag routes learned from IGRP, or any outside source, as external because they did not srcinate from EIGRP routers. • IGRP cannot differentiate between internal and external routes. 10,476 = 6,476(BW)+2,000(DLY)+2,000(DLY) IGRP Metrics! (Does not multiply by 256. ExternalExternal  4 Metric Calculation (Review) EIGRPbandwidth is in kbps  –  k1 for bandwidth  –  k2 for load  –  k3 for delay  –  k4 and k5 for Reliability Router(config-router)# metric weights tosk1 k2 k3 k4 k5  Features of EIGRP • Classless Routing Protocol (VLSM, CIDR) • Faster convergence times and improved scalability • Multi-protocol support: TCP/IP, IPX/SPX, Appletalk – There is no IPX/SPX or Appletalkin CCNA or CCNP • Rapid Convergenceand Better handling of routing loops –(DUAL) (coming) • Efficient 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 that 50% of link’s bandwidth EIGRP packets. • PDM (Protocol Dependent Module)  – Keeps EIGRP is modular  – Different PDMscan be added to EIGRP as new routed protocols are enhanced or developed: IPv4, IPv6, IPX, and AppleTalk • Unequal-cost load balancing same as IGRP (unlike OSPF)  5 9 Easy to implementDifficult to implementScalable, but no hierarchical design Scalable; administratively defined “areas”provide manageable hierarchy Proprietary; Cisco routers onlyOpen standard; multivendor support  Automatic route-summarization and user-defined route summaries Administrator can define route summarization Supports CIDR and VLSM, rapid convergence, partial updates, neighbor discoverySupports CIDR and VLSM, rapid convergence, partial updates, neighbor discovery EIGRPOSPF Equal-cost load balancingUnequal-cost load balancing OSPF versus EIGRP 10 EIGRP Terminology • 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 neighbor table for each protocol that EIGRP supports. • Topology table  –Every EIGRP router maintains 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 maintained in the topology table. • Routing table  –EIGRP chooses the best routes to a destinationfrom 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   –A feasible 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 fora destination can be retained in the topology table.
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