© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Configuring EIGRP Introducing EIGRP

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Flexible network design Multicast and unicast instead of broadcast address Manual summarization at any point 100% loop-free classless routing Easy configuration for WANs and LANs Load balancing across equal- and unequal-cost pathways Advanced distance vector Fast convergence Support for VLSM and discontiguous subnets Partial updates Support for multiple network-layer protocols EIGRP Features

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v EIGRP Key Technologies Neighbor discovery/recovery –Uses hello packets between neighbors Reliable Transport Protocol (RTP) –Guaranteed, ordered delivery of EIGRP packets to all neighbors DUAL finite-state machine –Selects lowest-cost, loop free, paths to each destination Protocol-dependent modules (PDMs) –EIGRP supports IP, AppleTalk, and Novell NetWare. –Each protocol has its own EIGRP module and operates independently of any of the others that may be running.

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v EIGRP Neighbor Table

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v DUAL Terminology Selects lowest-cost, loop-free paths to each destination AD = cost between the next-hop router and the destination FD = cost from local router = AD of next-hop router + cost between the local router and the next-hop router Lowest-cost = lowest FD (Current) successor = next-hop router with lowest-cost, loop free path Feasible successor = backup router with loop-free path (AD of feasible successor must be less than FD of current successor route)

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v EIGRP Topology Table

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v EIGRP IP Routing Table

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Example: EIGRP Tables Router C Tables:

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v EIGRP Packets Hello: Establish neighbor relationships. Update: Send routing updates. Query: Ask neighbors about routing information. Reply: Respond to query about routing information. ACK: Acknowledge a reliable packet.

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Initial Route Discovery

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v EIGRP Metric Same metric components as IGRP: –Bandwidth –Delay –Reliability –Loading –MTU EIGRP metric is IGRP metric multiplied by 256.

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v EIGRP Metric Calculation By default, EIGRP metric: Metric = bandwidth (slowest link) + delay (sum of delays) Delay = sum of the delays in the path, in tens of microseconds, multiplied by 256 Bandwidth = [10 7 / (minimum bandwidth link along the path, in kilobits per second)] * 256 Formula with default K values (K1 = 1, K2 = 0, K3 = 1, K4 = 0, K5 = 0): Metric = [K1 * BW + ((K2 * BW) / (256 – load)) + K3 * delay] If K5 not equal to 0: Metric = metric * [K5 / (reliability + K4)]:

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v A B C D Least bandwidth 64 kbps Total delay 6,000 A X Y Z D Least bandwidth 256 kbps Total delay 8,000 Delay is the sum of all the delays of the links along the paths: Delay = [delay in tens of microseconds] x 256 Bandwidth is the lowest bandwidth of the links along the paths: Bandwidth = [10,000,000 / (bandwidth in kbps)] x 256 EIGRP Metrics Calculation Example

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v EIGRP Metrics Are Backward-Compatible with IGRP

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Summary EIGRP capabilities include fast convergence and support for VLSM, partial updates, and multiple network layer protocols. EIGRP key technologies are neighbor discovery/recovery, RTP, DUAL finite-state machine, and PDMs. EIGRP uses three tables: neighbor table, topology table, and routing table. The routing table contains the best route to each destination, called the successor route. A feasible successor route is a backup route to a destination; it is kept in the topology table. EIGRP uses the same metric components as IGRP: delay, bandwidth, reliability, load, and MTU. By default, EIGRP metric equals bandwidth (slowest link) plus delay (sum of delays). EIGRP metrics are backward-compatible with IGRP; the EIGRP- equivalent metric is the IGRP metric multiplied by 256.

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v