Lecture CCNA Exploration 4.0 (Kỳ 2) - Chapter 9: EIGRP

In this chapter, you will learn to: Describe the background and history of Enhanced Interior Gateway Routing Protocol (EIGRP), examine the basic EIGRP configuration commands and identify their purposes, calculate the composite metric used by EIGRP, describe the concepts and operation of DUAL, describe the uses of additional configuration commands in EIGRP.
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Lecture CCNA Exploration 4.0 (Kỳ 2) - Chapter 9: EIGRP Chapter 9: EIGRP CCNA Exploration version 4.0 1 Objectives • Describe the background and history of Enhanced Interior Gateway Routing Protocol (EIGRP). • Examine the basic EIGRP configuration commands and identify their purposes. • Calculate the composite metric used by EIGRP. • Describe the concepts and operation of DUAL. • Describe the uses of additional configuration commands in EIGRP. Học viện mạng Bach Khoa - Website: www.bkacad.com 2 Introduction to EIGRP Học viện mạng Bach Khoa - Website: www.bkacad.com 3 EIGRP • The main purpose in Cisco's development of EIGRP was to create a classless version of IGRP. • EIGRP includes several features that are not commonly found in other distance vector routing protocols like RIP (RIPv1 and RIPv2) and IGRP. • These features include: 1. Reliable Transport Protocol (RTP) 2. Bounded Updates 3. Diffusing Update Algorithm (DUAL) 4. Establishing Adjacencies 5. Neighbor and Topology Tables • Although EIGRP may act like a link-state routing protocol, it is still a distance vector routing protocol. Học viện mạng Bach Khoa - Website: www.bkacad.com 4 EIGRP • Roots of EIGRP: IGRP – Developed in 1985 to overcome RIPv1’s limited hop count – Distance vector routing protocol – Metrics used by IGRP
bandwidth (used by default)
delay (used by default)
reliability
load – Discontinued support starting with IOS 12.2(13)T & 12.2(R1s4)S Học viện mạng Bach Khoa - Website: www.bkacad.com 5 IGRP to EIGRP Traditional Distance Vector Enhanced Distance Vector Routing Routing Protocols Protocol: EIGRP • Use the Bellman-Ford or • Uses the Diffusing Update Algorithm Ford-Fulkerson algorithm. (DUAL) • Age out routing entries and • Does not age out routing entries nor uses periodic updates. uses periodic updates. • Maintains a topology table separate • Keep track of only the best from the routing table, which routes; the best path to a includes the best path and any loop- destination network. free backup paths. • When a route becomes • When a route becomes unavailable, unavailable, the router must DUAL will use a backup path if one wait for a new routing exists in the topology table. update. • Faster convergence due to the absence of holddown timers and a • Slower convergence due to system of coordinated route holddown timers. calculations. Học viện mạng Bach Khoa - Website: www.bkacad.com 6 EIGRP Capabilities and Attributes Học viện mạng Bach Khoa - Website: www.bkacad.com 7 EIGRP Message Format • The data portion of an EIGRP message is encapsulated in a packet. This data field is called Type/Length/Value or TLV. Học viện mạng Bach Khoa - Website: www.bkacad.com 8 EIGRP Message Format • The Autonomous System (AS) Number specifies the EIGRP routing process. – Unlike RIP, Cisco routers can run multiple instances of EIGRP. – The AS number is used to track multiple instances of EIGRP. • EIGRP Parameters contains – Weights – Hold time Học viện mạng Bach Khoa - Website: www.bkacad.com 9 EIGRP Message Format • TLV: IP internal contains – Metric field – Subnet mask field – Destination field • TLV: IP external contains – Fields used when external routes are imported into EIGRP routing process Học viện mạng Bach Khoa - Website: www.bkacad.com 10 Protocol Dependent Modules (PDM) Học viện mạng Bach Khoa - Website: www.bkacad.com 11 RTP and EIGRP Packet Types Học viện mạng Bach Khoa - Website: www.bkacad.com 12 RTP and EIGRP Packet Types • Purpose of RTP: to transmit and receive EIGRP packets • Characteristics of RTP – Involves both reliable & unreliable delivery of EIGRP packet
Reliable delivery requires acknowledgment from destination
Unreliable delivery does not require an acknowledgement from destination – Packets can be sent
Unicast
Multicast : Using address 224.0.0.10 Học viện mạng Bach Khoa - Website: www.bkacad.com 13 RTP and EIGRP Packet Types Học viện mạng Bach Khoa - Website: www.bkacad.com 14 RTP and EIGRP Packet Types Học viện mạng Bach Khoa - Website: www.bkacad.com 15 Hello Protocol Học viện mạng Bach Khoa - Website: www.bkacad.com 16 RTP and EIGRP Packet Types Học viện mạng Bach Khoa - Website: www.bkacad.com 17 RTP and EIGRP Packet Types • Update packets –Used to propagate routing information –Update packets are sent as a multicast when required by multiple routers, or as a unicast when required by only a single router. • Acknowledgement packets –Used to acknowledge receipt of update, query & reply packets –EIGRP acknowledgement packets are always sent as an unreliable unicast. Học viện mạng Bach Khoa - Website: www.bkacad.com 18 RTP and EIGRP Packet Types Học viện mạng Bach Khoa - Website: www.bkacad.com 19 RTP and EIGRP Packet Types Query & Reply ...