EIGRP Routing Protocols and Concepts – Chapter 9 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public ITE PC v4.0 Chapter 1 1 Introduction Introduction ITE PC v4.0 Chapter 1 2 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public EIGRP  Roots of EIGRP: IGRP -Developed in 1985 to overcome RIPv1’s limited hop count -Distance vector routing protocol Mti db IGRP - M e t r i cs use d b y IGRP bandwidth (used by default)  Delay (used by default)  Delay (used by default) Reliability (not used by default)  Load (not used by default) Load (not used by default) -Discontinued support starting with IOS 12.2(13)T & 12.2(R1s4)S ITE PC v4.0 Chapter 1 3 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public EIGRP  EIGRP is a distance vector, classless routing protocol that was released in 1992 with IOS 9 21 released in 1992 with IOS 9 . 21 .  As its name suggests, EIGRP is an enhancement of Cisco IGRP (Interior Gateway Routing Protocol).  Both are Cisco proprietary protocols and only operate on Cisco Both are Cisco proprietary protocols and only operate on Cisco routers.  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 features that are not commonly found in other distance vector routing protocols like RIP (RIPv1 and RIPv2) and IGRP. These features include: –Reliable Transport Protocol (RTP) – Bounded U p dates p –Diffusing Update Algorithm (DUAL) –Establishing Adjacencies –Neighbor and Topology Tables Alth h EIGRP t lik li k tt ti t liti  Alth oug h EIGRP may ac t lik e a li n k -s t a t e rou ti ng pro t oco l , it i s still a distance vector routing protocol. –Note: The term hybrid routing protocol is sometimes used to define EIGRP. However, this term is misleading because EIGRP is not a hybrid between distance vector and link - state routing protocols - it is ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public hybrid between distance vector and link state routing protocols it is solely a distance vector routing protocol. Therefore, Cisco is no longer using this term to refer to EIGRP. EIGRP  The Algorithm  The Algorithm –EIGRP uses the Diffusing Update Algorithm (DUAL). –EIGRP does not send periodic updates and route entries do not age out out . –Only changes in the routing information, such as a new link or a li k b i il bl li n k b ecom i ng unava il a bl e cause a routing update to occur. – EIGRP routin g u p dates are still gp vectors of distances transmitted to directly connected neighbors. ITE PC v4.0 Chapter 1 5 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public EIGRP  Path Determination G – EI G RP's DUAL maintains a topology table separate from the routing table, which includes both the best path to a destination network and any backup destination network and any backup paths that DUAL has determined to be loop-free. If a route becomes unavailable DUAL – If a route becomes unavailable , DUAL will search its topology table for a valid backup path. If i t th t t i • If one ex i s t s, th a t rou t e i s immediately entered into the routing table. If d t i t DUAL f • If one d oes no t ex i s t , DUAL per f orms a network discovery process to see if there happens to be a backup path that did not meet the requirement of ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public that did not meet the requirement of the feasibility condition. EIGRP  Convergence –EIGRP does not use holddown timers. Instead loop free paths are – Instead , loop - free paths are achieved through a system of route calculations (diffusing computations) that are performed in a coordinated that are performed in a coordinated fashion among the routers. –The detail of how this is done is beyond the scope of this course, but the result is faster convergence than traditional distance vector routing protocols. ITE PC v4.0 Chapter 1 7 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public EIGRP EIGRP EIGRP Message Format  EIGRP Header EIGRP Header Data link frame header - contains source and destination MAC address IP packet header - contains source & destination IP address EIGRP packet header - contains AS number AS number Type/Length/Field - data portion of EIGRP message In the IP p acket header , p, the protocol field is set to 88 to indicate EIGRP the destination address is set to th lti t2240010 th e mu lti cas t 224 . 0 . 0 . 10 . If the EIGRP packet is encapsulated in an Ethernet frame,  the destination MAC address is ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public  the destination MAC address is also a multicast address: 01-00- 5E-00-00-0A. EIGRP EIGRP  All fields are shown to provide an accurate picture of the EIGRP message format. However, only the fields relevant to the CCNA candidate are discussed. EIGRP packet header contains  EIGRP packet header contains –Opcode field •Update • Query Query •Reply •Hello –Autonomous System number S • The A S number is used to track multiple instances of EIGRP.  EIGRP Parameters contains – Weights Weights •EIGRP uses for its composite metric. •By default, only bandwidth and delay are weighted. Both are set to 1. •The other K values are set to zero. –Hold time •The amount of time the EIGRP neighbor receiving this message ITE PC v4.0 Chapter 1 9 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public neighbor receiving this message should wait before considering the advertising router to be down. EIGRP EIGRP  TLV: IP internal contains (EIGRP routes within an autonomous system) – Metric field (Delay and Bandwidth) – Metric field (Delay and Bandwidth) •Delay is calculated as the sum of delays from source to destination in units of 10 microseconds. •Bandwidth is the lowest confi g ured bandwidth g of any interface along the route. –Subnet mask field •The subnet mask is specified as the prefix length or the number of network bits in the bt k su b ne t mas k . •255.255.255.0 is 24 –Destination field • t h e add r ess o f t h e dest in at i o n n et w o rk. t e add ess o t e dest at o et o •Although only 24 bits are shown in this figure. •If a network address is longer than 24 bits, then the Destination field is extended for another 32 bits  TLV: IP external contains –Fields used when external routes are imported into ITE PC v4.0 Chapter 1 10 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public EIGRP routing process – import or redistribute a route into EIGRP. [...]... 65,536 - 4, 294 ,96 7, 295 "32-bit AS Numbers" refers to AS Numbers in the range 0 - 4, 294 ,96 7, 295 ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 23 Basic EIGRP Configuration EIGRP autonomous system number actually functions as a process ID –The vast majority of companies and institutions with IP networks do not need an AS number –The ISP is responsible for the routing of... route in the routing table fails, the best backup route is immediately added to the routing table ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 19 EIGRP Administrative Distance (AD) –Defined as the trustworthiness of the source route EIGRP default administrative distances –Summary routes = 5 Summary –Internal routes = 90 –Imported routes = 170 ITE PC v4.0 Chapter 1 ©... EIGRP Metrics –Bandwidth – EIGRP uses a static bandwidth to calculate metric –Most serial interfaces use Most a default bandwidth value of 1.544Mbos (T1) –The value of the bandwidth b d idth may or may not reflect the actual SPEED of the interface –If actual SPEED of the link differs from the default bandwidth value, then you should modify the bandwidth value, The default bandwidth for ethernet is... also displayed: –Distance: internal 90 external 170 ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 30 Basic EIGRP Configuration We will configure the bandwidth later Examining the Routing g g Table The show ip route command is also used to verify EIGRP –EIGRP routes are denoted in a routing table by the letter “D” –EIGRP is a classless routing protocol (includes th ti... queries, and reply packets ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 29 EIGRP The show ip protocols command is also used to verify that EIGRP is enabled Remember, the process ID must be , p the same on all routers for EIGRP to establish neighbor adjacencies and share routing information EIGRP's internal and external administrative distances are also displayed: –Distance:... Authentication A th ti ti EIGRP can – Encrypt routing information – Authenticate routing information It is good practice to authenticate transmitted routing information – This practice ensures that routers will only accept routing information from other routers that have been configured with the same password or authentication information Note: Authentication does not encrypt the router's routing table http://www.ciscopress.com/articles/article.asp?p=11711 69& seqNum=3... Process IDs –This is a collection of networks under the control of a single authority (reference RFC 193 0) –AS Numbers are assigned by IANA ARIN not IANA –Entities needing AS numbers ISP Internet Backbone prodiers Institutions connecting to other institutions using AS numbers These ISPs and large institutions use the exterior gateway routing protocol or BGP, to propagate routing information 16-bit and 32-bit... minimizes use of bandwidth ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 18 EIGRP Diffusing Update Algorithm (DUAL) –Purpose •EIGRP’s primary method for preventing routing loops And also hold-down timers and split horizon, too –Advantage of using DUAL •Provides f f t convergence time by keeping a li t of l P id for fast ti b k i list f loopfree backup routes –DUAL maintains... several t t l different protocols i.e IP, IPX & AppleTalk PDMs are responsible for the specific routing task for each network layer protocol –As you can see in the figure, EIGRP uses different EIGRP packets and maintains separate neighbor, topology, i t i t i hb t l and routing tables for each Network layer protocol •The IP-EIGRP module is responsible The IP EIGRP for sending and receiving EIGRP packets... routers in the EIGRP routing domain must use the th same process ID number (autonomous-system b number) ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 25 Basic B i EIGRP C fi Configuration ti The Network Command Functions of the network command –Enables interfaces to transmit & receive EIGRP updates –Includes network or subnet in EIGRP updates Example p –Router(config-router)#network . EIGRP Routing Protocols and Concepts – Chapter 9 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public ITE PC v4.0 Chapter 1 1 Introduction Introduction ITE PC v4.0 Chapter 1 2 ©. vector routing protocols like RIP (RIPv1 and RIPv2) and IGRP. These features include: –Reliable Transport Protocol (RTP) – Bounded U p dates p –Diffusing Update Algorithm (DUAL) –Establishing. system) – Metric field (Delay and Bandwidth) – Metric field (Delay and Bandwidth) •Delay is calculated as the sum of delays from source to destination in units of 10 microseconds. •Bandwidth