Introduction to Dynamic Routin g Protocol g Routing Protocols and Concepts – Chapter 3 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public ITE PC v4.0 Chapter 1 1 Objectives  D esc ri be th e r o l e o f dy n a mi c r ou tin g p r o t oco l s a n d escbe eoeodya cou gpoocosad place these protocols in the context of modern network design.  Identify several ways to classify routing protocols.  Describe how metrics are used by routing protocols Describe how metrics are used by routing protocols and identify the metric types used by dynamic routing protocols.  Determine the administrative distance of a route and describe its importance in the routing process.  Identify the different elements of the routing table. ITE PC v4.0 Chapter 1 2 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Dynamic Routing Protocols  D y n a mi c r ou tin g p r o t oco l s a r e usua ll y y a c ou g p o oco s a e usua y used in larger networks to ease the administrative and operational overhead fi ltti t o f us i ng on l y s t a ti c rou t es.  Typically, a network uses a combination f b th d i ti t l d o f b o th a d ynam i c rou ti ng pro t oco l an d static routes. ITE PC v4.0 Chapter 1 3 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public The Evolution of Dynamic Routing Protocols  One of the earliest routing protocols was Routing Information Protocol (RIP). RIP h l d i t i RIP 2 H – RIP h as evo l ve d i n t o a newer vers i on RIP v 2 . H owever, –The newer version of RIP still does not scale to larger network implementations.  To address the needs of larger networks, two advanced routing protocols were developed: Open Shortest Path First (OSPF) and Intermediate System-to- It dit S t (IS IS) I n t erme di a t e S ys t em (IS - IS) .  Cisco developed Interior Gateway Routing Protocol (IGRP) and Enhanced IGRP (EIGRP), which also scales well in larger network implementations.  Additionally there was the need to interconnect different internetworks and provide  Additionally , there was the need to interconnect different internetworks and provide routing among them. Border Gateway Routing (BGP) protocol is now used between ISPs as well as between ISPs and their larger private clients to exchange routing information.  With the advent of numerous consumer devices using IP the IPv4 addressing space  With the advent of numerous consumer devices using IP , the IPv4 addressing space is nearly exhausted. Thus IPv6 has emerged. To support the communication based on IPv6, newer versions of the IP routing protocols have been developed (see the IPv6 row in the table). ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Dynamic Routing Protocols  Function(s) of Dynamic Routing Protocols: -Dynamically share information between routers. -Automatically update routing table when topology changes. - Determine best path to a destination Determine best path to a destination . –Compared to static routing, dynamic routing protocols require less administrative overhead. • However, the expense of using dynamic routing protocols is dedicating part of a router ' s However, the expense of using dynamic routing protocols is dedicating part of a router s resources for protocol operation including CPU time and network link bandwidth. – One of the primary benefits to using a dynamic routing protocol is that routers exchange routing information whenever there is a topology change. This exchange ll t t t ti ll l b t t k d l t fi d lt t a ll ows rou t ers t o au t oma ti ca ll y l earn a b ou t new ne t wor k s an d a l so t o fi n d a lt erna t e paths when there is a link failure to a current network. ITE PC v4.0 Chapter 1 5 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Dynamic Routing Protocols  D esp it e th e be n e fit s o f dy n a mi c r ou tin g, s t a ti c r ou tin g s till esp e e be e s o dy a c ou g, s a c ou g s has its place.  There are times when static routing is more appropriate and There are times when static routing is more appropriate and other times when dynamic routing is the better choice.  More often than not you will find a combination of both More often than not , you will find a combination of both types of routing in any network that has a moderate level of complexity. ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Dynamic Routing Protocols  A routin g p rotocol gp –is a set of processes, algorithms, and messages that are used to exchange routing information and populate the routing table with the routin g p rotocol's choice of best p aths gp p  The purpose of a dynamic routing protocol is to: -Discover remote networks -Maintaining up-to-date routing information -Choosing the best path to destination networks Abilit t fi d b t th if th t th i l il bl - Abilit y t o fi n d a new b es t pa th if th e curren t pa th i s no l onger ava il a bl e ITE PC v4.0 Chapter 1 7 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Dynamic Routing Protocols Dynamic Routing Protocols  Components of a routing protocol – Data structures Data structures •Some routing protocols use tables and/or databases for its operations. This information is kept in RAM Al ith – Al gor ith m •Algorithm is a finite list of steps used in accomplishing a task • Algorithms are used for facilitating routing information and best path Algorithms are used for facilitating routing information and best path determination –Routing protocol messages Th f di i i hb d hf • Th ese are messages f or di scover i ng ne i g hb ors an d exc h ange o f routing information , and other tasks to learn and maintain accurate information about the network. ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Dynamic Routing Protocol Operation Dynamic Routing Protocol Operation  All routing protocols have the same purpose - to learn about remote networks and to quickly adapt whenever there is a change in the topology.  The method that a routing protocol uses to accomplish this depends upon the algorithm it uses and the operational characteristics of that protocol.  In general the operations of a dynamic routing protocol can be described as  In general , the operations of a dynamic routing protocol can be described as follows: –The router sends and receives routing messages on its interfaces. – The router shares routing messages and routing information with other routers that are using the same routing protocol. –Routers exchange routing information to learn about remote networks. – When a router detects a topology change the routing protocol can advertise this change to other routers. ITE PC v4.0 Chapter 1 9 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public Dynamic Routing Protocols  Advantages of static routing It b k lti l  Advantages of dynamic routing - It can b ac k up mu lti p l e interfaces/networks on a router -Minimal CPU processing Easier for administrator to -Administrator has less work maintaining the configuration when adding or deleting networks. - Easier for administrator to understand -Easy to configure - No extra resources are needed -Protocols automatically react to the topology changes. -Confi g uration is less erro r -prone. No extra resources are needed -More secure  Disadvantages of static routing g -More scalable, growing the network usually does not present a problem  Disadvantages of dynamic routing -Network changes require manual reconfiguration -Configuration and maintenance is time - consuming  Disadvantages of dynamic routing -Router resources are used (CPU cycles, memory and link bandwidth). time consuming -Does not scale well in large topologies -Confi g uration is erro r - p rone , -More administrator knowledge is required for configuration, verification, and troubleshooting. ITE PC v4.0 Chapter 1 10 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public g p, especially in large networks [...]... n is the number specified by the variance command Example: E-C-A: 20 * 2 = 40 Therefore, E-C-A and E-B-A will be used for load balancing router eigrp 1 network x.x.x.x variance 2 http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009 437 d.shtml ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 31 Administrative Distance of a Route In fact, a router might... Routing Protocols ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 11 Classifying Routing Protocols Dynamic routing protocols are grouped according to y gp g p g characteristics Examples include: -RIP -IGRP IGRP -EIGRP -OSPF OSPF -IS-IS BGP -BGP Autonomous System is a group of routers under the control of a single authority g y ITE PC v4.0 Chapter 1 © 2007 Cisco Systems,... interfaces listed in the routing table –per-packet load balancing •( Process Switching) –per-destination load balancing •(Fast Switching) Router(config-if)# ip route-cache ping 10.0.0.2 ITE PC v4.0 Chapter 1 ping 10.0.0.1 Router(config-if)#no ip route-cache ping 10.0.0.2 © 2007 Cisco Systems, Inc All rights reserved ping 10.0.0.1 Cisco Public 28 Load balancing with RIP per-packet load balancing debug ip packet... protocol developed by Cisco –OSPF OSPF •A link-state interior routing protocol –IS-IS •A link-state interior routing protocol –BGP •A path vector exterior routing p p g protocol ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 13 Classifying Routing Protocols An autonomous system (AS) - otherwise known as a routing domain - is a collection of routers under a common administration... ( ), g , , RIB: Router(config-if)#no ip route-cache http://www.cisco.com/en/US/products/ps57 63/ products_configuration_guide _chapter0 9186a00802a1fae.html#wp1045020 ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 29 Load balancing with RIP per-destination load balancing debug ip packet IP packet debugging i on k d b i is GAD# *Mar 1 19:14 :36 .006: IP: tableid=0, s=192.168.14.2... 19:14:51.958: IP: s=192.168. 13. 2 (Serial0/1), d=255.255.255.255, len 72, rcvd 2 *Mar 1 19:14:51.962: IP: s=192.168.15.2 (Serial0/0), d=255.255.255.255 Router(config-if)# ip route-cache RIB: http://www.cisco.com/en/US/products/ps57 63/ products_configuration_guide _chapter0 9186a00802a1fae.html#wp1045020 ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc All rights reserved Cisco Public 30 Unequal Cost Load Balancing... interface error count or previous link failures ITE PC v4.0 Chapter 1 OSPF RIP © 2007 Cisco Systems, Inc All rights reserved Cisco Public 24 Routing Protocols Metrics The Metric Field in the Routing Table Metric used for each routing protocol -RIP - hop count -IGRP & EIGRP - Bandwidth (used by default), Delay (used by default), Load, Reliability -IS-IS & OSPF – Cost, Bandwidth (Cisco’s implementation) Refer... (Serial0/1), g=192.168. 13. 2, len 60, forward *Mar 1 19:10 :32 .218: IP: s=0.0.0.0 (FastEthernet0/0), d=255.255.255.255, len 604, rcvd 2 *Mar 1 19:10 :32 .654: IP: tableid=0, s=192.168.14.2 (FastEthernet0/0), d=192.168.16.2 (Serial0/0), routed via RIB *Mar 1 19:10 :32 .654: IP: s=192.168.14.2 (FastEthernet0/0), d=192.168.16.2 (Serial0/0), g=192.168.15.2, len 60, forward *Mar 1 19:10 :33 .654: IP: tableid=0, s=192.168.14.2... routed via RIB *Mar 1 19:10 :33 .654: IP: s=192.168.14.2 (FastEthernet0/0), d=192.168.16.2 (Serial0/1), g=192.168. 13. 2, len 60, forward *Mar 1 19:10 :34 .654: IP: tableid=0, s=192.168.14.2 (FastEthernet0/0), d=192.168.16.2 (Serial0/0), routed via RIB *Mar 1 19:10 :34 .654: IP: s=192.168.14.2 (FastEthernet0/0), d=192.168.16.2 (Serial0/0), g=192.168.15.2, len 60, forward *Mar 1 19:10 :35 .654: IP: tableid=0, s=192.168.14.2... routed via RIB *Mar 1 19:10 :35 .654: IP: s=192.168.14.2 (FastEthernet0/0), d=192.168.16.2 (Serial0/1), g=192.168. 13. 2, len 60, forward *Mar 1 19:10 :35 .974: IP: s=192.168. 13. 1 (local), d=255.255.255.255 (Serial0/1), len 72, sending broad/multicast *Mar 1 19:10 :36 .654: IP: tableid=0, s=192.168.14.2 (FastEthernet0/0), d=192.168.16.2 (Serial0/0), routed via RIB *Mar 1 19:10 :36 .654: IP: s=192.168.14.2 (FastEthernet0/0), . g characteristics. Examples include: -RIP IGRP - IGRP -EIGRP OSPF - OSPF -IS-IS - BGP BGP  Autonomous System is a group of routers under the control of a sin g le authorit y . ITE PC v4.0 Chapter 1 12 © 2007. understand -Easy to configure - No extra resources are needed -Protocols automatically react to the topology changes. -Confi g uration is less erro r -prone. No extra resources are needed -More. protocol is to: -Discover remote networks -Maintaining up-to-date routing information -Choosing the best path to destination networks Abilit t fi d b t th if th t th i l il bl - Abilit y t o