Giao thức định tuyến - Chapter 5

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Describe the functions, c a ac e s cs, a d ope a o esc be e u c o s, characteristics, and operation of the RIPv1 protocol. Configure a device for using RIPv1. Verify proper RIPv1 operation. Describe how RIPv1 performs automatic f summarization. Configure, verify, and troubleshoot default routes propagated in a routed network implementing RIPv1.

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Nội dung Text: Giao thức định tuyến - Chapter 5

RIP version 1 Routing Protocols and Concepts – Chapter 5 ITE PC v4.0 1 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Objectives Describe the functions, characteristics, and operation esc ope of the RIPv1 protocol. Configure device for using RIPv1. Configure a device for using RIPv1. Verify proper RIPv1 operation. Describe how RIPv1 performs automatic summarization. Configure, verify, and troubleshoot default routes propagated in a routed network implementing RIPv1. Use recommended techniques to solve problems related to RIPv1 ITE PC v4.0 2 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIP Historical Impact RIP evolved from an earlier protocol developed at Xerox, called Gateway Information Protocol (GWINFO). With the development of Xerox Network System (XNS) GWINFO evolved into System (XNS), GWINFO evolved into RIP. It later gained popularity because it was implemented in the Berkeley Software Distribution (BSD) as a daemon named routed (pronounced "route-dee", not "rout-ed"). Recognizing the need for standardization the need for standardization of the protocol, Charles Hedrick wrote RFC 1058 in 1988, in which he documented the existing protocol and specified some improvements specified some improvements. Since then, RIP has been improved with IPv6 form of RIP called RIPv2 in 1994 and with RIPng in 1997. RIPng (next generation) is RIPng (next generation) is now available ITE PC v4.0 3 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIPv1 RIP Characteristics –A classful, Distance Vector (DV) routing protocol (DV) routing protocol –Metric = hop count –Routes with a hop count > 15 are unreachable –Updates are broadcast every 30 seconds 30 seconds –The data portion of a RIP message is encapsulated into a UDP segment, with both UDP segment with both source and destination port numbers set to 520. ITE PC v4.0 4 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIPv1 RIPv1 RIP Message Format RIP header divided into fields RIP header - divided into 3 fields –Command field •REQUEST (1)- Request either a partial or full table update from another RIP router. •RESPONSE (2) - A response to a request. –Version field •1 or 2 or –Must be zero •Must be zero" fields provide room for future expansion of the protocol. Route Entry - composed of 3 fields –Address family identifier •CLNS, IPX, IP etc. –IP address –Metric ITE PC v4.0 5 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIPv1 RIP Operation –RIP uses 2 message types: Request message -This is sent out on startup by each RIP is sent out on startup by each RIP enabled interface -Requests all RIP enabled neighbors to send all RIP enabled neighbors to send routing table Response message Response message -Message sent to requesting router containing routing table containing routing table ITE PC v4.0 6 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIP RIPv1 IP addresses initially divided into classes -Class A -Class B -Class C RIP is a classful routing protocol -Does not send subnet masks in routing updates ITE PC v4.0 7 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Common RIP configuration issues RIP and IGRP: Classful network statements only IOS will take subnetted networks but will translate it into the classful network for the running-config. ITE PC v4.0 8 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
RIPv1 RIPv1 Administrative Distance –RIP’s default administrative distance is 120 ITE PC v4.0 9 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Basic RIPv1 Configuration A typical topology suitable for typical topology suitable for use by RIPv1 includes: -Three router set up router set up -No PCs attached to LANs -Use of 5 different IP diff IP subnets ITE PC v4.0 10 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Basic RIPv1 Configuration RIP Router RIP Command Router RIP Command –To enable RIP enter: -Router rip at the global configuration prompt rip the global configuration prompt -Prompt will look like R1(config-router)# ITE PC v4.0 11 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Basic RIPv1 Configuration Basic RIPv1 Configuration Specifying Networks –Use the network command to: -Enable RIP on all interfaces that belong to this network -Advertise this network in RIP updates updates sent to other routers every 30 seconds ITE PC v4.0 12 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Verification and Troubleshooting Show ip Route To verify and verify and troubleshoot routing -Use the following commands: -show ip route -show ip protocols ip protocols -debug ip rip ITE PC v4.0 13 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Verification and Troubleshooting show ip protocols ip protocols command -Displays routing protocol configured on router POP QUIZ: QUIZ: What is the different between the output of the command “show ip route” and “show ip protocol”? ITE PC v4.0 14 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Verification and Troubleshooting Verification and Troubleshooting Debug ip rip command -Used to display RIP routing updates as they are to display RIP routing updates as they are happening ITE PC v4.0 15 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Verification and Troubleshooting Passive interface command -Used to prevent a router from sending updates through to prevent router from sending updates through an interface -Example: Router(config-router)#passive-interface interface-type interface-number ITE PC v4.0 16 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Verification and Troubleshooting Passive interfaces Passive interfaces ITE PC v4.0 17 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Preventing routing updates through an interface Route filtering works by regulating the routes that are entered into or advertised out of a route table. Lab: As a result, a route filter influences which routes the router advertises to its neighbors. On the other hand, routers running link the other hand routers running link state protocols determine routes based on information in the link-state database. Route filters have no effect on link-state advertisements or the link advertisements or the link-state database. database (Tony) Route filtering could have negative effect on the link-state routing protocol. Using the passive interface command the passive interface can prevent routers from sending routing updates through a router interface, but the router continues to listen and use routing updates from that neighbor routing updates from that neighbor. Keeping routing update messages from being sent through a router interface prevents other systems on that network from learning about routes dynamically from learning about routes dynamically. ITE PC v4.0 18 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Preventing routing updates Preventing routing updates It will break the rip update 1 through an interface Again, this is only half the this is only half the story. When you use “passive you use “passive interface” on a distance vector routing protocol, you need to complement it with You can use the “ip route” “ip route” command. command to send route update 2 back to establish the 2 way communication ITE PC v4.0 19 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Automatic Summarization Automatic Summarization Modified Topology The original scenario has been The original scenario has been 172.30.3.0 modified such that: Three classful networks are used: 172.30.0.0/16 172.30.2.0 192.168.4.0/24 172.30.1.0 192.168.5.0/24 The 172.30.0.0/16 network is subnetted into three subnets: 172.30.1.0/24 172.30.2.0/24 172.30.3.0/24 The following devices are part of the 172.30.0.0/16 classful network address: All interfaces on R1 S0/0/0 and Fa0/0 on R2 ITE PC v4.0 20 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public