Bài giảng môn Mạng máy tính - Chapter 5: Rip version 1

RIP characteristics include: – Classful, distance vector routing protocol – Metric is Hop Count – Does not support VLSM or discontiguous subnets – Updates every 30 seconds • Rip messages are encapsulated in a UDP segment with source and destination ports of 520

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Chapter 5: RIP version 1 CCNA Exploration version 4.0 Học viện mạng Bách Khoa - Website: www.bkacad.com 2 Objectives • Describe the functions, characteristics, and operation of the RIPv1 protocol. • 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 Học viện mạng Bách Khoa - Website: www.bkacad.com 3 RIPv1: Distance Vector, Classful Routing Protocol Học viện mạng Bách Khoa - Website: www.bkacad.com 4 RIP History Học viện mạng Bách Khoa - Website: www.bkacad.com 5 RIP Characteristics 1. A classful, Distance Vector (DV) routing protocol 2.Metric = hop count 3. Routes with a hop count > 15 are unreachable (considers a metric of 16 as infinity ) 4. Updates are broadcast every 30 seconds 5. Calculates metrics using the Bellman Ford algorithm Học viện mạng Bách Khoa - Website: www.bkacad.com 6 RIPv1 Message 5.1.2.1 Học viện mạng Bách Khoa - Website: www.bkacad.com 7 RIP Message Format 5.1.2.2 Why are there so many fields set to zero? Học viện mạng Bách Khoa - Website: www.bkacad.com 8 RIP Message Format • RIP header - divided into 3 fields 1. Command field 2. Version field 3. Must be zero • Route Entry - composed of 3 fields 1. Address family identifier 2. IP address 3. Metric Học viện mạng Bách Khoa - Website: www.bkacad.com 9 RIP Operation 1.Request message –Each RIP-configured interface sends out a request message on startup, requesting that all RIP neighbors send their complete routing tables. 2.Response message –A response message is sent back by RIP- enabled neighbors. 5.1.3.1 Học viện mạng Bách Khoa - Website: www.bkacad.com 10 RIPv1 a) b) c) Triggered update Học viện mạng Bách Khoa - Website: www.bkacad.com 11 RIPv1 Học viện mạng Bách Khoa - Website: www.bkacad.com 12 RIPv1 • RIP is a classful routing protocol 1. Does not send subnet masks in routing updates 2. When update routing information, using: 1. The subnet mask configured on a local interface 2. or applies the default subnet mask based on the address class. 3. RIPv1 networks cannot be discontiguous nor can they implement VLSM. Học viện mạng Bách Khoa - Website: www.bkacad.com 13 Administrative Distance 5.1.4 Học viện mạng Bách Khoa - Website: www.bkacad.com 14 Administrative Distance • Default AD=120. •When compared to other interior gateway protocols, RIP is the least-preferred routing protocol. • IS-IS, OSPF, IGRP, and EIGRP all have lower default AD values. Học viện mạng Bách Khoa - Website: www.bkacad.com 15 Basic RIPv1 Configuration Học viện mạng Bách Khoa - Website: www.bkacad.com 16 Basic RIPv1 Configuration • Router(config)# router rip • Router(config-router)# network A.B.C.D 5.2.2 Basic RIPv1 Configuration R1(config)#router rip (config-router)#network 192.168.1.0 (config-router)#network 192.168.2.0 (config-router)#network 172.16.1.0 R2(config)#router rip (config-router)#network 192.168.3.0 (config-router)#network 192.168.2.0 (config-router)#network 172.16.2.0 Học viện mạng Bách Khoa - Website: www.bkacad.com 17 Học viện mạng Bách Khoa - Website: www.bkacad.com 18 Specifying Networks Học viện mạng Bách Khoa - Website: www.bkacad.com 19 Specifying Networks • Router(config-router)#network directly-connected-classful- network-address –Enables RIP on all interfaces that belong to a specific network. Associated interfaces will now both send and receive RIP updates. –Advertises the specified network in RIP routing updates sent to other routers every 30 seconds. Specifying Networks • Typing interface IP addresses as the following: – Router(config-if)#router rip – Router(config-router)#version 1 – Router(config-router)#network 1.1.1.1 – Router(config-router)#network 1.1.1.2 – Router(config-router)#network 3.3.3.2 • show running-config router rip network 1.0.0.0 network 3.0.0.0 Học viện mạng Bách Khoa - Website: www.bkacad.com 20 Học viện mạng Bách Khoa - Website: www.bkacad.com 21 Verification and Troubleshooting Học viện mạng Bách Khoa - Website: www.bkacad.com 22 show ip route Học viện mạng Bách Khoa - Website: www.bkacad.com 23 show ip route Học viện mạng Bách Khoa - Website: www.bkacad.com 24 show ip protocols Học viện mạng Bách Khoa - Website: www.bkacad.com 25 show ip protocols • RIP routing is configured • The correct interfaces send and receive RIP updates • The router advertises the correct networks • RIP neighbors are sending updates • Animation 5.3.2 Học viện mạng Bách Khoa - Website: www.bkacad.com 26 • Animation 5.3.3 debug ip rip Học viện mạng Bách Khoa - Website: www.bkacad.com 27 Passive interfaces • To prevent a router from sending updates through an interface. • Example: Router(config-router)#passive-interface FastEthernet 0/0 Học viện mạng Bách Khoa - Website: www.bkacad.com 28 Passive interfaces Học viện mạng Bách Khoa - Website: www.bkacad.com 29 Remove RIP • To remove the RIP routing process use the following command Router(config)#no router rip • To check the configuration use the following command Router#show running-config Học viện mạng Bách Khoa - Website: www.bkacad.com 30 Automatic Summarization Học viện mạng Bách Khoa - Website: www.bkacad.com 31 Automatic Summarization Học viện mạng Bách Khoa - Website: www.bkacad.com 32 Automatic Summarization • Boundary Routers • RIP automatically summarizes classful networks • Boundary routers summarize RIP subnets from one major network to another. Học viện mạng Bách Khoa - Website: www.bkacad.com 33 Automatic Summarization Automatic Summarization Major network = Classful network Học viện mạng Bách Khoa - Website: www.bkacad.com 34 Học viện mạng Bách Khoa - Website: www.bkacad.com 35 Processing RIP Updates • 2 rules govern RIPv1 updates: 1. If a routing update and the interface it’s received on belong to the same network then the subnet mask of the interface is applied to the network in the routing update 2. If a routing update and the interface it’s received on belong to a different network then the classful subnet mask of the network is applied to the network in the routing update. Router 1 Router 2 12.1.0.0/16 10.1.0.0/16 10.3.0.0/16 .1.2 .1 .2 .2 10.2.0.0/16 Send update Same major Summarize to major Same mask Advertise update N N Y Y Receive update Same major Subnet in RT Install route using receiving mask interface N N Y Y Install major route + 10.1.0.0/16 is same major net as sourcing of update 10.2.0.0/16 ? -Yes: are they have same subnet mask? - Yes : advertise the subnet 10.1.0.0/16 + 12.1.0.0 /16 is same major net as sourcing of update 10.2.0.0/16 ? - No: Summarize to 12.0.0.0 to advertise + Is 12.0.0.0 same major net as receiving interface 10.2.0.0/16 ? -No: do any of this major net exist in RT? - No : Router 2 apply major net 12.0.0.0/8 to RT + 10.1.0.0 /16 same major net as receiving interface 10.2.0.0/16 ? - Yes:Router 2 apply mask of receiving interface (/16) to subnet Router 1 Router 2 10.1.0.0/16 10.2.0.0/16 .1 .2 .1.2 172.16.0.0/16 + 10.1.0.0/16 is same major net as sourcing of update 172.16.0.0/16 ? -No:Summarize to 10.0.0.0 to advertise Using debug ip rip to see update + Is 10.0.0.0 same major net as receiving interface 172.16.0.0/16 ? -No: do any of this major net exist in RT known from interfaces other than that which received the update? - Yes : Router 2 ignore the update Discontiguous network Static route: ip route network [ mask ] { address | interface } [ distance ] [ permanent ] On Router 1: ip route 10.2.0.0 255.255.0.0 172.16.0.1 On Router 2 ip route 10.1.0.0 255.255.0.0 172.16.0.2 Học viện mạng Bách Khoa - Website: www.bkacad.com 38 Processing RIP Updates Học viện mạng Bách Khoa - Website: www.bkacad.com 39 Sending RIP Updates Học viện mạng Bách Khoa - Website: www.bkacad.com 40 Advantages of Automatic Summarization Học viện mạng Bách Khoa - Website: www.bkacad.com 41 Advantages of Automatic Summarization • RIP uses automatic summarization to reduce the size of a routing table. • Single routes are used to represent multiple routes which results in faster lookup in the routing table. Học viện mạng Bách Khoa - Website: www.bkacad.com 42 Disadvantages of Automatic Summarization • Does not support discontiguous networks Học viện mạng Bách Khoa - Website: www.bkacad.com 43 Disadvantages of Automatic Summarization • Discontiguous Topologies do not converge with RIPv1 • A router will only advertise major network addresses out interfaces that do not belong to the advertised route. Học viện mạng Bách Khoa - Website: www.bkacad.com 44 Default Route and RIPv1 Học viện mạng Bách Khoa - Website: www.bkacad.com 45 Default Route and RIPv1 Học viện mạng Bách Khoa - Website: www.bkacad.com 46 Default Route and RIPv1 • Packets that are not defined specifically in a routing table will go to the specified interface for the default route • Example: Customer routers use default routes to connect to an ISP router. • Router(config)# ip route 0.0.0.0 0.0.0.0 {exit-interface | next-hop IP address} Học viện mạng Bách Khoa - Website: www.bkacad.com 47 Default Route and RIPv1 Học viện mạng Bách Khoa - Website: www.bkacad.com 48 Default Route and RIPv1 • Propagating the Default Route in RIPv1: • Router(config-router)# default-information originate • This command is used to specify that the router is to originate default information, by propagating the static default route in RIP update. Học viện mạng Bách Khoa - Website: www.bkacad.com 49 Default Route and RIPv1 Gateway of last resort Học viện mạng Bách Khoa - Website: www.bkacad.com 50 Propogate the static default route Gate(config)# Ip route 0.0.0.0 0.0.0.0 serial0/1 Gate(config)#router rip default-information originate Or Gate(config)#router rip redistribute static Học viện mạng Bách Khoa - Website: www.bkacad.com 51 Other command • Router# clear ip route * • Delete all route entries in RT. Do not effect to the directly connected routes. Học viện mạng Bách Khoa - Website: www.bkacad.com 52 Other command Học viện mạng Bách Khoa - Website: www.bkacad.com 53 Other command Học viện mạng Bách Khoa - Website: www.bkacad.com 54 Q/A • All routers are configured with valid interface addresses in the indicated networks and are running RIPv1. The network is converged. Which routes are present in the routing tables? Học viện mạng Bách Khoa - Website: www.bkacad.com 55 Q/A • The Ethernet interface on Router2 goes down and the administrator notices that the route is still valid in the routing table of Router1. How much longer will it take for Router1 to mark the route invalid by setting the metric to 16? Học viện mạng Bách Khoa - Website: www.bkacad.com 56 Học viện mạng Bách Khoa - Website: www.bkacad.com 57 Labs 1. Basic RIP Configuration 2. Challenge RIP Configuration 3. RIP Troubleshooting Học viện mạng Bách Khoa - Website: www.bkacad.com 58 Summary • RIP characteristics include: – Classful, distance vector routing protocol – Metric is Hop Count – Does not support VLSM or discontiguous subnets – Updates every 30 seconds • Rip messages are encapsulated in a UDP segment with source and destination ports of 520 Học viện mạng Bách Khoa - Website: www.bkacad.com 59 Summary: Commands used by RIP Command Command’s purpose Rtr(config)#router rip Enables RIP routing process Rtr(config-router)#network Associates a network with a RIP routing process Rtr#debug ip rip used to view real time RIP routing updates Rtr(config-router)#passive-interface fa0/0 Prevent RIP updates from going out an interface Rtr(config-router)#default-information originate Used by RIP to propagate default routes Rtr#show ip protocols Used to display timers used by RIP Học viện mạng Bách Khoa - Website: www.bkacad.com 60 • R1(config)#router rip • R1(config-router)#version 1 • R1(config-router)#network 192.168.1.0 • R1(config-router)#network 192.168.2.0 • R2(config)#router rip • R2(config-router)#version 1 • R2(config-router)#network 192.168.3.0 • R2(config-router)#network 192.168.2.0 Học viện mạng Bách Khoa - Website: www.bkacad.com 61 • R2(config)#router rip • R2(config-router)#version 1 • R2(config-router)#network 192.168.3.0 • R2(config-router)#network 192.168.2.0 Học viện mạng Bách Khoa - Website: www.bkacad.com 62

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