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Chapter 5 RIP version 1

TECI 185 Routing Protocols and Concepts Jack Yon Western Colorado Community College jyon@mesastate.edu Last Updated: 3/24/2009. Chapter 5 RIP version 1. Topics. Automatic Summarization Modified Topology B Boundary Routers and Automatic Summarization Processing RIP Updates

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Chapter 5 RIP version 1

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  1. TECI 185 Routing Protocols and Concepts Jack Yon Western Colorado Community College jyon@mesastate.edu Last Updated: 3/24/2009 Chapter 5RIP version 1

  2. Topics • Automatic Summarization • Modified Topology B • Boundary Routers and Automatic Summarization • Processing RIP Updates • Sending RIP Updates • Advantages and Disadvantages of Automatic Summarization • Default Route and RIPv1 • Modified Topology C • Propagating the Default Route in RIPv1 • RIPv1: Distance Vector, Classful Routing Protocol • Background and Perspective • RIPv1 Characteristics and Message Format • RIP Operation • Basic RIPv1 Configuration • RIPv1 Scenario A • Enable RIP: router rip Command • Specifying Networks • Verification and Troubleshooting • Verifying RIP: show ip route • Verifying RIP: show ip protocols • Verifying RIP: debu ip rip • Passive Interfaces

  3. RIPv1 • Download Packet Tracer Topology: cis82-RIPv1-A-student.pkt

  4. Background and Perspective RIPv1 Characteristics and Message Format RIP Operation RIPv1: A Distance Vector, Classful Routing Protocol

  5. RIPv1: Distance Vector, Classful Routing Protocol • Why learn RIP? • Still in use today. • Help understand fundamental concepts and comparisons of protocols • Classful (RIPv1) vs classless (RIPv2)

  6. Background and Perspective • RIP is not a protocol “on the way out.” • In fact, an IPv6 form of RIP called RIPng (next generation) is now available..

  7. Background and Perspective • Charles Hedrick wrote RFC 1058 in 1988, in which he documented the existing protocol and specified some improvements. • RFC 1058 can be found at http://www.ietf.org/rfc/rfc1058.txt

  8. RIPv1 Characteristics and Message Format • RIP characteristics: • Distance Vector or Link State? • Distance vector routing protocol. • Metric? • Hop count • Maximum Hop count? • Greater than 15 are considered unreachable. • Routing table updates are broadcasted every…? • 30 seconds. (RIPv2 uses multicasts)

  9. RIPv1 Characteristics and Message Format

  10. RIPv1 Characteristics and Message Format

  11. IP Address Classes and Classful Routing No subnet mask • RIPv1: • Classful routing protocol. • Does not send subnet mask in update.

  12. IP Address Classes and Classful Routing Routing Table ? Network-add/mask RIP Update network-add /16 • R2 receives an RIP update with a network address. • R2 adds the network address and mask to the routing table. • A router either uses the subnet mask: (discussed later) • Local interface or • Default classful subnet mask • Because of this limitation, RIPv1 networks cannot be discontiguous, nor can they implement VLSM.

  13. RIPv1 Scenario A Enable RIP: router rip Command Specifying Networks Basic RIPv1 Configuration

  14. RIPv1 Scenario A • RIPv1 is a classful or classless routing protocol? • Classful • How many classful networks are there and of what class? • 5 Class C network addresses. • We will see that the class of the network is used by RIPv1 to determine the subnet mask.

  15. Enabling RIP: router rip Command R1# conf t Enter configuration commands, one per line. End with CNTL/Z. R1(config)# router ? bgp Border Gateway Protocol (BGP) egp Exterior Gateway Protocol (EGP) eigrp Enhanced Interior Gateway Routing Protocol (EIGRP) igrp Interior Gateway Routing Protocol (IGRP) isis ISO IS-IS iso-igrp IGRP for OSI networks mobile Mobile routes odr On Demand stub Routes ospf Open Shortest Path First (OSPF) rip Routing Information Protocol (RIP) R1(config)# router rip R1(config-router)# • What routing protocols does this router support? (PT is limited) • Configure RIP…

  16. Enabling RIP: router rip Command R1# conf t R1(config)# router rip R1(config-router)# network 192.168.1.0 R1(config-router)# network 192.168.2.0 R1(config-router)# exit R1(config)# norouter rip • no router rip • To remove the RIP routing process from a device • Stops the RIP process • Erases all existing RIP configuration commands.

  17. Specifying Networks Router(config-router)# networkdirectly-connected-classful-network-address • To enable RIP routing for a network, use the networkcommand in router configuration mode • Enter the classful network address for each directly connected network.

  18. Specifying Networks R1(config)# router rip R1(config-router)#network 192.168.1.0 R1(config-router)#network 192.168.2.0 RIP Update • The network command performs the following functions: • 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 (no mask).

  19. Specifying Networks Only directly connected classful network addresses! R1(config)# router rip R1(config-router)# network 192.168.1.0 R1(config-router)# network 192.168.2.0 R2(config)# router rip R2(config-router)# network 192.168.2.0 R2(config-router)# network 192.168.3.0 R2(config-router)# network 192.168.4.0 R3(config)# router rip R3(config-router)# network 192.168.4.0 R3(config-router)# network 192.168.5.0 • Configure RIP for all three routers • What happens if you enter a subnet or host IP address? (Try it) • IOS automatically converts it to a classful network address. • For example, if you enter the command network 192.168.1.32, the router will convert it to network 192.168.1.0.

  20. Only directly connected classful network addresses!

  21. Administrative Distance R3# show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, <some output omitted> * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is not set R 192.168.1.0/24 [120/2] via 192.168.4.2, 00:00:13, Serial0/0/1 R 192.168.2.0/24 [120/1] via 192.168.4.2, 00:00:25, Serial0/0/1 R 192.168.3.0/24 [120/1] via 192.168.4.2, 00:00:25, Serial0/0/1 C 192.168.4.0/24 is directly connected, Serial0/0/1 C 192.168.5.0/24 is directly connected, FastEthernet0/0 R3# R = RIP • What is the administrative distance of a network route learned via RIP? • 120

  22. Administrative Distance R3# show ip protocols <output omitted> Routing Protocol is “rip” Routing Information Sources: Gateway Distance Last Update 192.168.6.2 120 00:00:10 Distance: (default is 120) • Where is the administrative distance displayed using this command?

  23. Verifying RIP: show ip route Verifying RIP: show ip protocols Verifying RIP: debu ip rip Passive Interfaces Verification and Troubleshooting

  24. Verifying RIP: show ip route on all three routers… R1# show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, <output omitted> Gateway of last resort is not set R 192.168.4.0/24 [120/1] via 192.168.2.2, 00:00:02, Serial0/0/0 R 192.168.5.0/24 [120/2] via 192.168.2.2, 00:00:02, Serial0/0/0 C 192.168.1.0/24 is directly connected, FastEthernet0/0 C 192.168.2.0/24 is directly connected, Serial0/0/0 R 192.168.3.0/24 [120/1] via 192.168.2.2, 00:00:02, Serial0/0/0 • The routing table, includes what kind of routes? • Directly connected networks • Static routes • Dynamic routes • Why might a RIP route not be immediately displayed in the routing table? • Networks will take some time to converge.

  25. Verifying RIP: show ip route Command R2# show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, <output omitted> Gateway of last resort is not set C 192.168.4.0/24 is directly connected, Serial0/0/1 R 192.168.5.0/24 [120/1] via 192.168.4.1, 00:00:12, Serial0/0/1 R 192.168.1.0/24 [120/1] via 192.168.2.1, 00:00:24, Serial0/0/0 C 192.168.2.0/24 is directly connected, Serial0/0/0 C 192.168.3.0/24 is directly connected, FastEthernet0/0 • Using R2, which routes do you expect to see in our scenario? • Directly connected networks of R2 • RIP routes for remote networks • What routes do you expect not to see? • Networks not in our scenario – not configured with network statements on the routers. • Static default route

  26. Verifying RIP: show ip route Command R3# show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, <output omitted> Gateway of last resort is not set C 192.168.4.0/24 is directly connected, Serial0/0/1 C 192.168.5.0/24 is directly connected, FastEthernet0/0 R 192.168.1.0/24 [120/2] via 192.168.4.2, 00:00:08, Serial0/0/1 R 192.168.2.0/24 [120/1] via 192.168.4.2, 00:00:08, Serial0/0/1 R 192.168.3.0/24 [120/1] via 192.168.4.2, 00:00:08, Serial0/0/1

  27. Verifying RIP: show ip route Command R1# show ip route <output omitted> R 192.168.5.0/24 [120/2] via 192.168.2.2, 00:00:23, Serial0/0/0

  28. Examine and discuss the show ip protocols Command

  29. Verifying RIP: show ip protocols Command • Verifies that RIP routing is configured and running on Router R2 • At least one active interface with an associated network command is needed before RIP routing will start.

  30. Verifying RIP: show ip protocols Command • These are the timers that show when the next round of updates will be sent out from this router—23 seconds from now, in the example.

  31. Verifying RIP: show ip protocols Command • This information relates to filtering updates and redistributing routes, if configured on this router. • Filtering and redistribution are both CCNP-level topics.

  32. Verifying RIP: show ip protocols Command • Information about which RIP version is currently configured and which interfaces are participating in RIP updates.

  33. Verifying RIP: show ip protocols Command • Router R2 is currently summarizing at the classful network boundary • By default, will use up to four equal-cost routes to load-balance. • Automatic summarization is discussed later in this chapter.

  34. Verifying RIP: show ip protocols Command • Classful networks configured with the network command are listed next. • These are the networks that R2 will include in its RIP updates. (with other learned routes)

  35. Verifying RIP: show ip protocols Command • RIP neighbors • Gateway: Next-hop IP address of the neighbor that is sending R2 updates. • Distance is the AD that R2 uses for updates sent by this neighbor. • Last Update is the seconds since the last update was received from this neighbor.

  36. Use debug ip rip to view RIP updates that are sent and received… • The debug command is a useful tool to help diagnose and resolve networking problems, providing real-time, continuous information.

  37. RIP: received v1 update from 192.168.2.1 on Serial0/0/0 192.168.1.0 in 1 hops • Assuming all routers have converged, why were no other routes from R1’s routing table sent to R2? • Split horizon rule. • R1 is will not advertise networks back to R2 that were learned from R2.

  38. RIP: received v1 update from 192.168.4.1 on Serial0/0/1 192.168.5.0 in 1 hops

  39. RIP: sending v1 update to 255.255.255.255 via FastEthernet0/0 (192.168.3.1) RIP: build update entries network 192.168.1.0 metric 2 network 192.168.2.0 metric 1 network 192.168.4.0 metric 1 network 192.168.5.0 metric 2 Learned via RIP from R1 Learned via RIP from R3 Directly Connected

  40. RIP: sending v1 update to 255.255.255.255 via Serial0/0/1 (192.168.4.2) RIP: build update entries network 192.168.1.0 metric 2 network 192.168.2.0 metric 1 network 192.168.3.0 metric 1 Directly Connected Learned via RIP from R1

  41. RIP: sending v1 update to 255.255.255.255 via Serial0/0/0 (192.168.2.2) RIP: build update entries network 192.168.3.0 metric 1 network 192.168.4.0 metric 1 network 192.168.5.0 metric 2 R2# undebug all All possible debugging has been turned off Directly Connected Learned via RIP from R3

  42. Passive Interfaces Got Router? • Does R2 need to send RIP updates out Fa 0/0? What are the disadvantages to this? • No, there is no RIP router or any router. • Bandwidth is wasted transporting unnecessary updates. • All devices on the LAN must process the RIPv1 update up to the transport layer. • Security risk (Authentication would is a better solution - later)

  43. Passive Interfaces Router(config-router)# passive-interface interface-type interface-number • What about using on R2: R2(Config-router)# no network 192.168.3.0 • R2 would not advertise this LAN as a route in updates sent to R1 and R3. • Correct solution is to use the passive-interfacecommand

  44. Passive Interfaces – Use it on R2… R2(config)# router rip R2(config-router)# passive-interface FastEthernet 0/0 X

  45. Passive Interfaces R2# show ip protocols <output omitted> Interface Send Recv Triggered RIP Key-chain Serial0/0/0 1 1 2 Serial0/0/1 1 1 2 Automatic network summarization is in effect Routing for Networks: 192.168.2.0 192.168.3.0 192.168.4.0 Passive Interface(s): FastEthernet0/0 Routing Information Sources: Gateway Distance Last Update 192.168.2.1 120 00:00:27 192.168.4.1 120 00:00:23 Distance: (default is 120) FastEthernet 0/0 no longer included LAN network still included in RIP updates that are sent FastEthernet 0/0 is a passive interface

  46. Modified Topology B Boundary Routers and Automatic Summarization Processing RIP Updates Sending RIP Updates Advantages and Disadvantages of Automatic Summarization Automatic Summarization

  47. Modified Topology: Scenario B 192.168.4.0/24 172.30.0.0/16 192.168.5.0/24 • Where is the separation of classful networks? • Summarizing several routes into a single route is known as route summarizationor route aggregation. • Fewer routes = smaller routing tables = faster lookups • Some routing protocols, such as RIP, automatically summarize routes on certain routers.

  48. Modified Topology: Scenario B 192.168.4.0/24 172.30.0.0/16 192.168.5.0/24 • What are the classful networks? • 172.30.0.0/16 • 192.168.4.0/24 • 192.168.5.0/24 • How is 172.30.0.0/16 network subnetted? • 172.30.1.0/24 • 172.30.2.0/24 • 172.30.3.0/24 • Is 192.168.4.0/24 subnetted? • 192.168.4.8/30.

  49. Configuration Changes for R1 R1(config)# interface fa0/0 R1(config-if)# ip address 172.30.1.1 255.255.255.0 R1(config-if)# interface S0/0/0 R1(config-if)# ip address 172.30.2.1 255.255.255.0 R1(config-if)# no router rip R1(config)# router rip R1(config-router)# network 172.30.1.0 R1(config-router)# network 172.30.2.0 R1(config-router)# passive-interface FastEthernet 0/0 R1(config-router)# end R1# show run <output omitted> ! router rip passive-interface FastEthernet0/0 network 172.30.0.0 ! <output omitted> IOS automatically corrects subnet entries to classful network address The no shutdown and clock rate commands are not needed because these commands are still configured from Scenario A.

  50. Configuration Changes for R2 R2(config)# interface S0/0/0 R2(config-if)# ip address 172.30.2.2 255.255.255.0 R2(config-if)# interface fa0/0 R2(config-if)# ip address 172.30.3.1 255.255.255.0 R2(config-if)# interface S0/0/1 R2(config-if)# ip address 192.168.4.9 255.255.255.252 R2(config-if)# no router rip R2(config)# router rip R2(config-router)# network 172.30.0.0 R2(config-router)# network 192.168.4.8 R2(config-router)# passive-interface FastEthernet 0/0 R2(config-router)# end R2# show run <output omitted> ! router rip passive-interface FastEthernet0/0 network 172.30.0.0 network 192.168.4.0 ! <output omitted> IOS automatically corrects subnet entries to classful network address

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