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RIP v1 and RIP v2

RIP v1 and RIP v2. Routing Protocol. Router. Switch. Router. Router. Router. Router. Switch. What is an optimal route ?. Learning Objectives:. Comparing RIP v1 and v2 Enable RIPv2 on a router. Advertise networks using RIPv2. Configure Passive Interfaces.

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RIP v1 and RIP v2

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  1. RIP v1 and RIP v2

  2. Routing Protocol Router Switch Router Router Router Router Switch What is an optimal route ?

  3. Learning Objectives: • Comparing RIP v1 and v2 • Enable RIPv2 on a router. • Advertise networks using RIPv2. • Configure Passive Interfaces. • Summarizing Routes with RIPv2. • Disable RIPv2 automatically summarizes • Verify RIPv2 configuration. • Count to infinity problem • Authentication using rip v2 • Triggered route • Offset list

  4. RIP: Routing Information Protocol • The easiest Interior Gateway Protocol to configure • Distance vector routing protocol that broadcast entire routing table to neighbor every 30 seconds • RIP use hop count(the number of routers a packet must pass through to reach a particular network) as its sole metric • RIP has a maximum hop count of 15 • As a result RIP does not work in large network • RIP is capable of load balancing

  5. RIP: Routing Information Protocol • RIP’s administrative distance is 120 for both RIPv1 and RIPv2. • RIPv1 sends routing updates via multicast address 255.255.255.255 • RIPv2 sends routing updates via multicast address 224.0.0.9. • Cisco routers don’t enable RIPv2 by default. • RIP automatically summarizes routing updates. You can disable this by using the no auto-summary command.

  6. Distance VectorRouting Concepts

  7. RIP LAB

  8. Enabling RIP • Enabling RIP • Router(config)# router rip • Associates a network with RIP routing protocol • Router (config-router)# network ip-address • R1(config-router)#network 192.168.12.0 • Network 0.0.0.0 advertise all the network • Verifying • Router#showip route • Router#showiproute 1.1.1.0 • Router#showip protocols

  9. RIP v2 • Support plain text and MD5 authentication • Classless inter domain routing CIDR • Variable length subnet mask VLSM • Route summarization • Enabling RIP v2 • Router(config)#Router RIP • Router(config-router)#version 2

  10. Enabling RIP • Allowing unicast update for RIP: to control the set of interfaces with which you want to exchange routing information, you can disable the sending of routing updates by the command passive-interface • Router(config-router)#passive-interface loopback 0 • Define a neighbor router with which to exchange routing information • Router (config-router)#neighbor ip-address • RIP broadcast • Router(config-if)#ip ripv2-broadcast

  11. RIP timers • Router(config-router)# timers basic update invalid holddown flush • The rate at witch routing updates are sent(30 s) • The interval of time after witch a route is declared invalid(180 s) • The interval during witch we wait before we accept any new updates for the route that is in holddown (180 s) • The amount of time that must pass before a route is removed from the routing table(240 s) • Router(config-if)#ip rip advertise 30

  12. RIP timers Turnethe RIP timers so convergence is 6 time faster than the default. Your change should not effect the route between R1 and R2 • Router(config-router)#timers basic 5 30 30 40 • R1(config)#interface f 0/0 • R1(config-if)#ip rip advertise 30 • R2(config)#interfaces f0/0 • R2(config-if)#ip rip advertise 30

  13. Specifying a rip version Send and receive RIP version 1 or 2 • Router(config-if)# ip rip send version 1 • Router(config-if)# ip rip send version 1 2 • Router(config-if)# iprip receive version 2 • Router(config-if)# ip rip receive version 1 2

  14. Enabling RIP Authentication RIP support two types of authentication: plain text and MD5 • Router(config)#key chain chain-name • Router(config-keychian)#key key-identifier • Router(config-keychain-key)#key-string password • Router(config-if)# ip rip authentication Key-chain chain-name • Router(config-if)# iprip authentication mode {text|md5}

  15. Enabling RIP Authentication • Router(config)#key chain chain1 • Router(config-keychian)#key 1 • Router(config-keychain-key)#key-string cisco • Router(config-if)# ip rip authentication Key-chain chain1 • Router(config-if)# ip rip authentication mode {text|md5}

  16. RIP route summarization • Disabling automatic route summarization • Router(config-router)#no auto-summary • Router(config-if)#ip summary-address rip ip- address network-mask • Verifying • Router# show ip protocols • Router# show ip rip database • Router# show ip route

  17. Routing loop • A routing loop is a situation where a packet keeps getting routed between two or more routers because of problems in the routing table. • In case of distance vector protocols, the fact that these protocols route by rumor and have a slow convergence time can cause routing loops.

  18. Preventive measures • Problem: Counting to infinity: • Solution: defining a maximum hop count • Poison route • Reverse poison • Split horizon and split horizon with poison reverse • Hold down timer

  19. Split Horizon • The split horizon rule states that routing information learned from one interface cannot be advertised back to that interface. • By default split horizon is enabled for RIP.

  20. Route Poisoning • Route poisoning uses the maximum hop counts to stop network loops. When a router looses a route, it advertises that route with a hop count of more than the maximum hop count. The receiving router now finds the destination network unreachable and advertises it ahead as such.

  21. Hold Down • This feature prevents a router from learning new information about a failed route. When a router receives an information about an unreachable route, a holddown timer is started. The router ignores all routing updates for that route until the timer expires (by default, 180 seconds in RIP).

  22. Troubleshooting Router# show ip protocols Router# Show ip rip database Router# debug ip rip Router# show ip interface brief Router# show ip route Router# show ip route 1.1.1.0

  23. Connecting RIP to WAN There are two problems when using rip • The periodic update by rip usually prevent WAN circuits from being closed • The overhead of periodic RIP transmission could seriously interrupt normal data transfer because of the quantity of the information that passes through the line every 30 second • To overcome this limitation , triggered extension to rip cause RIP to send information on the WAN connection only when there has been an update to the routing database • Router(config)#interface serial controller-number • Router(config-if)#ip rip triggered

  24. Applying offset to routing metrics • Offset list is used to influence the decision of the router. • We create an access list to specifying the route that we want to increase its metric. • Example : • R1(config)# access-list 1 permit 1.1.1.0 0.0.0.255 • R1(config-router)#offset-list 2 in 5 fastEthernet 0/0 • Add 5 to the metric of the access list

  25. Offset list example 1 • R1 reaches 11.11.11.0 on R2 in one hop count via f0/0 on R2 • Ensure that R1 reaches R2 via f0/1 not via F0/0 on R2 • We create an access-list on router R2 • R2(config)#access-list 1 permit 11.11.11.0 0.0.0.255 • We create an offset list on R2 • R2(config-router)#offset-list 1 out 6 fastEthernet 0/0 • we added 6 hop from R1 to R2 via f0/0 soooo • R1 choses another route to reach R1 with lower metric

  26. R1 newer routing table

  27. Example #2 • R3 reaches R2 in one hop count via f0/1 on R2 • Ensure that R3 reaches R2 via f0/0 not via F0/0 on R2 • We create an access-list on router R3 • R3(config)#access-list 2 permit 11.11.11.0 0.0.0.255 • We create an offset list on R3 • R3(config-router)#offset-list 2 in 5fastEthernet0/1 • we added 5 hops from R2 to R3 via f0/1 soooo • R3 choses another route to reach R1 with lower metric

  28. Change the AD • We need that R1 does not place 2.2.2.0/24 in its routing table • R1(config)#access-list 3 permit 2.2.2.0 0.0.0.255 • R1(config)# router RIP • R1(config-router)# distance 255 0.0.0.0 255.255.255.255 3

  29. RIP messages uses UDP datagrams on port 520 Implemented in Unix systems by the ‘routed’ daemon. Size of datagram limited to 512 bytes (allow advertisement of 25 routes. Command: 8 bits Request (1), reply (2) Version: 1 or 2 Family: of protocol used for TCP/IP it is 2 Network address : 32 bytes Distance: hop count from the advertising router to the destination network Response: solicited or unsolicited. RIP message format

  30. RIP message example

  31. Reference • http://www.cisco.com/c/en/us/td/docs/routers/crs/software/crs_r4-0/routing/command/reference/b_rr40crs1book/b_rr40crs1book_chapter_0111.html • https://tools.ietf.org/html/rfc1058

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