 RIP — A distance vector interior routing protocol  IGRP — The Cisco distance vector interior routing protocol (not used nowadays)  OSPF — A link-state interior routing protocol  EIGRP — The Cisco advanced distance vector interior routing protocol  BGP — A distance vector exterior routing protocol 2ITCN

 Distance vector routing in general  /30 addressing on serial links  RIP version 2 ◦ Problems ◦ Configuration ◦ Troubleshooting  IGRP overview 3ITCN

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 To reduce routing loops and counting to infinity, RIP uses the following: ◦ Counting to infinity ◦ Split horizon ◦ Poison reverse ◦ Holddown counters ◦ Triggered updates 5ITCN

 Only ever 2 hosts on a serial link  No need to waste a whole /24 (Class C) address – use RFC 1918  Solution is to use a small subnetwork  /30 ( )  /30 has FOUR addresses, two of which are for the serial interfaces  What are the other TWO unused addresses called? 6ITCN

Routing Information Protocol It was first defined in RFC 1058 (1988) RIP Version 2 (RFC 2453) RIP has been adapted, known as RIPng (RFC 2080, 1997), for use with IPv6 7ITCN

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 Using router rip and network commands to enable RIP  Enabling RIP on an IP-addressed network  Monitoring IP packet flow using the show ip protocol command  The show ip route command 9ITCN

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 IP classless only affects the operation of the forwarding processes in Cisco IOS Software; it does not affect the way the routing table is built.  When this feature is disabled, any packets received that are destined for a subnet that numerically falls within the router’s subnetwork addressing scheme are discarded. 12ITCN

Rochester#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is not set R /24 [120/1] via , 00:00:14, Serial0/ /30 is subnetted, 1 subnets C is directly connected, Serial0/0 13ITCN

Rochester#show ip protocols Routing Protocol is "rip" Sending updates every 30 seconds, next due in 22 seconds Invalid after 180 seconds, hold down 180, flushed after 240 Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Redistributing: rip Default version control: send version 1, receive any version Interface Send Recv Triggered RIP Key-chain Serial0/ Automatic network summarization is in effect Maximum path: 4 Routing for Networks: Passive Interface(s): Routing Information Sources: Gateway Distance Last Update :00:25 Distance: (default is 120) 14ITCN

Rochester#show ip interface FastEthernet0/0 is up, line protocol is up (connected) Internet protocol processing disabled FastEthernet0/1 is administratively down, line protocol is down (disabled) Internet protocol processing disabled Serial0/0 is up, line protocol is up (connected) Internet address is /30 Broadcast address is Address determined by setup command MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is disabled Outgoing access list is not set Inbound access list is not set Proxy ARP is enabled Security level is default Split horizon is enabled ICMP redirects are always sent ICMP unreachables are always sent ICMP mask replies are never sent IP fast switching is disabled IP fast switching on the same interface is disabled etc etc……….. 15ITCN

Rochester# debug ip rip RIP protocol debugging is on Rochester#RIP: received v1 update from on Serial0/ in 1 hops RIP: sending v1 update to via Serial0/0 ( ) RIP: build update entries network metric 1 RIP: sending v1 update to via FastEthernet0/0 ( ) RIP: build update entries network metric 2 network metric 1 RIP: received v1 update from on Serial0/ in 1 hops 16ITCN

 Load balancing is a concept that allows a router to take advantage of multiple best paths to a given destination. 17ITCN

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 A router running RIP can receive a default route via an update from another router running RIP.  Another option is for the router to generate the default route itself.  The static routes can be removed using the no ip route global configuration command.  The administrator can override a static route with dynamic routing information by adjusting the administrative distance values. 19ITCN

A classful routing protocol Never used today!! No field for a subnet mask Classful protocols have become less popular as they are wasteful of IP address space 20ITCN

Triggered update is sent immediately in response to some change in the routing table 21ITCN

Originally defined in RFC Key characteristics include the following: ◦ A distance vector routing protocol. ◦ Hop count is the metric for path selection. ◦ If the hop count exceeds 15, the packet is discarded. ◦ By default, routing updates are broadcast every 30 seconds. 22ITCN

 RIP is simple to setup  Show commands for checking RIP  Debug for showing detailed running information  IGRP not really used any longer 23ITCN

 ITCN