Objectives. Review: Classful addresses. RIPv1 Characteristics. RIP Operation. RIP version 1

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1 2007 isco Systems, Inc. All rights reserved. isco Public Objectives IP version 1 outing Protocols and oncepts hapter 5 Describe the functions, characteristics, and operation of the IPv1 protocol. onfigure a device for using IPv1. Verify proper IPv1 operation. Describe how IPv1 performs automatic summarization. onfigure a default route and propagate it to other routers using IPv1 ITE P v4.0 hapter eview: lassful addresses IPv1 haracteristics IP addresses are divided into classes lass A /8 lass B /16 lass /24 A classful network address (or major network) is not subnetted. Uses default mask. Examples: /24, /16, /8 IPv1 is a classful routing protocol It does not send subnet masks in routing updates 3 A classful Distance Vector routing protocol - updates do not contain any information about subnet masks used with subnets, so cannot use VLSM addressing Metric = hop count outes with a hop count > 15 are unreachable ( infinity is 16) Updates are broadcast every 30 seconds Default administrative distance (AD) is IP Operation IP uses 2 message types: equest message -This is sent out on startup by each IP enabled interface -equests all IP enabled neighbors to send esponse message -Message sent to requesting router containing IP messages are encapsulated in a UDP segment with source and destination ports of

2 Basic IPv1 onfiguration (Scenario A) Basic IPv1 onfiguration A typical topology suitable for use by IPv1 includes: 5 class networks 7 8 Basic IPv1 onfiguration The network ommand Enable IP process on the router (config)# router rip 2(config)# router rip 2(config-router)# network (config-router)# network (config-router)# network Use network command to - Enable IP on all interfaces belonging to the network - Advertise this network in IP updates to other routers network <classful-network> The network number used in the network statement must be classful (i.e. a major network number) If you enter a subnet number, the IOS will automatically change it to a major network number 9 The network command does two things: It determines which local interfaces will be running IP IP updates will only be sent and received by interfaces with IP addresses in the network It determines which of the directly connected networks will be advertised 10 Verification and Troubleshooting To verify and troubleshoot routing, use the following commands: /24 is directly connected, FastEthernet0/ /24 is directly connected, Serial0/0/ /24 [120/1] via , 00:00:07, Serial0/0/ /24 [120/1] via , 00:00:07, Serial0/0/ /24 [120/2] via , 00:00:07, Serial0/0/0 show ip route show ip protocols debug ip rip /24 [120/1] via , 00:00:02, Serial0/0/ /24 is directly connected, Serial0/0/ /24 is directly connected, FastEthernet0/ /24 is directly connected, Serial0/0/ /24 [120/1] via , 00:00:09, Serial0/0/ /24 [120/2] via , 00:00:24, Serial0/0/ /24 [120/1] via , 00:00:24, Serial0/0/ /24 [120/1] via , 00:00:24, Serial0/0/ /24 is directly connected, Serial0/0/ /24 is directly connected, FastEthernet0/0 3# 12

3 show ip protocols outing Protocol is "rip" Sending updates every 30 seconds, next due in 26 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 edistributing: rip Default version control: send version 1, receive any version Interface Send ecv Triggered IP Key-chain Serial0/0/ FastEthernet0/ Automatic network summarization is in effect Maximum path: 4 outing for Networks: Passive Interface(s): outing Information Sources: Gateway Distance Last Update :00:02 Distance: (default is 120) Using IPv1 with subnets IPv1 can be used with subnetted networks providing that The major network is subnetted using only one subnet mask: all subnets are the same size cannot support VLSM The subnets of a major network number are contiguous otherwise some subnets may not be reachable IPv1 using subnets (Scenario B) 3 subnets of a class B network: /24 2 class networks: /24, / IPv1 using subnets outing tables for 1 and 2 Q: When IP receives an update for a subnet, how does it know what subnet mask is to be used with that subnet? A: It uses this rule: If the subnet update and the interface on which it is received belong to the same major network, the subnet mask of the interface is applied to the network in the routing update. Otherwise the classful subnet mask of the major network is applied to the subnet in the routing update is directly connected, FastEthernet0/ is directly connected, Serial0/0/ [120/1] via , 00:00:27, Serial0/ /24 [120/1] via , 00:00:27, Serial0/ /24 [120/2] via , 00:00:27, Serial0/ [120/1] via , 00:00:24, Serial0/ is directly connected, Serial0/0/ is directly connected, FastEthernet0/ /24 is directly connected, Serial0/0/ /24 [120/1] via , 00:00:24, Serial0/1 18

4 Passive interface command Used to prevent a router from sending updates through a specified interface passive-interface <int> All routing protocols support this command router rip network passive-interface fa0/0 emoving the routing protocol To remove the IP routing protocol from a router, enter the command: (config)# no router rip This will also remove the network statements Look at the running-configuration to check: # show run Automatic Summarization IP automatically summarizes classful networks Boundary routers summarize IP subnets from one major network to another. outing tables for 1 and [120/1] via , 00:00:24, Serial0/ is directly connected, Serial0/0/ is directly connected, FastEthernet0/ /24 is directly connected, Serial0/0/ /24 [120/1] via , 00:00:24, Serial0/1 3# /16 [120/1] via , 00:00:19, Serial0/ /24 is directly connected, Serial0/ /24 is directly connected, FastEthernet0/ Automatic Summarization Advantages of automatic summarization The size of routing updates is reduced Single routes are used instead of multiple routes which results in faster lookup in the Disadvantages Does not support discontiguous subnets 23 24

5 Lab 5.6.1: Scenario unning IPv1 on a stub network 1 and 2 are company routers running IP 3 is the ISP router connecting the ompany to the Internet Setup a static route between ompany and ISP Setup default routes on company routers to the ISP Default oute and IPv1 Packets for networks not in the should be sent through the interface defined in the default route 2(config)#ip route S0/1 This default is propagated to all the ompany s routers 2(config)#router rip passive-interface Fa0/0 network default-information originate The ISP configures a static summary route for the ompany s networks 3(config)#ip route S0/1 27 Gateway of last resort is to network is directly connected, FastEthernet0/ is directly connected, Serial0/0/ [120/1] via , 00:00:06, Serial0/0/0 * /0 [120/1] via , 00:00:05, Serial0/0/0 Gateway of last resort is to network [120/1] via , 00:00:17, Serial0/0/ is directly connected, Serial0/0/ is directly connected, FastEthernet0/ /24 is directly connected, Serial0/0/1 S* /0 is directly connected, Serial0/0/ /22 is subnetted, 1 subnets S is directly connected, Serial0/0/ /24 is directly connected, Serial0/0/ /24 is directly connected, FastEthernet0/0 3# 28 Summary Summary: ommands used by IP IPv1 characteristics include: lassful, distance vector routing protocol Hop count is the metric Broadcasts updates every 30 seconds Does not support VLSM Does not support discontiguous subnets Automatically summarizes subnets across classful network boundaries 29 # debug ip rip ommand (config)# router rip network <network-no> passive-interface fa0/0 default-information originate # show ip protocols ommand s purpose Enables IP routing process Associates a network with a IP routing process Prevent IP updates from going out an interface Used by IP to propagate default routes Used to display timers used by IP Used to view real time IP routing updates 30