CCE1030 Computer Networking Lecture 19 Routing Information Protocol RIPv1 Usama Arusi January 2018 CCE1030 Usama Arusi

Outcomes Describe the characteristics, and operation of the RIPv1 protocol Demonstrate device configuration using RIPv1 Verify proper RIPv1 operation Describe how RIPv1 performs automatic summarization Illustrate how to troubleshoot default routes propagated in a routed network implementing RIPv1 January 2018 CCE1030 Usama Arusi

Recap: Routing Protocols Routers are the main devices used to connect networks. They forward packets in a network from source to destination. Use forwarding tables. Entries in forwarding tables can be set manually or automatically. Routing protocols are used to automatically set forwarding tables. January 2018 CCE1030 Usama Arusi

Recap: Routing Protocols Routing protocols use a hierarchical structure Static – manually configured Dynamic – routing protocols Dynamic routing consists of routing tables that are built and maintained automatically through an on going communication between routers Routing protocols grouped according to characteristics January 2018 CCE1030 Usama Arusi

Recap: Routing Protocols Types of routing protocols: Interior Gateway Protocols (IGP) Used for routing inside an autonomous system & used to route within the individual networks themselves Examples: RIP, EIGRP, OSPF Exterior Routing Protocols (EGP) Used for routing between autonomous systems Example: BGPv4 January 2018 CCE1030 Usama Arusi

Recap: Distance Vector routing One of the two major classes of intra domain routing protocols Routes are advertised as vectors of (distance, direction), where distance is defined in terms of a metric and direction is defined in terms of the next-hop router For example: Destination A is a distance of 5 hops away, in the direction of next-hop router X January 2018 CCE1030 Usama Arusi

Content Characteristics, and operation of the RIPv1 protocol. Configure a device for using RIPv1. Verify proper RIPv1 operation. Automatic summarization. Configure, verify, and troubleshoot default routes. January 2018 CCE1030 Usama Arusi

RIP Characteristics A classful, Distance Vector (DV) routing protocol Cost metric = hop count Each link has a cost of 1 Routes with a hop count > 15 are unreachable Limiting network size Updates are broadcast every 30 seconds Using a RIP response message – containing a list of up to 25 destinations January 2018 CCE1030 Usama Arusi

RIP Operation RIP uses 2 message types: Request message This is sent out on startup by each RIP enabled interface Requests all RIP enabled neighbours to send routing table Response message Message sent to neighbouring router containing routing table This message might be a response to a request, or it might be an update message generated by the sender January 2018 CCE1030 Usama Arusi

Forwarding Information Base RIPv1 protocol keeps the following information about each destination: IP address—IP address of the destination host or network Gateway—The first gateway along the path to the destination Interface—The physical network that must be used to reach the destination Metric—A number indicating the number of hops to the destination Timer—The amount of time since the entry was last updated January 2018 CCE1030 Usama Arusi

Subnet Masks in Routing Updates IP addresses initially divided into classes Class A Class B Class C RIP is a classful routing protocol Does not send subnet masks in routing updates January 2018 CCE1030 Usama Arusi

Administrative Distance Multiple routing protocols may exist on any one given network Most routing protocols have metric structures and algorithms that are not compatible with other protocols The exchange of route information and the selection of the best path across the multiple protocols are critical Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols January 2018 CCE1030 Usama Arusi

Administrative Distance Administrative distance defines the reliability of a routing protocol It is the first criterion that a router uses to determine which routing protocol to use if two protocols provide route information for the same destination It has only local significance It is not advertised in routing updates January 2018 CCE1030 Usama Arusi

Administrative Distance RIP’s default administrative distance is 120 January 2018 CCE1030 Usama Arusi

Basic RIPv1 Configuration A typical topology suitable for use by RIPv1 includes: Three router set up No PCs attached to LANs Use of 5 different IP subnets January 2018 CCE1030 Usama Arusi

Basic RIPv1 Configuration To activate RIP on the router the protocol stack has to be turned on To enable RIP enter: Router rip at the global configuration prompt Prompt will look like R1(config-router)# January 2018 CCE1030 Usama Arusi

Basic RIPv1 Configuration Specifying Networks R1 has 2 directly connected networks Enable RIP on all interfaces that belong to this network Advertise this network in RIP updates sent to other routers every 30 seconds Repeat process for R2 and R3 January 2018 CCE1030 Usama Arusi

Verification and Troubleshooting To verify and troubleshoot routing use the following commands: show ip route show ip protocols debug ip rip January 2018 CCE1030 Usama Arusi

Verification and Troubleshooting Verify and troubleshoot commands: show ip route show ip protocols Displays routing protocol configured on router debug ip rip January 2018 CCE1030 Usama Arusi

Verification and Troubleshooting Verify and troubleshoot commands: show ip route show ip protocols debug ip rip Used to display RIP routing updates as they are happening January 2018 CCE1030 Usama Arusi

Verification and Troubleshooting Passive interface command Used to prevent a router from sending updates through an interface January 2018 CCE1030 Usama Arusi

Automatic Summarization RIP uses automatic summarization to reduce the size of a routing table Example: Three classful networks are used: 172.30.0.0/16 192.168.4.0/24 192.168.5.0/24 The 172.30.0.0/16 network is subnetted into three subnets: 172.30.1.0/24 172.30.2.0/24 172.30.3.0/24 January 2018 CCE1030 Usama Arusi

Automatic Summarization Boundary Router Is a router that has interfaces in more than one major classful network Boundary routers summarize RIP subnets from one major network to another January 2018 CCE1030 Usama Arusi

Automatic Summarization Processing RIP Updates January 2018 CCE1030 Usama Arusi

Automatic Summarization Advantages of automatic summarization: The size of routing updates is reduced Single routes are used to represent multiple routes which results in faster lookup in the routing table Disadvantage of Automatic Summarization: Does not support discontiguous networks January 2018 CCE1030 Usama Arusi