Routing Protocols and Concepts: Chapter 7 potx

Chapter 7 RIP version 2 Routing Protocols and Concepts 2 Topics  RIPv1 Limitations  RIPv1: Topology Limitations  RIPv1: Discontiguous Networks  RIPv1: No VLSM Support  RIPv1: No CIDR Support  Configuring RIPv2  Enabling and Verifying RIPv2  Auto-Summary and RIPv2  Disabling Auto-Summary in RIPv2  Verifying RIPv2 Updates  VLSM and CIDR  RIPv2 and VLSM  RIPv2 and CIDR  Verifying and Troubleshooting RIPv2  Verification and Troubleshooting Commands  Common RIPv2 Issues  Authentication RIPv1 Limitations  RIPv1: Topology Limitations  RIPv1: Discontiguous Networks  RIPv1: No VLSM Support  RIPv1: No CIDR Support 4 Note on Classful Routing Protocols, RIPv1 limitations  The first part of this presentation discusses the limitations of classful routing protocols such as RIPv1.  RIPv1 is used as an example, so we can see how RIPv2 a classless routing protocol does not have these same limitations.  Classful routing protocols have three major limitations:  Does not support discontiguous networks.  Does not support VLSM  Does not support CIDR  Instead of just “memorizing” these facts, we will demonstrate and “understand” why a classful routing protocol has these limitations. 5 RIPv1: Distance Vector, Classess Routing Protocol  RIP Version 2 (RIPv2) is defined in RFC 1723.  RIPv2 is the first classless routing protocol discussed in this book.  RIPv2 has lost popularity when compared to other routing protocols such as EIGRP, OSPF and IS-IS.  RIPv2, it is ideal for explaining the differences between a classful routing protocol (RIPv1) and a classless routing protocol (RIPv2). 6 RIPv1 and RIPv2  RIPv2 is actually an enhancement of RIPv1’s features and extensions rather than an entirely new protocol.  Next-hop addresses included in the routing updates  Use of multicast addresses in sending updates  Authentication option available  Both versions of RIP share the following features and limitations:  Use of hold-down and other timers to help prevent routing loops  Use of split horizon and split horizon with poison reverse to also help prevent routing loops  Use of triggered updates when there is a change in the topology for faster convergence  Maximum hop count of 15 hops, with the hop count of 16 signifying an unreachable network 7  In a discontiguous network, a classful major network address, such as 172.30.0.0/16, is separated by one or more other major networks.  172.30.0.0/16 is divided by the networks:  209.165.200.228/30  209.165.200.232/30  Classful routing protocols do not include enough routing information to route properly for discontiguous networks. RIPv1 Limitations 172.30.0.0 /16 172.30.0.0 /16 8  R2: static summary route to the 192.168.0.0/16 network.  Redistribution - Inject static route(s) into routing protocol updates.  For now, this summary route will cause problems with RIPv1 because:  192.168.0.0/16 is not a major classful address (192.168.0.0/24)  Includes all the /24 versions of 192.168.0.0/16 Summary Route 172.30.0.0/16 172.30.0.0 /16 R2(config)# ip route 192.168.0.0 255.255.0.0 null0 9  R1 and R3 contain VLSM networks.  Both R1 and R3 are configured with /24 subnets of the 172.30.0.0/16 network.  R3: 172.30.200.0/24 subnetted again, using the first 4 bits for subnets and the last 4 for hosts.  172.30.200.16/28 and 172.30.200.32/28 VLSM 172.30.0.0/16 172.30.0.0 /16 10 VLSM  R3: 172.30.200.0/24 subnetted again, using the first 4 bits for subnets and the last 4 for hosts.  172.30.200.16/28 and 172.30.200.32/28 [...]... 172 . 17. 1.0/24 172 . 17. 2.0/24 1 1 10.1.1.0/24 2 1 Apply /24 interface mask 172 . 17. 1.0 Apply /8 classful mask 10.0.0.0 (summary) 32 Example 5 172 . 17. 1.0/24 1 172 . 17. 2.0/24 1 172 . 17. 3.0/24 2 1 33 Example 5 172 . 17. 1.0/24 172 . 17. 2.0/24 1 1 172 . 17. 3.0/24 2 1 Apply /24 interface mask 172 . 17. 1.0 Apply /24 interface mask 172 . 17. 3.0 34 Example 6 172 . 17. 1.0/24 1 172 .16.2.0/24 1 172 . 17. 3.0/24 2 1 35 Example 6 172 . 17. 1.0/24... 192.168.1.0/24 2 1 27 Example 2 172 . 17. 0.0/16 172 .16.0.0/16 1 1 192.168.1.0/24 2 1 Apply /16 classful mask 172 . 17. 0.0 Apply /24 classful mask 192.168.1.0 28 Example 3 172 . 17. 1.0/24 1 172 .16.0.0/16 1 10.1.1.0/24 2 1 29 Example 3 172 . 17. 1.0/24 1 172 .16.0.0/24 1 10.1.1.0/24 2 1 Apply /16 classful mask 172 . 17. 0.0 (summary) Apply /8 classful mask 10.0.0.0 (summary) 30 Example 4 172 . 17. 1.0/24 1 172 . 17. 2.0/24 1 10.1.1.0/24... Serial0/0/0 R1 has its own 172 .30.0.0 routes: 172 .30.2.0/24 172 .30.1.0/24 R1 does not send R2 those subnets R1 and R3 are boundary routers only sending the summarized 172 .30.0.0 Result, R2 only knows about the 172 .30.0.0/16 classful network and is unaware of any 172 .30.0.0 subnets 23 Determining the mask and network address Receiving an Update: Determining subnet mask for routing table What is the major... included in the update, RIPv1 and other classful routing protocols must summarize networks at major network boundaries 19 RIPv1: Discontiguous Networks RIPv1 on both Routers R1 and R3 will summarize their 172 .30.0.0 subnets to the classful major network address of 172 .30.0.0 when sending routing updates to R2 20 Examining the Routing Tables R2# show ip route R C C C S 172 .30.0.0/16 [120/1] via 209.165.200.230,... from one routing source and sending those routes to another routing source Routes can only be redistributed into a dynamic routing protocol Dynamic routing protocol to a different dynamic routing protocol Static routes to a dynamic routing protocol Directly connected networks to a dynamic routing protocol Want R2 to redistribute our static route (192.168.0.0/16) by importing the route into RIPv1 and then... 172 . 17. 1.0 Apply /24 interface mask 172 . 17. 3.0 34 Example 6 172 . 17. 1.0/24 1 172 .16.2.0/24 1 172 . 17. 3.0/24 2 1 35 Example 6 172 . 17. 1.0/24 1 172 .16.2.0/24 1 172 . 17. 0.0 (Summary) Apply /16 classful mask (route not used) 172 . 17. 3.0/24 2 1 Apply /16 classful mask (route not used) 172 . 17. 0.0 (Summary) 36 ... R2 has two equal-cost routes to the 172 .30.0.0/16 network R1 and R3 are sending R2 a RIPv1 update for the 172 .30.0.0 network with a metric of 1 hop R2’s routing table only contains the major classful network address of 172 .30.0.0 and adds the Class B subnet mask of /16 21 debug ip rip R2# debug ip rip RIP: received v1 update from 209.165.200.230 on Serial0/0/0 172 .30.0.0 in 1 hops RIP: received v1... to R1 and R3 using the RIPv1 process We will see whether this is indeed happening, and if not, why not 15 Verifying and Testing Connectivity R2# ping 172 .30.1.1 Type escape sequence to abort Sending 5, 100-byte ICMP Echos to !U!.! Success rate is 60 percent (3/5), R2# ping 172 .30.100.1 Type escape sequence to abort Sending 5, 100-byte ICMP Echos to !U!.! Success rate is 60 percent (3/5), R2# 172 .30.1.1,...Private Addresses and Cisco Example Addresses RFC 1918 Private Addresses Cisco Example Addresses We use RFC 1918 and Cisco Example addresses for all topologies 11 Loopback Interfaces 172 .30.0.0/16 172 .30.0.0 /16 Loopback interface Software-only interface Used to emulate an interface Can be assigned an IP address Specific purposes with some routing protocols such as OSPF (later) A loopback... network in the routing update? Are they the same major classful network address? Yes: Send subnet network address No: Send summary address – the classful network address 24 Example 1 10.0.0.0/8 1 172 .16.0.0/16 1 192.168.1.0/24 2 1 25 Example 1 10.0.0.0/8 172 .16.0.0/16 1 1 192.168.1.0/24 2 1 Apply /8 classful mask 10.0.0.0 Apply /24 classful mask 192.168.1.0 26 Example 2 172 . 17. 0.0/16 1 172 .16.0.0/16 . 172 .30.0.0/16 network.  R3: 172 .30.200.0/24 subnetted again, using the first 4 bits for subnets and the last 4 for hosts.  172 .30.200.16/28 and 172 .30.200.32/28 VLSM 172 .30.0.0/16 172 .30.0.0 /16 10 VLSM . Enabling and Verifying RIPv2  Auto-Summary and RIPv2  Disabling Auto-Summary in RIPv2  Verifying RIPv2 Updates  VLSM and CIDR  RIPv2 and VLSM  RIPv2 and