Instructor & Todd Lammle

1. Instructor & Todd Lammle Sybex CCNA 640-802 Chapter 6: IP Routing

2. Chapter 6 Objectives • Understanding IP routing • Static routing • Dynamic routing • RIP • RIPv2 • Verifying routing 2

3. To route a router need to know: Remote Networks Neighbor Routers All Possible routes to remote network The absolute best route to all remote networks Maintain and verify the routing information What is Routing? A D C B

4. Basic Path Selection What interface will the router send out a packet if it has destination address of 10.10.10.18?

5. Simple IP Routing >ping 172.16.1.2 172.16.2.0 172.16.1.0 172.16.3.1 172.16.3.2 e0 e0 s0 A B B s0 172.16.2.2 Host A 172.16.1.1 172.16.2.1 172.16.1.2 Host B

6. Routing/PDU Example:Host A Web browses to the HTTP Server…. 1. The destination address of a frame will be the _______________________ 2. The destination IP address of a packet will be the IP address of the________________________________ 3. The destination port number in a segment header will have a value of __

7. Static Routes Stub Network 172.16.1.0 172.16.2.0 SO SO A A B B 172.16.3.1 172.16.3.2 Routes must be unidirectional

8. Static Route Configuration ip route remotenetwork [mask] {address|interface} [distance] [permanent] Router(config)#ip route remote_network mask next_hop

9. Static Route Example Stub Network 172.16.2.0 172.16.1.0 SO SO A B B 172.16.3.1 172.16.3.2 ip route 172.16.1.0 255.255.255.0 172.16.3.2or ip route 172.16.1.0 255.255.255.0 s0

10. Default Routes Stub Network 172.16.1.0 172.16.2.0 SO SO A B B 172.16.3.1 172.16.3.2 To send packets with a remote destination network not in the routing table to the next-hop router, only used for stub networks. ip route 0.0.0.0 0.0.0.0 172.16.3.1 ip classless

11. Routing Protocols • Routing protocols are used between routers to: • Determine the path of a packet through a network • Maintain routing tables • Two types: interior/exterior gateway protocols (I/EGPs) • Examples: • IGP: RIP, IGRP; • EGP: Border Gateway Protocol (BGP)

12. Routing Protocols EGPs: BGP IGPs: RIP, IGRP Autonomous System 1 Autonomous System 2 • An autonomous system is a collection of networks under a common administrative domain, i.e., all routers sharing the same routing table are in the same AS. • IGPs operate within an autonomous system. • EGPs connect different autonomous systems.

13. Classful Routing Overview Classful routing protocols do not include the subnet mask with the route advertisement. • Within the same network, consistency of the subnet masks is assumed. • Summary routes are exchanged between foreign networks. • Examples of classful routing protocols: • RIP Version 1 (RIPv1) • IGRP

14. Classless Routing Overview Classless routing protocols include the subnet mask with the route advertisement. • Classless routing protocols support variable-length subnet masking (VLSM). • Summary routes can be manually controlled within the network. • Examples of classless routing protocols: • RIP Version 2 (RIPv2) • EIGRP • OSPF • IS-IS

15. Administrative Distance Router B Router A IGRPAdministrative Distance=100 RIPAdministrative Distance=120 Router C Router D Default Administrative Distance Directly Connected: 0 Static Route: 1 RIP: 120 IGRP: 100 EIGRP: 90 OSPF: 110

16. Distance Vector Distance—How farVector—In which direction A D C B Routing Table Routing Table Routing Table Routing Table All routers just broadcast their entire routing table out all active interfaces on periodic time intervals Distance vector algorithms do not allow a router to know the exact topology of an internetwork.

17. Discovering Routes

18. Discovering Routes: Converged Routing Tables

19. Routing Loops

20. Stop Router Loops • Maximum hop count: RIP permits a hop count of up to 15. • Split horizon: routing information cannot be sent back in the direction from which it was received. • Route poisoning: advertising the downed network as unreachable

21. RIP Overview 64kbps T1 T1 T1 • Hop count metric selects the path, 16 is unreachable • Full route table broadcast every 30 seconds • Load balance maximum of 6 equal cost paths (default = 4) • RIPv2 supports VLSM and Discontiguous networks

22. router RIP router RIP network 172.16.0.0 network 192.168.10.0 network 172.16.0.0 network 10.0.0.0 RIP Routing Configuration Router(config)#router rip Router(config-router)#network network-number* 192.168.10.0 10.3.5.0 172.16.10.0 *Network is a classful network address. Every device on network uses the same subnet mask

23. RIP Version 2 • Allows the use of variable length subnet masks (VLSM) by sending subnet mask information with each route update • Distance Vector – same AD, and timers. • Easy configuration, just add the command “version 2” under the router rip configuration router rip network 10.0.0.0 version 2

24. RIPv1 vs. RIPv2

25. Interior Gateway Routing Protocol Maximum hop count: 255 for larger network, default 100 Composite metric: bandwidth and delay of the line. Config t router igrp 10

26. IGRP vs. RIP

27. Discontiguous Addressing • Two networks of the same classful networks are separated by a different network address 192.168.10.0/24 192.168.10.0/24 10.1.1.0/24 • RIPv1 and IGRP do not advertise subnet masks, and therefore cannot support discontiguous subnets. • OSPF, EIGRP, and RIPv2 can advertise subnet masks, and therefore can support discontiguous subnets.

28. Passive Interface Maybe you don’t want to send RIP updates out your router interface connected to the Internet. Use the passive-interface command: Router(config)#router rip Router(config-router)#passive-interface serial0 X Updates Internet S0 Gateway This allows a router to receive route updates on an interface, but not send updates via that interface

29. Verifying RIP Router#show ip protocols Router#show ip route Router#debug ip rip Router#undebug all (un all)

30. Summary • Open your books and go through all the written labs and the review questions. • Review the answers in class. 30