1. © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public ITE PC v4.0 Chapter 1 1 Introduction to Dynamic Routing Protocol Routing Protocols and Concepts – Chapter 3 Sandra Coleman, CCNA, CCAI

2. ITE PC v4.0 Chapter 1 2 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Objectives  Describe the role of dynamic routing protocols and place these protocols in the context of modern network design.  Identify several ways to classify routing protocols.  Describe how metrics are used by routing protocols and identify the metric types used by dynamic routing protocols.  Determine the administrative distance of a route and describe its importance in the routing process.  Identify the different elements of the routing table.

3. ITE PC v4.0 Chapter 1 3 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Overview of dynamic routing protocols

4. ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Dynamic Routing Protocols  Function(s) of Dynamic Routing Protocols: -Dynamically share information between routers. -Automatically update routing table when topology changes. -Determine best path to a destination.

5. ITE PC v4.0 Chapter 1 5 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Dynamic Routing Protocols  The purpose of a dynamic routing protocol is to: -Discover remote networks -Maintaining up-to-date routing information -Choosing the best path to destination networks -Ability to find a new best path if the current path is no longer available -They can NOW SHARE information with each other!

6. ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Dynamic Routing Protocols  Components of a routing protocol Algorithm In the case of a routing protocol, algorithms are used for facilitating routing information and best path determination Routing protocol messages These are messages for discovering neighbors and exchange of routing information

7. ITE PC v4.0 Chapter 1 7 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Dynamic Routing Protocols  Advantages of static routing -It can backup multiple interfaces/networks on a router -Easy to configure -No extra resources are needed -More secure -Administrator maintains control over the routing process  Disadvantages of static routing -Network changes require manual reconfiguration -Does not scale well in large topologies

8. ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Classifying Routing Protocols  Dynamic routing protocols are grouped according to characteristics. Examples include: -RIP -IGRP -EIGRP -OSPF -IS-IS -BGP  Autonomous System is a group of routers under the control of a single authority.

9. ITE PC v4.0 Chapter 1 9 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Classifying Routing Protocols  Types of routing protocols: -Interior Gateway Protocols (IGP) – routing within an AS -Exterior Gateway Protocols (EGP) – routing between AS’s

10. ITE PC v4.0 Chapter 1 10 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Classifying Routing Protocols  Interior Gateway Routing 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

11. ITE PC v4.0 Chapter 1 11 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public IGP Protocols Distance vector (RIP, EIGRP) – routes are advertised as vectors of distance & direction. – incomplete view of network topology. (only sees its neighbors) – Generally, periodic updates. (30-, 90-seconds, etc.) are sent ONLY to neighboring routers – Work best in a simple, flat network or a hub-and-spoke topology –Admins do NOT have to be very knowledgable Link state (OSPF) – complete view of network topology is created. (Sees EVERYONE – like a map) – Knowledgeable administrators – updates are not periodic. (triggered by a change) – Quicker convergence – Should be used in larger organizations with more than 5 routers (especially if some of them are NOT Cisco routers)

12. ITE PC v4.0 Chapter 1 12 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Classifying Routing Protocols  Classful routing protocols Do NOT send subnet mask in routing updates DO NOT support VLSM RIPv1 and IGRP  Classless routing protocols DO send subnet mask in routing updates. Supports VLSM RIPv2, EIGRP, OSPF, IS-IS, BGP

13. ITE PC v4.0 Chapter 1 13 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Classifying Routing Protocols  Convergence is defined as when all routers’ routing tables are at a state of consistency (They all have the SAME level of knowledge)

14. ITE PC v4.0 Chapter 1 14 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Convergence  Fast convergence is VERY desirable, especially when using dynamic routing protocols.  WHY? Routers could make incorrect forwarding decisions if the topology is NOT converged.

15. ITE PC v4.0 Chapter 1 15 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Routing Protocols Metrics  Metric A value used by a routing protocol to determine which routes are better than others. See the RIP example below!

16. ITE PC v4.0 Chapter 1 16 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Routing Protocols Metrics  Metrics used in IP routing protocols -Bandwidth – Highest preferred (EIGRP) -Cost – value determined by IOS or by network admin. -Delay – time to traverse a path -Hop count - # routers packet must pass through (RIP) -Load – traffic utilization on a certain link -Reliability – probability of a link failure (based on an algorithm)  You don’t need to understand all of these right now, we’ll discuss them as we get to the protocol they apply to.

17. ITE PC v4.0 Chapter 1 17 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Metric Example

18. ITE PC v4.0 Chapter 1 18 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Routing Protocols Metrics  The Metric Field in the Routing Table  Metric used for each routing protocol -RIP - hop count (lowest wins) -IGRP & EIGRP - Bandwidth (used by default), Delay (used by default), Load, Reliability (lowest wins) -IS-IS & OSPF – Cost, Bandwidth (Cisco’s implementation) (lowest wins)

19. ITE PC v4.0 Chapter 1 19 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public What if multiple paths have same metric?  Both are placed in the routing table and packets are balanced between the 2. To see if it is in effect, just look at the routing table.  Load balancing This is the ability of a router to distribute packets among multiple same cost paths

20. ITE PC v4.0 Chapter 1 20 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Administrative Distance of a Route  Purpose of Administrative Distance It’s a numeric value that specifies the trustworthiness of a route. Uses AD to select the best path when it learns about the same destination network from 2 or more different routing sources. Route with lowest AD is the one chosen for the routing table (Best path)

21. ITE PC v4.0 Chapter 1 21 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Administrative Distance of a Route  Identifying the Administrative Distance (AD) in a routing table It is the first number in the brackets in the routing table

22. ITE PC v4.0 Chapter 1 22 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Administrative Distance of a Route  Dynamic Routing Protocols – the lower the number, the more trustworthy the route!

23. ITE PC v4.0 Chapter 1 23 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Administrative Distance of a Route  Directly connected routes Have a default AD of 0  Static Routes Administrative distance of a static route has a default value of 1  To see the AD of a static route, use the command below:

24. ITE PC v4.0 Chapter 1 24 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Administrative Distance of a Route  Directly connected routes -Immediately appear in the routing table as soon as the interface is configured and the lines are brought up – that is the IP address is assigned to an interface! These routes have an AD of 0.

25. ITE PC v4.0 Chapter 1 25 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Ch. 3…Dynamic Routing Protocols is finished 1.Study Guide – 1.Pg. 139 – Matching 2.Pg. 142 –Dynamic Routing Protocols Classification Chart 3.Pg. 144-145 – Metric Parameters Exercise 4.Pg. 146 – Routing Sources & AD Exercise 5.Pg. 146-147 – Identifying Elements of a routing table 2.Labs - Packet Tracer Skills Integration Challenge TODAY! 3.Test on Ch. 3 will be Monday, Feb. 11, 2013 – NO HANDS ON! Just lecture notes.. MC, Tables to fill in, Interpreting the routing table. 4.If you don’t get through with the labs today, you can finish them over the weekend. 5.Online test for Ch. 3 – will be on until Sunday night, Feb. 10, 2013, midnight!