1. Prof. Alfred J Bird, Ph.D., NBCT http://www.cs.umb.edu/~abird abird@cs.umb.edu Office – McCormick 3rd floor 607 Office Hours – Monday 3:00 to 4:00 and Thursday 4:00PM to 5:30

2.  A router decides where to sent the packet next  Works at layer 2 (Data Link)  Routing Tables  Routing Rules (How does it decide?)  Routers are often set up in a mesh topology  Gateway Address  Network Segments

3.  What is a Routing Protocol  Routing Protocols provide a standardized format for route management including route selection, sharing route status with neighboring routers and calculating alternative routes if the best path route is down.

4.  There are basically two types of routing protocols  Static protocols  Dynamic Protocols

5.  Static Route  A static route is list of IP addresses to which data traffic can be forwarded and has been entered manually into either a router’s or a computer’s routing table.

10.  Variable Length Subnet Masking  Routes can be configured using different length subnet masks  Look at the previous example  The 10.10.200.0 subnet only needs four (4) IP addresses, so why would we want to use more.  What are the four (4) needed IP addresses?

11.  What is the path from A1 on LAN A to B1 on LAN B?  A1 LAN A – 10.10.20.1  FA0/0 on ROUTER A – 10.10.20.250  FA0/1 on Router A – 10.10.200.1  FA0/2 on Router B – 10.10.200.2  FA0/0 on Router B – 10.10.10.250  B1 on LAN B – 10.10.10.1  So we must program this information manually!

12.  What is the Gateway of Last Resort?  The IP Address of the router in your network where data packets with unknown routes should be forwarded.  The purpose is to configure a route for data packets the do not have a destination route configured in the routing table.  ip route 0.0.0.0 0.0.0.0

13.  There are two basic classes of Dynamic Routing Protocols:  Distance Vector Protocol  Link State Protocols  There are also hybrid protocols  These are a combination of the two basic protocols

14.  The primary features of a dynamic routing protocol are:  What information is exchanged between routers.  When updated routing information is exchanged.  Steps for reacting to changes in the network.  Criteria for establishing the best route selection.

15.  Path Determination  Procedure to determine best route  Metric  A numeric measure assigned to routes  Convergence  Time it takes for the router to obtain a clear view of the routes  Load Balancing  Allowing the router to use multiple data paths

16.  Hop Count  Reliability  Bandwidth  Delay  Cost  Load  Ticks

17.  A distance Vector Protocol periodically sends it routing table to its neighbors or adjacent routers.  When the neighboring router receives a table, it assigns a distance vector to each route.  The distance vector is typically specified by some metric such as hop count.

18.  RIP  Created in 1988  Uses hop count  Maximum number of hops is 15  Exchanges tables every 30 seconds  Can consume a lot of bandwidth  Slow convergence

19.  A Link State Protocol establishes a relationship with neighboring routers and uses route advertisements to build a routing table.  Key Issues:  Finds neighbors/adjacencies  Uses route advertisements to build routing tables  Sends “Hello” packets  Send updates when routing changes.  Also called Shortest Path First Protocols  Based upon the work of E. W. Dijkstra

20.  OSPF (Open Shortest Path First)  Developed by the IGP (Interior Gateway Protocol) working group of the IETF (Internet Engineering Task Force)  It is an open (non-proprietary) protocol  Supported by many vendors  Has rapid convergence  It consumes very little bandwidth  Difficult to configure  Uses VLSM

21.  IS-IS (Intermediate System to Intermediate System)  Very similar to OSPF  Designed as part of the OSI network layer service

22.  EIGRP (Enhanced Interior Gateway Routing Protocol)  A Cisco proprietary protocol.  Combines both distance vector and link state algorithm.  An enhanced version of the IGRP protocol

23.  Load the CD Software.  Go to page 368, section 9-2 in the textbook  Follow along with the activity.  Go to page 387, section 9-7 in the textbook.  Follow along with the activity.  Record all the results from your actions.  Submit a report when you have completed the activity.