1 © 2003, Cisco Systems, Inc. All rights reserved. CCNA 3 v3.0 Module 1 Introduction to Classless Routing

222 © 2003, Cisco Systems, Inc. All rights reserved. Objectives VLSM RIP version 2

333 © 2003, Cisco Systems, Inc. All rights reserved. What Is VLSM and Why Is It Used?

444 © 2003, Cisco Systems, Inc. All rights reserved. A Waste of Space

555 © 2003, Cisco Systems, Inc. All rights reserved. When to Use VLSM?

666 © 2003, Cisco Systems, Inc. All rights reserved. VLSM - Calculating Subnets with VLSM

777 © 2003, Cisco Systems, Inc. All rights reserved. Use this procedure to further subnet /20 to /26: Step 1 Write in binary form. Step 2 Draw a vertical line between the 20th and 21st bits, as shown in Figure. /20 was the original subnet boundary. Step 3 Draw a vertical line between the 26th and 27th bits, as shown in Figure. The original /20 subnet boundary is extended six bits to the right, becoming /26. Step 4 Calculate the 64 subnet addresses using the bits between the two vertical lines, from lowest to highest in value. The figure shows the first five subnets available.

888 © 2003, Cisco Systems, Inc. All rights reserved. VLSM Labs

999 © 2003, Cisco Systems, Inc. All rights reserved. A) 60 hosts required using = 62 therefore bits required xxxxxx =.0/ 26 B) 28 host required therefore 5 bits required ( = 30) xxxxx =.64/ 27

10 © 2003, Cisco Systems, Inc. All rights reserved. C) 12 hosts required therefore 4 bits required ( = 14) xxxx =.96 / 28 D) 12 hosts required therefore 4 bits required ( = 14) xxxx =.112 / 28

11 © 2003, Cisco Systems, Inc. All rights reserved. E) Only 2 hosts required therefore 2 bits required xx =.128 / 30 F) Only 2 hosts required therefore 2 bits required xx =.132 / 30 G) Only 2 hosts required therefore 2 bits required xx =.136 / 30

12 © 2003, Cisco Systems, Inc. All rights reserved. Configuring VLSM

13 © 2003, Cisco Systems, Inc. All rights reserved. A Working VLSM Example

14 © 2003, Cisco Systems, Inc. All rights reserved. Route Aggregation

15 © 2003, Cisco Systems, Inc. All rights reserved. Route Summarization

16 © 2003, Cisco Systems, Inc. All rights reserved. RIP History RIPv1 has the following limitations: It does not send subnet mask information in its updates. It sends updates as broadcasts on It does not support authentication. It is not able to support VLSM or classless interdomain routing (CIDR).

17 © 2003, Cisco Systems, Inc. All rights reserved. RIPv2 Features

18 © 2003, Cisco Systems, Inc. All rights reserved. Comparing RIPv1 and RIPv2

19 © 2003, Cisco Systems, Inc. All rights reserved. Configuring RIPv2

20 © 2003, Cisco Systems, Inc. All rights reserved. Verifying the RIP Configuration

21 © 2003, Cisco Systems, Inc. All rights reserved. Displaying the IP Routing Table

22 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting RIPv2 The debug ip rip Command

23 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting RIPv2 The debug ip rip Outputs and Meanings

24 © 2003, Cisco Systems, Inc. All rights reserved. Configuring Default Route