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Semester 3 

Module 1: Introduction to Classless Routing - Overview

Network administrators must anticipate and manage the physical growth of networks. This may require them to buy or lease another floor of a building for new network equipment such as racks, patch panels, switches, and routers. Network designers must choose address schemes that allow for growth. Variable-length subnet mask (VLSM) is used to create efficient and scalable address schemes.

Almost every enterprise must implement an IP address scheme. Many organizations select TCP/IP as the only routed protocol to run on their networks. Unfortunately, the architects of TCP/IP did not predict that the protocol would eventually sustain a global network of information, commerce, and entertainment.

IPv4 offered an address strategy that was scalable for a time before it resulted in an inefficient allocation of addresses. IPv4 may soon be replaced with IP version 6 (IPv6) as the dominant protocol of the Internet. IPv6 has virtually unlimited address space and implementation has begun in some networks. Over the past two decades, engineers have successfully modified IPv4 so that it can survive the exponential growth of the Internet. VLSM is one of the modifications that has helped to bridge the gap between IPv4 and IPv6.

Networks must be scalable since the needs of users evolve. When a network is scalable it is able to grow in a logical, efficient, and cost-effective way. The routing protocol used in a network helps determine the scalability of the network. It is important to choose the routing protocol wisely. Routing Information Protocol version 1 (RIP v1) is suitable for small networks. However, it is not scalable to large networks. RIP version 2 (RIP v2) was developed to overcome these limitations.

This module covers some of the objectives for the CCNA 640-801 and ICND 640-811 exams.  

Students who complete this module should be able to perform the following tasks:

  • Define VLSM and briefly describe the reasons for its use
  • Divide a major network into subnets of different sizes using VLSM
  • Define route aggregation and summarization as they relate to VLSM
  • Configure a router using VLSM
  • Identify the key features of RIP v1 and RIP v2
  • Identify the important differences between RIP v1 and RIP v2
  • Configure RIP v2
  • Verify and troubleshoot RIP v2 operation

Configure default routes using the ip route and ip default-network commands 


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