Scenario 33 Answers

1 To address this network, what class of address would you apply to the Internet? The network could be addressed using a Class C address.

2 Could you use VLSM? Give reasons for your answer.

VLSM can be used as long as a routing protocol is used to support the propagation of the subnet mask. It would be useful to have VLSM for the WAN links, but not essential.

3 If you could use VLSM, write out the masks that you would deploy in binary notation. The bit allocation could be as follows:

Remote Subnet Locations Hosts

This would allow for six remote subnet locations, with 30 hosts on each subnet. The assumption was that the company was more likely to expand each existing location than to increase the number of remote sites. If the reverse were true, the mask would no longer be appropriate, and a single Class C may no longer be sufficient.

Because there are only three remote sites, with five networks to address and three WAN point-to-point links, and because there are six available subnets, one of the subnets could be further subnetted. This subnet would be used to address the WAN links. Another alternative is to use ip unnumbered on the serial links.

Remote Subnet Locations Hosts



00000—Taken for WAN links

New mask:


This would allow 14 WAN links to be identified.

NOTE It is possible to address more links with the use of subnet zero.

4 Could summarization be implemented?

In this size of a network, summarization is not a concern and would not be possible; also, there is no hierarchy in the physical design.

It should be noted that this design does not allow for much network growth, and the organization may want to consider using a private Class B network.

This chapter covers the following topics that you will need to master to pass the CCNP/ CCDP Routing exam:

• Explaining the routing process.

• Determining the requirements of the routing process.

• Analyzing the routing table.

• Describing the differences between a classful and classless routing protocol.

• Comparing the difference between a distance vector and link-state routing protocol, including an explanation of how routing tables are maintained, path selection, administrative distance, metrics, and convergence.

• Reviewing Cisco features that include show ip route and clear ip route.

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