Answers to Chapter 2 Review Questions

Answers to Chapter 2 Review Questions

Refer to the network setup in Figure 2-15 to answer Questions 1 and 2.

1:

Examine Figure 2-15. How many broadcast and collision domains are there?

A:

There are 14 collision domains. Each port on a bridge, router, and switch define a new broadcast domain. You cannot easily tell how many broadcast domains exist in the network due to the presence of the switch. A switch can create one or many broadcast domains, depending upon how you configure it. If the switch is configured as one broadcast domain, there are two broadcast domains. This is not a recommended solution, because both sides of the router attached to the switch and bridge belong to the same broadcast domain. This is not good. On the other hand, the switch can have many broadcast domains defined.

2:

In Figure 2-15, how many Layer 2 and Layer 3 address pairs are used to transmit between Stations 1 and 2?

A:

For Station 1 to communicate with Station 2, two Layer 2 address pairs are needed. One MAC pair is used on the top segment, and the other on the other side of the router. However, only one Layer 3 address pair is needed end to end.

Refer to the network setup in Figure 2-16 to answer Question 3.

3:

What is the problem with the network in Figure 2-16?

A:

Two issues in this network need attention. The most critical problem is that two ports on the Catalyst, which belong to different VLANs, attach to a standard bridge. This merges the two VLANs into a common broadcast domain and defeats the purpose of the Catalyst having two or more broadcast domains.

An additional issue involves Spanning Tree. Although Spanning Tree is not discussed until Chapters 6 and 7, a loop exists in VLAN 1. This might be intentional for resiliency and can be controlled by Spanning Tree. But if unintentional, it can force your network to transmit frames over a less desirable path than you might expect.

4:

If you attach a multiport repeater (hub) to a bridge port, how many broadcast domains are seen on the hub?

A:

Legacy hubs have all ports in the same collision and broadcast domains, regardless of the internetworking device they attach to.

5:

Can a legacy bridge belong to more than one broadcast domain?

A:

Generally, all ports on a legacy bridge belong to the same broadcast domain.