Chp 15

Question 1

Understand the main purpose of the Spanning Tree Protocol in a switched LAN

Answer 1

The main purpose of STP is to prevent switching loops in a network with redundant switched paths

Question 2

Remember the states of STP

Answer 2

The purpose of the blocking state is to prevent the use of looped paths. A port in listening state prepares to forward data frames without populating the MAC address table. A port in learning state populates the MAC address table but doesn’t forward data frames. A port in forwarding state sends and receives all data frames on the bridged port. Also, a port in the disabled state is virtually nonoperational.

Question 3

Remember the command show spanning-tree.

Answer 3

You must be familiar with the command show spanning-tree and how to determine the root bridge of each VLAN. Also, you can use the show spanning-tree summary command to help you get a quick glimpse of your STP network and root bridges

Question 4

Understand what PortFast and BPDU Guard provide.

Answer 4

PortFast allows a port to transition to the forwarding state immediately upon a connection. Because you don’t want other switches connecting to this port, BPDU Guard will shot down a PortFast port if it receives a BPDU.

Question 5

Understand what EtherChannel is and how to configure it.

Answer 5

EtherChannel allows you to bundle links to get more bandwidth, instead of allowing STP to shut down redundant ports. You can configure Cisco’s PAgP or the IEEE version, LACP, by creating a port channel interface and assigning the port channel group number to the interfaces you are bundling.