Switching

Question 1

802.3z is the standard for what?

Answer 1

1000Mb/s Gigabit Ethernet

Question 2

802.3u is the standard for what?

Answer 2

100Mb/s Fast Ethernet

Question 3

Hubs run at what duplex

Answer 3

Half

Question 4

Ethernet ports run at what speed

Answer 4

10 Mb/s - Not to be confused with fast ethernet

Question 5

Fast ethernet ports run at what speed

Answer 5

100 Mb/s

Question 6

How to identify excessive noise problems on a switch

Answer 6

Look for CRC errors after executing the show interfaces command

Question 7

How to troubleshoot collisions

Answer 7

Collisions can be seen after executing the show interfaces command. Possible causes are defective nics in a host or duplex mismatch.

Question 8

How to troubleshoot late collisions.

Answer 8

A late collision happens after the 64th byte. Possible causes are duplex mismatches or cables that are to long.

Question 9

How to troubleshoot duplex mismatches.

Answer 9

Look for collisions and runts after executing the show interfaces command. Use the show interfaces status command to see the current duplex and speed settings of the individual ports.

Question 10

How to troubleshoot speed mismatches.

Answer 10

Links will show down. Use the show interfaces status command to see the current duplex and speed settings of the individual ports.

Question 11

How to troubleshoot broadcast storms.

Answer 11

Broadcast storms can be caused by loops between switches or having both ends of a cable plugged into the same switch. You may see high CPU utilization or a high collision count. Use the show interfaces command to see collisions and the show processes command to see the CPU utilization. Use wireshark to capture packets and evaluate the number of broadcast.

Question 12

As a part of standard security what should be done with unused switch ports?

Answer 12

They should be disabled with the shutdown command.