2.3 Ethernet Switching

Question 1

What value is added to in 802.1Q, or trunking protocol?

Answer 1

VLAN ID

Question 2

What feature in a network switch allows a group of ports to each be a separate broadcast domain?

Answer 2

VLANs

Question 3

What terms help describe 802.1ad, or Link Aggregation Control Protocol (LACP)?

Answer 3

Link Aggregation Group (LAG), Port Bonding, Link Bonding, NIC Teaming, or EtherChannel.

Question 4

What does 802.3X, or Pause Frame do?

Answer 4

A pause frame sends a message to another device to tell it to pause before sending more traffic when a switch gets overloaded.

Question 5

What function do enterprise switches use to send exact copies of messages passing from one port to another without interrupting the flow of traffic?
This function is used for troubleshooting, security inspection, and analysis.

Answer 5

Port Mirroring

Question 6

What are the two IEEE standards for Power over Ethernet (PoE)?

Answer 6

802.3af: PoE @15.4W
802.3at: PoE+ @32.4W

Question 7

What protocol uses bridge protocol data units to detect and prevent bridging loops in a LAN topology?

Answer 7

802.1D or Spanning Tree Protocol

Question 8

What two values are checked first before evaluating other criteria in the election process of a 802.1D, or STP, root bridge?

Answer 8

Priority, if multiple switches have the same priority the lowest MAC address is used instead.

Question 9

What are the STP port states?

Answer 9

Blocking: 20s- Receives BPDUs
Listening: 15s- Sends BPDUs
Learning: 15s- Learns MACs
Forwarding: Forwards Frames

Question 10

In shared medium ethernet, what are the three parts of CSMA/CD?

Answer 10

Carrier Sense: Listen when free
Multiple Access: Talk when free
Collision Detection: back-off if collision occurs (each device starts an independent randomized back-off timer)