Section 6: Spanning Tree Protocol

Question 1

STP

Answer 1

802.1d - Spanning Tree Protocol - Permits redundant links between switches and prevents looping of network traffic.

Question 2

SPB

Answer 2

Shortest Path Bridging - Used instead of STP for larger network environments. (Not a deep discussion for exam)

Question 3

Broadcast Storm

Answer 3

Multiple copies of frames are being forwarded back and forth.

Occurs if network does not have the Spanning Tree Protocol.

Question 4

Root Bridge

Answer 4

Used by STP. Switch elected as reference point for the spanning tree. Bridge with the lowest Bridge Id (BID) -Made up of priority value and MAC address.

Question 5

Non-Root Bridge

Answer 5

All other switches in an STP topology.

Question 6

Root Port

Answer 6

Assigned on every non-root bridge and is the closes to the root-bridge in terms of cost.

Question 7

Designated Port

Answer 7

Port closes to the root bridge for each network segment. (All ports on the root bridge are considered designated ports.

Question 8

Non-Designated Port

Answer 8

Ports that block traffic to create loop-free topology

Question 9

Port States

Answer 9

▪ Non-designated ports do not forward traffic during normal operation, but do receive bridge protocol data units (BPDUs)
▪ If a link in the topology goes down, the non-designated port detects the failure and determines whether it needs to transition to a forwarding state
▪ To get to the forwarding state, though, it has to transition through four states (Blocking, Listening, Learning, Forwarding)

Question 10

Link Cost

Answer 10

Faster cables have lower cost and slower cables have a higher cost.