Spanning Tree Protocol

Front 1

What are the four STP port roles?

Back 1

1) Root
2) Designated
3) Alternate
4) Backup

Front 2

Define a Root port

Back 2

Root—A forwarding port elected for the spanning-tree topology

Front 3

Define a Designated port

Back 3

Designated—A forwarding port elected for every switched LAN segment

Front 4

Define an Alternate port

Back 4

Alternate—A blocked port providing an alternate path to the root port in the spanning tree

Front 5

Define a Backup port

Back 5

Backup—A blocked port in a loopback configuration

Front 6

Define BDPU

Back 6

Switches send and receive spanning-tree frames, called bridge protocol data units (BPDUs), at regular intervals

Front 7

Name the five STP interface states

Back 7

1) Blocking
2) Listening
3) Learning
4) Forwarding
5) Disabled

Front 8

Blocking

Back 8

The interface does not participate in frame forwarding.

Front 9

Listening

Back 9

The first transitional state after the blocking state when the spanning tree determines that the interface should participate in frame forwarding.

Front 10

Learning

Back 10

The interface prepares to participate in frame forwarding.

Front 11

Forwarding

Back 11

The interface forwards frames.

Front 12

Disabled

Back 12

The interface is not participating in spanning tree because of a shutdown port, no link on the port, or no spanning-tree instance running on the port.

Front 13

How does an interface move through the STP states?

Back 13

- From initialization to blocking
- From blocking to listening or to disabled
- From listening to learning or to disabled
- From learning to forwarding or to disabled
- From forwarding to disabled

Front 14

An interface in the BLOCKING state performs these functions

Back 14

- Discards frames received on the interface
- Discards frames switched from another interface for forwarding
- Does not learn addresses
- Receives BPDUs

Front 15

An interface in the LISTENING state performs these functions:

Back 15

- Discards frames received on the interface
- Discards frames switched from another interface for forwarding
- Does not learn addresses
- Receives BPDUs

Front 16

An interface in the LEARNING state performs these functions:

Back 16

- Discards frames received on the interface
-Discards frames switched from another interface for forwarding
-Learns addresses
- Receives BPDUs

Front 17

An interface in the FORWARDING state performs these functions:

Back 17

- Receives and forwards frames received on the interface
- Forwards frames switched from another interface
- Learns addresses
- Receives BPDUs

Front 18

A DISABLED interface performs these functions:

Back 18

- Discards frames received on the interface
- Discards frames switched from another interface for forwarding
- Does not learn addresses
- Does not receive BPDUs

Front 19

What is the default switch priority?

Back 19

32768

Front 20

Which command shows the current state of the spanning tree for this VLAN ID, from the perspective of the switch on which you issue the command?

Back 20

show spantree [vlan_id]

Front 21

Which command provides a summary of connected spanning tree ports by VLAN?

Back 21

show spantree summary

Front 22

Which command shows spanning tree statistical information?

Back 22

show spantree statistics

Front 23

Which command displays whether the spanning tree BackboneFast Convergence feature is enabled?

Back 23

show spantree backbonefast

Front 24

Which command sisplays only the blocked ports?

Back 24

show spantree blockedports

Front 25

Which command shows the path cost for the VLANs on a port?

Back 25

show spantree portvlancost

Front 26

Which command shows the UplinkFast settings?

Back 26

show spantree uplinkfast

Front 27

How do you enables BPDU Guard globally?

Back 27

spanning-tree portfast bpduguard

Front 28

How do you confirm BPDU Guard global configuration?

Back 28

show spanning-tree summary totals

Front 29

How do you Enable EtherChannel Guard?

Back 29

spanning-tree etherchannel guard misconfig

Front 30

How do you verify that EtherChannel guard is enabled?

Back 30

show spanning-tree summary | include EtherChannel

Front 31

How do you enable root guard?

Back 31

Router(config-if)# spanning-tree guard root

Front 32

Name the three STP modes.

Back 32

1) PVST+
2) Rapid PVST+
3)MSTP

Front 33

PVST+

Back 33

This spanning-tree mode is based on the IEEE 802.1D standard and Cisco proprietary extensions. It is the default spanning-tree mode used on all Ethernet, Fast Ethernet, and Gigabit Ethernet port-based VLANs. The PVST+ runs on each VLAN on the switch up to the maximum supported, ensuring that each has a loop-free path through the network.

Front 34

Rapid PVST+

Back 34

This spanning-tree mode is the same as PVST+ except that is uses a rapid convergence based on the IEEE 802.1W standard. To provide rapid convergence, the rapid PVST+ immediately deletes dynamically learned MAC address entries on a per-port basis upon receiving a topology change. By contrast, PVST+ uses a short aging time for dynamically learned MAC address entries.

Front 35

MSTP

Back 35

This spanning-tree mode is based on the IEEE 802.1S standard. You can map multiple VLANs to the same spanning-tree instance, which reduces the number of spanning-tree instances required to support a large number of VLANs. The MSTP runs on top of the RSTP (based on IEEE 802.1W), which provides for rapid convergence of the spanning tree by eliminating the forward delay and by quickly transitioning root ports and designated ports to the forwarding state. You cannot run MSTP without RSTP.

Front 36

How many instances does PVST+ and Rapid PVST+ support?

Back 36

128

Front 37

What is the default STP mode?

Back 37

PVST+

Front 38

How do you configure the port priority for an interface?

Back 38

spanning-tree port-priority priority

For priority, the range is 0 to 240, in increments of 16; the default is 128. Valid values are 0, 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208, 224, and 240. All other values are rejected. The lower the number, the higher the priority.

Front 39

What are the three types of STP timers?

Back 39

1) Hello timer
2) Forward-delay timer
3) Maximum-age timer

Front 40

Hello Timer

Back 40

Controls how often the switch broadcasts hello messages to other switches.

Front 41

Forward-delay timer

Back 41

Controls how long each of the listening and learning states last before the interface begins forwarding.

Front 42

Maximum-age timer

Back 42

Controls the amount of time the switch stores protocol information received on an interface.

Front 43

Displays spanning-tree information on active interfaces only.

Back 43

show spanning-tree active

Front 44

Displays a detailed summary of interface information.

Back 44

show spanning-tree detail

Front 45

Displays a summary of interface states or displays the total lines of the STP state section.

Back 45

show spanning-tree interface [interface-id]