6.4.4 Module Quiz – Etherchannel (Answers)

6.4.4 Module Quiz – Etherchannel Answers

1. An EtherChannel link using LACP was formed between two switches, S1 and S2. While verifying the configuration, which mode combination could be utilized on both switches?​

  • S1-passive and S2-passive
  • S1-on and S2-active
  • S1-on and S2-passive
  • S1-passive and S2-active

Explanation: An EtherChannel link will be formed using LACP when both switches are in on mode or in active mode, or when one of them is in passive mode and the other is in active mode.

2. When a range of ports is being configured for EtherChannel, which mode will configure PAgP so that it initiates the EtherChannel negotiation?

  • active
  • desirable
  • passive
  • auto

Explanation: The command channel-group mode active enables LACP unconditionally, and the command channel-group mode passive enables LACP only if the port receives an LACP packet from another device. The command channel-group mode desirable enables PAgP unconditionally, and the command channel-group mode auto enables PAgP only if the port receives a PAgP packet from another device.

3. Which three interface parameters must match for an EtherChannel to form? (Choose three.)

  • PortFast mode
  • spanning-tree state
  • allowed VLANs
  • native VLAN
  • EtherChannel mode
  • trunking mode

Explanation: There are some EtherChannel modes that can be different and an EtherChannel will form, such as auto/desirable and active/passive. A port that is currently in the spanning tree blocking mode or has been configured for PortFast can still be used to form an EtherChannel.

4. What are three advantages of using EtherChannel technology? (Choose three.)

  • Configuration tasks can be done on the EtherChannel interface.
  • A spanning tree recalculation is not required when a single link within the channel goes down.
  • The Spanning Tree Protocol shuts down the unused interfaces in the bundle to avoid loops.
  • There is no need to upgrade links to faster connections to increase bandwidth.
  • EtherChannel uses multiple logical links to provide redundancy.
  • Load balancing is not needed with EtherChannel.

Explanation: Most configuration tasks can be done on the EtherChannel interface, rather than on individual ports. Existing ports can be used, eliminating the need to upgrade ports to faster speeds. Spanning Tree Protocol runs on EtherChannel links in the same manner as it does on regular links, but it does not recalculate when an individual link within the channel goes down. EtherChannel also supports load balancing.

5. A network administrator is configuring an EtherChannel link between two physical ports on a switch. Which statement describes the result when one of the physical ports fails?

  • An STP recalculation is needed.
  • The EtherChannel link fails.
  • The EtherChannel stops transmitting data until it is restarted.
  • The EtherChannel continues transmitting data with reduced bandwidth.

Explanation: An EtherChannel is seen as one logical connection. The loss of one physical link within the channel does not create a change in the topology and therefore a spanning tree recalculation is not required. When one of the member ports in the EtherChannel fails, the EtherChannel link remains functional, although its overall throughput decreases because of a lost link within the EtherChannel.

6. When EtherChannel is implemented, multiple physical interfaces are bundled into which type of logical connection?

  • port channel
  • loopback
  • VLAN interface
  • interface range

Explanation: When EtherChannel is being configured, the first step is to specify what physical ports will be used in an EtherChannel group. The second step is to create the logical EtherChannel port channel interface which contains the group of physical interfaces.

7. When a range of ports is being configured for EtherChannel by the use of PAgP, which mode will form the bundled channel only if the port receives PAgP packets from another device?

  • desirable
  • active
  • auto
  • passive

Explanation: The command channel-group mode active enables LACP unconditionally, and the command channel-group mode passive enables LACP only if the port receives an LACP packet from another device. The command channel-group mode desirable enables PAgP unconditionally, and the command channel-group mode auto enables PAgP only if the port receives a PAgP packet from another device.

8. Which two load balancing methods can be implemented with EtherChannel technology? (Choose two.)

  • source IP to destination IP
  • source MAC to destination MAC
  • destination IP to destination MAC
  • destination MAC to source MAC
  • destination IP to source IP
  • destination MAC to destination IP

Explanation: Source MAC to destination MAC load balancing and source IP to destination IP load balancing are two implementation methods used in EtherChannel technology.

9. Which function is provided by EtherChannel?

  • enabling traffic from multiple VLANs to travel over a single Layer 2 link
  • spreading traffic across multiple physical WAN links
  • dividing the bandwidth of a single link into separate time slots
  • creating one logical link by using multiple physical links between two LAN switches

Explanation: EtherChannel technology allows the grouping, or aggregating, of several Fast Ethernet or Gigabit switch ports into one logical channel.

10. Which statement is true about EtherChannel technology?

  • All configuration tasks must be done on the individual ports in the EtherChannel link.
  • STP does not run on redundant EtherChannel links.
  • EtherChannel uses existing switch ports.
  • Links must be upgraded to support EtherChannel.

Explanation: EtherChannel relies on existing switch ports, so there is no need to upgrade the links. Some configuration tasks are done on individual ports and some configuration tasks are done on the EtherChannel group. STP operates on EtherChannel in the same manner as it does on other redundant links.

11. Which two mode combinations would result in the successful negotiation of an EtherChannel? (Choose two.)

  • active; on
  • passive; auto
  • desirable; desirable
  • desirable; active
  • active; passive
  • auto; auto

Explanation: The combinations of modes that will form an EtherChannel are as follows: on/on, active/passive, active/active, desirable/auto, and desirable/desirable.

12. Which two protocols are link aggregation protocols? (Choose two.)

  • EtherChannel
  • STP
  • PAgP
  • 802.3ad
  • RSTP

Explanation: The two protocols that can be used to form an EtherChannel are PAgP (Cisco proprietary) and LACP, also know as IEEE 802.3ad. STP (Spanning Tree Protocol) or RSTP (Rapid Spanning Tree Protocol) is used to avoid loops in a Layer 2 network. EtherChannel is the term that describes the bundling of two or more links that are treated as a single link for spanning tree and configuration.

13. When a range of ports is being configured for EtherChannel, which mode will configure LACP so that it initiates the EtherChannel negotiation?

  • active
  • auto
  • desirable
  • passive

Explanation: The command channel-group mode active enables LACP unconditionally, and the command channel-group mode passive enables LACP only if the port receives an LACP packet from another device. The command channel-group mode desirable enables PAgP unconditionally, and the command channel-group mode auto enables PAgP only if the port receives a PAgP packet from another device.

14. What will happen if a network administrator puts a port that is part of an EtherChannel bundle into a different VLAN than the other ports in that bundle?

  • The EtherChannel will fail.
  • The EtherChannel bundle will stay up if the ports were configured with no negotiation between the switches to form the EtherChannel.
  • The EtherChannel bundle will stay up if either PAgP or LACP is used.
  • The EtherChannel bundle will stay up only if LACP is used.
  • The EtherChannel bundle will stay up only if PAgP is used.

Explanation: All ports in an EtherChannel bundle must either be trunk ports or be access ports in the same VLAN. If VLAN pruning is enabled on the trunk, the allowed VLANs must be the same on both sides of the EtherChannel.

15. When a range of ports is being configured for EtherChannel, which mode will configure LACP on a port only if the port receives LACP packets from another device?

  • auto
  • passive
  • desirable
  • active

Explanation: The command channel-group mode active enables LACP unconditionally, and the command channel-group mode passive enables LACP only if the port receives an LACP packet from another device. The command channel-group mode desirable enables PAgP unconditionally, and the command channel-group mode auto enables PAgP only if the port receives a PAgP packet from another device.

16. There has been an increase in network traffic between two Catalyst 2960 switches, and their FastEthernet trunk link has reached its capacity. How can traffic flow be improved?

  • Add routers between the switches to create additional broadcast domains.
  • Bundle physical ports using EtherChannel.
  • Configure smaller VLANs to decrease the size of the collision domain.
  • Increase the speed of the ports using the bandwidth command.

Explanation: Increasing the link speed does not scale very well. Adding more VLANs will not reduce the amount of traffic that is flowing across the link. Inserting a router between the switches will not improve congestion.

17. Which statement is true regarding the use of PAgP to create EtherChannels?

  • It increases the number of ports that are participating in spanning tree.
  • It is Cisco proprietary.
  • It mandates that an even number of ports (2, 4, 6, etc.) be used for aggregation.
  • It requires full duplex.
  • It requires more physical links than LACP does

Explanation: PAgP is used to automatically aggregate multiple ports into an EtherChannel bundle, but it works only between Cisco devices. LACP can be used for the same purpose between Cisco and non-Cisco devices. PAgP must have the same duplex mode at both ends and can use two ports or more. The number of ports depends on the switch platform or module. An EtherChannel aggregated link is seen as one port by the spanning tree algorithm.

18. Which combination of channel-group modes will establish an EtherChannel?

  • Switch 1 set to auto; switch 2 set to auto.
  • Switch 1 set to auto; switch 2 set to on.
  • Switch 1 set to desirable; switch 2 set to desirable.
  • Switch 1 set to on; switch 2 set to desirable.

Explanation: Switch 1 and switch 2 will establish an EtherChannel if both sides are set to desirable, because both sides will negotiate the link. A channel can also be established if both sides are set to on, or if one side is set to auto and the other to desirable. Setting one switch to on will prevent that switch from negotiating the formation of an EtherChannel bundle.

19. Which interface configuration command will enable the port to initiate an LACP EtherChannel?

  • channel-group mode active
  • channel-group mode auto
  • channel-group mode desirable
  • channel-group mode on
  • channel-group mode passive

Explanation: The channel-group mode active command enables LACP unconditionally, and the channel-group mode passive command enables LACP only if the port receives an LACP packet from another device. The channel-group mode desirable command enables PAgP unconditionally, and the channel-group mode auto command enables PAgP only if the port receives a PAgP packet from another device.

20. Which interface configuration command will enable the port to establish an EtherChannel only if it receives PAgP packets from the other switch?

  • channel-group mode active
  • channel-group mode auto
  • channel-group mode desirable
  • channel-group mode on
  • channel-group mode passive

Explanation: The channel-group mode active command enables LACP unconditionally, and the channel-group mode passive command enables LACP only if the port receives an LACP packet from another device. The channel-group mode desirable command enables PAgP unconditionally, and the channel-group mode auto command enables PAgP only if the port receives a PAgP packet from another device.

21. Which statement describes a characteristic of EtherChannel?

  • It can combine up to a maximum of 4 physical links.
  • It can bundle mixed types of 100 Mbps and 1 Gbps Ethernet links.
  • It consists of multiple parallel links between a switch and a router.
  • It is made by combining multiple physical links that are seen as one link between two switches.

Explanation: An EtherChannel is formed by combining multiple (same type) Ethernet physical links so they are seen and configured as one logical link. It provides an aggregated link between two switches. Currently each EtherChannel can consist of up to eight compatibly configured Ethernet ports.

22. What are two advantages of using LACP? (Choose two.)

  • LACP allows automatic formation of EtherChannel links.
  • LACP allows use of multivendor devices.
  • LACP decreases the amount of configuration that is needed on a switch for EtherChannel.
  • LACP eliminates the need for the Spanning Tree Protocol.
  • LACP increases redundancy to Layer 3 devices.
  • LACP provides a simulated environment for testing link aggregation.

Explanation: LACP is part of an IEEE specification (802.3ad) that enables several physical ports to automatically be bundled to form a single EtherChannel logical channel. LACP allows a switch to negotiate an automatic bundle by sending LACP packets to the peer. It performs a function similar to PAgP with Cisco EtherChannel, but it can be used to facilitate EtherChannels in multivendor environments. Cisco devices support both PAgP and LACP configurations.

23. Which three settings must match in order for switch ports to form an EtherChannel? (Choose three.)

  • Non-trunk ports must belong to the same VLAN.
  • Port security violation settings on interconnecting ports must match.
  • The duplex settings on interconnecting ports must match.
  • The port channel group number on interconnecting switches must match.
  • The SNMP community strings must match.
  • The speed settings on interconnecting ports must match.

Explanation: Speed and duplex settings must match for all interfaces in an EtherChannel. All interfaces in the EtherChannel must be in the same VLAN if the ports are not configured as trunks. Any ports may be used to establish an EtherChannel. SNMP community strings and port security settings are not relevant to EtherChannel.

Subscribe
Notify of
guest

1 Comment
Inline Feedbacks
View all comments
Kai
Kai
1 year ago

Thanks!!

1
0
Would love your thoughts, please comment.x
()
x