CCNA2 - Module 5&6

Question 1

is an important part of the hierarchical design for eliminating single points of failure and preventing disruption of network services to users.

Answer 1

Redundancy

Question 2

True/False:
Ethernet LANs require a loop-free topology with a single path between any two devices.

Answer 2

True

Question 3

is a loop-prevention network protocol that allows for redundancy while creating a loop-free Layer 2 topology.
logically blocks physical loops in a Layer 2 network, preventing frames from circling the network forever

Answer 3

Spanning Tree Protocol (STP)

Question 4

compensates for a failure in the network by recalculating and opening up previously blocked ports.

Answer 4

STP

Question 5

provides multiple network services by eliminating the possibility of a single point of failure.

Answer 5

Path redundancy

Question 6

STP was developed specifically as a loop prevention mechanism for ________________________

Answer 6

Layer 2 Ethernet

Question 7

is when the switch does not have the destination MAC address in its MAC address table and must forward the frame out all ports, except the ingress port.

Answer 7

unknown unicast frame

Question 8

is an abnormally high number of broadcasts overwhelming the network during a specific amount of time.
can disable a network within seconds by overwhelming switches and end devices. Broadcast storms can be caused by a hardware problem such as a faulty NIC or from a Layer 2 loop in the network.

Answer 8

broadcast storm

Question 9

To prevent these issues from occurring in a redundant network, some type of ___________ must be enabled on the switches.

Answer 9

spanning tree

Question 10

T/F:
Spanning tree is enabled manually on Cisco switches

Answer 10

False
it is enabled by default

Question 11

STP is based on an algorithm invented by __________ while working for Digital Equipment Corporation, and published in the 1985 paper "An Algorithm for Distributed Computation of a Spanning Tree in an Extended LAN.”

Answer 11

Radia Perlman

Question 12

creates a loop-free topology by selecting a single root bridge where all other switches determine a single least-cost path.

Answer 12

spanning tree algorithm (STA)

Question 13

-is the interval between BPDUs. The default is 2 seconds but can be modified to between 1 and 10 seconds.

Answer 13

Hello Timer

Question 14

• is the time that is spent in the listening and learning state. The default is 15 seconds but can be modified to between 4 and 30 seconds.

Answer 14

Forward Delay Timer

Question 15

• is the maximum length of time that a switch waits before attempting to change the STP topology. The default is 20 seconds but can be modified to between 6 and 40 seconds.

Answer 15

Max Age Timer

Question 16

versions of STP, there is a root bridge elected for each spanning tree instance. This makes it possible to have different root bridges for different sets of VLANs.

Answer 16

Per-VLAN Spanning Tree (PVST)

Question 17

: This is the original IEEE 802.1D version (802.1D-1998 and earlier) that provides a loop-free topology in a network with redundant links. Also called Common Spanning Tree (CST), it assumes one spanning tree instance for the entire bridged network, regardless of the number of VLANs.

Answer 17

STP

Question 18

: is a Cisco enhancement of STP that provides a separate 802.1D spanning tree instance for each VLAN configured in the network.
* supports PortFast, UplinkFast, BackboneFast, BPDU guard, BPDU filter, root guard, and loop guard.

Answer 18

Per-VLAN Spanning Tree (PVST+)

Question 19

: This is an updated version of the STP standard, incorporating IEEE 802.1w.

Answer 19

802.1D-2004

Question 20

or IEEE 802.1w is an evolution of STP that provides faster convergence than STP.

Answer 20

Rapid Spanning Tree Protocol (RSTP)

Question 21

: This is a Cisco enhancement of RSTP that uses PVST+ and provides a separate instance of 802.1w per VLAN. Each separate instance supports PortFast, BPDU guard, BPDU filter, root guard, and loop guard.

Answer 21

Rapid PVST+

Question 22

is an IEEE standard inspired by the earlier Cisco proprietary Multiple Instance STP (MISTP) implementation. MSTP maps multiple VLANs into the same spanning tree instance.

Answer 22

Multiple Spanning Tree Protocol (MSTP)

Question 23

is the Cisco implementation of MSTP, which provides up to 16 instances of RSTP and combines many VLANs with the same physical and logical topology into a common RSTP instance. Each instance supports PortFast, BPDU guard, BPDU filter, root guard, and loop guard.

Answer 23

Multiple Spanning Tree (MST)

Question 24

supersedes the original 802.1D while retaining backward compatibility

Answer 24

RSTP (IEEE 802.1w)

Question 25

EtherChannels can be formed through negotiation using one of two protocols, ___________-. These protocols `allow ports with similar characteristics to form a channel` through dynamic negotiation with adjoining switches.

Answer 25

**Port Aggregation Protocol (PAgP) or Link Aggregation Control Protocol (LACP)**

Question 26

is a Cisco-proprietary protocol that `aids in the` **automatic creation** `of EtherChannel links`.

Answer 26

**PAgP (pronounced “Pag - P”)**

Question 27

helps `create the EtherChannel link` by detecting the configuration of each side and ensuring that links are compatible so that the EtherChannel link can be enabled when needed.

Answer 27

**PAgP**

Question 28

The modes for PAgP as follows:

Answer 28

**On** - This mode forces the interface to channel without PAgP. Interfaces configured in the on mode do not exchange PAgP packets. **PAgP desirable** - This PAgP mode places an interface in an active negotiating state in which the interface initiates negotiations with other interfaces by sending PAgP packets. **PAgP auto** - This PAgP mode places an interface in a passive negotiating state in which the interface responds to the PAgP packets that it receives but does not initiate PAgP negotiation. The modes must be compatible on each side. If one side is configured to be in auto mode, it is placed

Question 29

is part of an `IEEE specification (802.3ad)` that allows `several physical ports` to be bundled to form a single logical channel.

Answer 29

**Link Aggregation Control Protocol (LACP)**

Question 30

provides the same negotiation benefits as PAgP. It helps `create the EtherChannel link` by detecting the configuration of each side and making sure that they are compatible so that the EtherChannel link can be enabled when needed

Answer 30

**Link Aggregation Control Protocol (LACP)**

Question 31

The modes for LACP are as follows:

Answer 31

**On** - This mode forces the interface to channel without LACP. Interfaces configured in the on mode do not exchange LACP packets. **LACP active** - This LACP mode places a port in an active negotiating state. In this state, the port initiates negotiations with other ports by sending LACP packets. **LACP passive** - This LACP mode places a port in a passive negotiating state. In this state, the port responds to the LACP packets that it receives but does not initiate LACP packet negotiation.

Question 32

**The following guidelines and restrictions are useful for configuring EtherChannel:**

Answer 32

* **EtherChannel support** - All Ethernet interfaces must support EtherChannel with no requirement that interfaces be physically contiguous. * **Speed and duplex** - Configure all interfaces in an EtherChannel to operate at the same speed and in the same duplex mode. * **VLAN match** - All interfaces in the EtherChannel bundle must be assigned to the same VLAN or be configured as a trunk (shown in the figure). * **Range of VLANs** - An EtherChannel supports the same allowed range of VLANs on all the interfaces in a trunking EtherChannel. If the allowed range of VLANs is not the same, the interfaces do not form an EtherChannel, even when they are set to auto or desirable mode.