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NETW-152 Midterm > Chapter 15 - Enhanced Switching Technologies > Flashcards

Chapter 15 - Enhanced Switching Technologies Flashcards

1
Q

_____ _____ _____ achieves it’s primary objective of preventing network loops on layer 2 network bridges by monitoring the network to track all links and shut down redundant ones.

A

Spanning Tree Protocol (STP)

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2
Q

STP uses the _____ _____ _____ to first create a topology database and then search out and disable redundant links. \

A

Spanning Tree Algorithm (STA)

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3
Q

With STP running, frames will be forwarded on only _____, _____-_____ links.

A

premium, STP-chosen

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4
Q

The _____ _____ is the bridge with the lowest and, therefore, the best bridge ID.

A

Root Bridge

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5
Q

The switches within an STP network _____ a root bridge.

A

elect

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6
Q

Once the root bridge has been elected, all other bridges must create a _____ path to it.

A

single

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7
Q

the port with the best path to the root bridge is called the _____ _____.

A

Root Port

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8
Q

_____-_____ _____ exchange BPDUs with all the other bridges and update the STP topology database on all switches. This prevents loops and helps to defend against link failures.

A

Non-Root Bridges

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9
Q

Each switch compares the parameters in the _____ _____ _____ _____ that it send to a neighbor with the parameters in the _____ _____ _____ _____ that it receives from other neighbors.

A

Bridge Protocol Data Unit (BPDU)

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10
Q

Inside the BPDU is the _____ _____.

A

Bridge ID

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11
Q

The _____ _____ is how STP keeps track of all of the switches on the network.

A

Bridge ID

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12
Q

The bridge ID is determined by a combination of the _____ _____, which is 32,768 by default on all Cisco switches, and the _____ _____ _____.

A

bridge priority, base MAC address

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13
Q

Most networks benefit by forcing a specific bridge or switch to be the root bridge by setting it’s _____ _____ lower than the default value.

A

bridge priority

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14
Q

_____ _____ determines the best path when multiple links are used between 2 switches.

A

Port Cost

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15
Q

the cost of a link is determined by the _____ of a link.

A

bandwidth

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16
Q

_____ _____ is calculated for each unique path by adding the individual port costs encountered on the way to the root bridge.

A

Path Cost

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17
Q

STP uses _____ to determine how a port on a switch will act within the spanning-tree algorithm.

A

Roles

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18
Q

The _____ _____ is the link with the lowerst path cost to the root bridge.

A

Root Port

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19
Q

When multiple links connect to the same device, the port connected to the _____ _____ _____ on the upstream switch will be the one that’s used.

A

lowest port number

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20
Q

The root bridge can never have a _____ _____ designation, while ever other switch in a network must have one.

A

Root Port

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21
Q

A _____ _____ is one that’s been determined to have the best (lowest) cost to get to on a given network segment, compared to other ports on that segment.

A

Designated Port

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22
Q

A designated port will be marked as a _____ _____.

A

Forwarding Port

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23
Q

You can only have _____ forwarding port per network segment.

A

one

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24
Q

_____ _____ ports are basically the ones left over after the root ports and designated ports have been determined.

A

Non-Designated

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25
Q

Non-designated ports are put into _____ or _____ discarding mode - they DO NOT forward frames.

A

blocking, discarding

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26
Q

A _____ _____ forwards frames and will be either a root port or a designated port.

A

Forwarding Port

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27
Q

While it will never forward frames in order to prevent loops, a _____ _____ will still always listen to the BPDU frames from neighbor switches and will drop any and all other frames received.

A

Blocked Port (this term is specific to 801.d)

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28
Q

This is the term used with 802.1w and is analogous to the term “blocking port” used with 802.1d.

A

Alternate Port or Backup Port

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29
Q

The ports on a bridge or switch running IEEE 802.1d STP can transition through _____ different states.

A

5

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30
Q

A port in the _____ _____ state doesn’t participate in frame forwarding or STP.

A

administratively disabled

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31
Q

The purpose of the _____ state is to prevent the use of looped paths. All ports are in the _____ state by default when the switch is powered up.

A

Blocking

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32
Q

A port in the _____ state listens to BPDUs to make sure no loops occur on the network before passing data frames. It prepares to forward data frames without populating the MAC address table.

A

Listening

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33
Q

A port in _____ state listens to BPDUs and learns all paths in the switched network. It populates the MAC address table but still doesn’t forward data frames.

A

Learning

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34
Q

_____ _____ refers to the time it takes to transition a port from listening to learning mode, or from learning to forwarding mode.

A

Forward Delay

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35
Q

What is the length of the Forward Delay set to be default on Cisco switches, and the output of which command shows this setting.

A

15 seconds, show spanning-tree

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36
Q

If a port is still a designated or root port at the end of the learning state, it will enter the _____ state.

A

Forwarding

37
Q

Switch ports are most often in either the _____ or _____ state.

A

blocking, forwarding

38
Q

Once a switch determines the best patj to the root bridge for it’s root port and any designated ports, and other redundant ports will be in _____ mode.

A

Blocking

39
Q

If a switch determines that a blocked port should become the designated or root port because of a topology change, it will go into _____ mode and check all BPDUs it receives to make sure it won’t create a loop once the port moves into forwarding mode.

A

Listening

40
Q

_____ occurs when all ports on bridges and switches have transitioned to either forwarding or blocking modes. No data will be forwarded until _____ is complete. _____ is vital because it ensures that all devices have a coherent database.

A

Convergence

41
Q

What is the port cost for a 10 Mb/s link?

A

100

42
Q

What is the port cost for a 100 Mb/s link?

A

19

43
Q

What is the port cost for a 1000 Mb/s link?

A

4

44
Q

What is the port cost for a for a 10,000 Mb/s link?

A

2

45
Q

Every port on the _____ _____ is a designated, or forwarding, port for a segment.

A

Root Bridge

46
Q

The bridge ID is _____ bytes long and includes both the priority and the MAC address of the device.

A

8

47
Q

If 2 bridges or switches happen to have the same priority value, the _____ _____ becomes the tiebreaker for figuring out which one has the lowest bridge ID.

A

MAC address

48
Q

Prior to the election of the root bridge, BPDUs are sent every _____ seconds out all active ports on a bridge/switch by default, and they’re received and processed by all bridges.

A

2

49
Q

_____ _____ is the original standard for bridging and STP, which is really slow but requires very little bridge resources.

A

IEEE 802.1d

50
Q

IEEE 802.1d is also referred to as _____ _____ _____.

A

Common Spanning Tree (CST)

51
Q

_____ is the Cisco proprietary enhancement for STP that provides a separate 802.1d spanning-tree instance for each VLAN. While it is just as slow as the CST protocol, it also provides more than one root bridge and uses more resources than CST.

A

PVST+

52
Q

_____ _____ or _____ _____ _____ _____ enhanced the BPDU exchange and paved the way for much faster network convergence but still only allows for one root bridge per network. The bridge resources used with this protocol are higher than CST’s but less that PVST+

A

IEEE 8.2/1w, Rapid Spanning-Tree Protocol (RPST)

53
Q

_____ is Cisco’s version of RSTP that also uses PVST+ and provides a separate instance of 802.1w per VLAN. While it gives us really fast convergence times and optimal traffic flow, it requires the most CPU and memory of all.

A

Rapid PVST+

54
Q

What is the default convergence time for PVST+?

A

50 seconds

55
Q

As it relates to PVST+, in order to have a root bridge created per STP instance (which in the case of PVST+ is per VLAN), the BPDU is modified to include an additional field. How long is the extended system ID (VLAN ID)?

A

12 bits

56
Q

True or False: IEEE 802.1w does not offer backward compatibility.

A

False

57
Q

True or False: RPST (802.11w) requires the use of the same delay timers as CST (802.1d)

A

False

58
Q

RTSP has _____ states of transition where CST has 5.

A

3 (discarding, learning, forwarding)

59
Q

To choose the switch that will _____ on the segment, we select the switch with the lowest accumulated path cost to the root bridge.

A

forward

60
Q

When choosing which switch will forward on a segment, if there is a tie on the accumulated path cost from both switches to the root bridge, we use the _____ _____.

A

Bridge ID

61
Q

The default port priority is _____, but it can be manually changed.

A

32

62
Q

When choosing which switch will forward on a segment, if there are 2 links between switches and the bridge ID and priority are tied, the port with the _____ _____ will be chosen.

A

lowest number

63
Q

Which command is used to verify spanning-tree on a Cisco switch?

A

show spanning-tree

64
Q

What can be determined from the output of the show spanning-tree command?

A

the root bridge, priorities, and root, designated, and non-designated/blocking/discarding ports.

65
Q

To find out which is the root bridge, issue the _____ _____ _____ command, find your root port, and then use the _____ _____ _____ command.

A

show spanning tree, show cdp neighbors

66
Q

To force a bridge into the root bridge role for a particular VLAN by changing it’s priority, you can issue the _____-_____ _____ _____ _____ _____ command in global configuration mode.

A

spanning-tree vlan priority

67
Q

To force a bridge into the root bridge role for a particular VLAN without having to change it’s priority, you can issue the _____-_____ _____ _____ _____ _____ command in global configuration mode.

A

spanning-tree vlan root primary

68
Q

To enable RPST on a Cisco switch, you can issue the _____-_____ _____ _____-_____ command in global configuration mode.

A

spanning-tree mode rapid-pvst

69
Q

If you have a server or other devices connected into your switch that you’re totally sure won’t create a switching loop if STP is disabled, you can use a Cisco proprietary extension to the 802.1d standard called _____ on these ports.

A

PortFast

70
Q

In global configuration mode, how do you enable portfast bdpu filter?

A

S1(config)#spanning-tree portfast bpdufilter

71
Q

In global configuration mode, how do you enable portfast bpdu guard?

A

S1(config)#spanning-tree portfast bpduguard

72
Q

In global configuration mode, how do you enable portfast by default on all access ports?

A

S1(config)#spanning-tree portfast default

73
Q

From interface configuration mode, how can you enable portfast on the interface even in trunk mode?

A

S1(config-if)#spanning-tree portfast trunk

74
Q

From interface configuration mode, how can you disable portfast on the interface?

A

S1(config-if)#spanning-tree portfast disable

75
Q

If you turn on PortFast for a switch port, it’s a really good idea to turn on _____ _____ as well because if a switch port that has PortFast enabled receives a BPDU on that port, it will place the port into error disabled (shutdown) state, effectively preventing anyone from accidentally connecting another switch or hub port into a switch port configured with PortFast.

A

BPDU Guard

76
Q

you would only configure the spanning-tree bpduguard enable command on your _____ layer switches—switches where users are directly connected.

A

access

77
Q

The Cisco version of the port channel negotiation protocol is called the _____ _____ _____.

A

Port Aggregation Protocol (PAgP)

78
Q

The IEEE 802.3ad standard of the port channel negotiation protocol is called the _____ _____ _____ _____.

A

Link Aggregation Control Protocol (LACP)

79
Q

Cisco EtherChannel allows us to bundle up to _____ ports active between switches. The links must have the same speed, duplex setting, and VLAN configuration—in other words you can’t mix interface types and configurations into the same bundle.

A

8

80
Q

_____ _____ to combining two-to-eight Fast Ethernet or two-Gigabit Ethernet ports together between two switches into one aggregated logical link to achieve more bandwidth and resiliency

A

Port channeling

81
Q

_____ is Cisco’s proprietary term for port channeling.

A

EtherChannel

82
Q

_____ is a Cisco proprietary port channel negotiation protocol that aids in the automatic creation for EtherChannel links. All links in the
bundle must match the same parameters (speed, duplex, VLAN info), and when _____ identifies matched links, it groups the links into an EtherChannel. This is then added to STP as a single bridge port. At this point, _____’s job is to send packets every 30 seconds to manage the link for consistency, any link additions, and failures.

A

Port Aggregation Protocol (PAgP)

83
Q

_____-_____ is a command on Ethernet interfaces used to add the specified interface to a single EtherChannel. The number following this command is the port channel ID.

A

Channel-group

84
Q

The command _____ _____-_____ creates the bundled interface. Ports can be added to this interface with the channel-group command. Keep in mind that the interface number must match the group number.

A

Interface port-channel

85
Q

You can enable your channel-group for each channel by setting the channel mode for each interface to either active or passive if using _____.

A

Link Aggregation Control Protocol (LACP)

86
Q

When a port is configured in _____ mode, it will respond to the LACP packets it receives, but it won’t initiate an LACP negotiation.

A

passive

87
Q

When a port is configured for _____ mode, the port initiates negotiations with other ports by sending LACP packets.

A

active

88
Q

You can enable your channel-group for each channel by setting the channel mode for
each interface to either _____ or _____ if using LACP.

A

active, passive

89
Q

the _____ _____ _____-_____ command shows information about a specific port channel
interface.

A

show etherchannel port-channel

NETW-152 Midterm (1 decks)

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