Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CCNP Core > Chap 2 - Spanning Tree Protocol > Flashcards

Chap 2 - Spanning Tree Protocol Flashcards

1
Q

What happens on a port in Disabled state?

A

It is admin’ed down.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What happens on a port in Blocking state?

A
  • BPDUs: Receive only
  • Modify MAC table: No
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens on a port in Listening state?

A
  • BPDUs: Sends and receives
  • Modify MAC table: No
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens on a port in Learning state?

A
  • BPDUs: Send and receive
  • Modify MAC table: Yes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens on a port in Forwarding state?

A
  • BPDUs: Sends and receives
  • Modify MAC table: Yes
  • Forwarding: Yes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 3 802.1D port types?

A
  • Root Port (RP)
  • Designated Port (DP)
  • Blocking Port
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How many RPs are there on a switch?

A

No more than 1 RP per VLAN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the Destination MAC of a BPDU?

A

01:80:c2:00:00:00

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 2 types of BPDUs?

A
  • Configuration BPDU
  • Topology Change Notification (TCN) BPDU
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What 4 things does a Configuration BPDU do?

A
  • Identifies the Root Bridge
  • Identifies RP
  • Identifies DP
  • Identifies Blocking Ports
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 7 fields in a Configuration BPDU?

A
  • STP Type
  • Root Path Cost
  • Root Bridge Identifier
  • Local Bridge Identifier
  • Hello Timer
  • Forward Delay Timer
  • Max Age
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does a Topology Change Notification (TCN) BPDU signify?

A

Communicates changes in the Layer 2 topology to other switches.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the Max Age time?

A

If a switch loses communication with the generating switch of a BPDU the Max Age time is the length of time a switch considers that BPDU to be valid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the default Max Age time?

A

20 seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How is the Root Bridge determined?

A
  • The bridge with the lowest Priority
  • if there is a tie then the bridge with the lowest MAC address
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the default Priority?

A

32768 + sys-id-ext

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the sys-id-ext?

A

A number equal to the VLAN number.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the root path cost?

A

The cumulative outbound interface cost to get to the root bridge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How does a local switch calculate its root path cost?

A

It takes the root path cost advertised by its neighbor in a BPDU and then adds the interface cost of the local interface that BPDU was received on.

20
Q

How does a switch initially identify its Root Port (RP) along with 4 tie-breakers?

A
  • Port with lowest path cost to the Root
  • Port who’s neighbor has the lowest System Priority
  • Port whose neighbor has the lowest base MAC address
  • Port whose neighbor has the lowest port priority
  • Port whose neighbor has the lowest interface index number
21
Q

What can a Designated port NOT be and how is the DP initially determined along with 2 tie-breakers?

A
  • Cannot be a RP
  • Switch with lowest root path cost gets the DP
  • Switch with lowest System Priority wins
  • Switch with lowest MAC address wins
22
Q

What is the difference between a point-to-point port and a point-to-point edge port?

A

Point-to-point Edge has Portfast

23
Q

What happens with a switch receives a BPDU with the TCN bit flipped on?

A
  • All switches change their MAC address timer to the forward delay time (def 15 sec)
  • This causes all MAC entries that aren’t heard during that 15 seconds to be flushed.
24
Q

What is the difference between a Direct Link Failure and an Indirect Link Failure?

A
  • When a direct link failure occurs the links interfaces go down.
  • When an Indirect Link Failure occurs the interfaces are still up but data is impaired or corrupted.
25
Q

By default how long is a MAC address in the MAC table before it times out?

A

300 seconds

26
Q

What do non-root switches do when they receive a Configuration BPDU with the TCN flag set?

A

They change their MAC address timeout from the default 300 seconds to the Forward Delay time (15 seconds) to flush the MAC table.

27
Q

What are the 3 port states in RSTP?

A
  • Discarding
  • Learning
  • Forwarding
28
Q

In RSTP what is the Discarding State equivalent to in 802.1D STP?

A

Discarding combines the 802.1D port states of Disabled, Blocking, and Listening

29
Q

If a switch running RSTP detects a device connecting to it what does it do?

A
  • Attempts a RSTP handshake.
  • If the device does not respond the switch enables 802.1D on that port causing the port to go through Listening and Learning states.
30
Q

What are the 4 RSTP Port Roles?

A
  • Root Port (RP)
  • Designated Port (DP)
  • Alternate Port
  • Backup Port
31
Q

What does an Alternate Port do?

A

Is normally in blocking state but if the switch’s RP goes down then it provides alternate connectivity toward the Root Bridge via a different switch

32
Q

What does a Backup Port do and when would you see one?

A
  • Exists only when multiple links connect between same switches but a different port on the same switch was elected as the DP.
  • Normally in blocking state but if the DP goes down the backup port takes over as DP
33
Q

What are the 3 RSTP Port Types and how are they defined?

A
  • Edge Port - port running portfast
  • Root Port - port with lowest cost to the root
  • Point-to-point Port - port running full duplex
34
Q

What is the difference between 802.1D and CST

A
  • No difference. They are the same.
  • Both provide for only one STP instance. The opposite of PVST+.
35
Q

Which ‘show’ command identifies the Root Bridge?

A

show spanning-tree root

36
Q

What ‘show’ command will display the STP state (RP, DP, Blocking)

A

show spanning-tree vlan (vlan_id)

37
Q

Display spanning-tree detail about a specific port.

A

show spanning-tree int (interface_ID) detail

38
Q

Display information about TCNs.

A

show spanning-tree vlan (vlan_id) detail

39
Q

What are the short mode port costs for 10 Mbps, 100 Mbps, 1 Gbps, 10 Gbps, 20 Gbps, 100 Gbps, 1 Tbps, 10 Tbps?

A
  • 10 Mbps - 100
  • 100 Mbps - 19
  • 1 Gbps - 4
  • 10 Gbps - 2
  • 20 Gbps and higher - 1
40
Q

What are the long mode port costs for 10 Mbps, 100 Mbps, 1 Gbps, 10 Gbps, 20 Gbps, 100 Gbps, 1 Tbps, 10 Tbps?

A
  • 10 Mbps - 2,000,000
  • 100 Mbps - 200,000
  • 1 Gbps - 20,000
  • 10 Gbps - 2,000
  • 20 Gbps - 1,000 (half of 10 Gbps)
  • 100 Gbps - 200
  • 1 Tbps - 20
  • 10 Tbps - 2
41
Q

What are the 5 factors when choosing the root port?

A
  • Interface with the lowest root path cost
  • Interface with the neighbor that has the lowest system priority
  • Interface with the neighbor that has the lowest MAC address
  • Multiple links to same switch - neighbor’s interface with lowest port priority
  • Multiple links to same switch - neighbor’s interface that has lowest index
42
Q

How is the Designated Port chosen?

A
  • Must not be a root port
  • Switch with the lowest root path cost has the DP, if there is a tie then:
  • Switch with lowest system priority has the DP, if there is a tie then:
  • Switch with lowest MAC address has the DP
  • If multiple connections to same switch then neighbor interface with lowest priority has the DP
  • If multiple connections to same switch then neighbor interface with lowest interface index has the DP
43
Q

When choosing the RP or DP what are the 2 tie-breakers when there are multiple connections to the same switch?

A
  • choose the interface with the lowest port priority, if there’s a tie then
  • choose the interface with the lowest interface index
44
Q

What is the RSTP negotiation process?

A
  • sw1 sends bpdu with proposal bit set
  • sw2
    • moves all its non-edge ports to blocking
    • sends proposal bpdu’s to non-edge switches
    • replies to sw1 with bpdu with proposal bit cleared and agreement bit set
    • moves its port to sw1 to forwarding state
  • sw1 upon receiving agreement bpdu from sw2 moves its port to forwarding
45
Q

What are the 6 802.1D port states?

A
  • Disabled
  • Blocking
  • Listening
  • Learning
  • Forwarding
  • Broken

CCNP Core (46 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions