2. Spanning Tree Protocol Flashcards

1
Q

What are the different types of SPT?

A
  • 802.1D
  • PVST
  • PVST+
  • 802.1W RSTP
  • MST
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2
Q

What are the 6 STP port states?

A
  • Disabled
  • Blocking (receive BPDU)
  • Listening (send/receive BPDU)
  • Learning (send/receive BPDU, adjust mactable)
  • Forwarding
  • Broken
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3
Q

What are the 3 STP port types?

A
  • Root port (1 per vlan)
  • Designated port (1 per link)
  • Blocking port
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4
Q

What are the 2 types of BPDU?

A
  • Configuration BPDU (discover the root bridge)

- Topology Change notification

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5
Q

How to change a switch to long mode?

A

spanning-tree pathcost method long

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6
Q

What are the long-mode costs?

A
  • 2.000.000
  • 200.000
  • 20.000
  • 2.000
  • 1000
  • 200
  • 20
  • 2
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7
Q

What does Spanning-Tree do?

A

Enables switches to become aware of other switches through the advertisement en receipt of BPDUs. It creates a L2 loop free topology

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8
Q

How can you recognize a root bridge?

A

All the ports are forwardering and designated

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9
Q

What are the root bridge election steps?

A
  • Every switch thinks it is the root bridge and sends out a config BPDU
  • If a received config BPDU has a higer bridge identifier it ignores
  • If a received config BPDU has a lower bridge identifier it updates its own BPDU

If priority is equal the lowest mac address counts

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10
Q

Why is a bridge priority always higher?

A

The vlan is added to the priority

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11
Q

What are the 5 steps for the roort port election?

A
  • Interface with the lowest path cost
  • Interface associated to the lowest system prio of advertising switch
  • Interface associated to the lowest mac of advertising switch
  • When multiple links are associated to the same switch, lowest port priority
  • When multiple links are associated to the same switch, lowest port number
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12
Q

What are the 2 port types on a catalyst switch?

A
  • P2P

- P2P edge

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13
Q

What happens when a switch discovers STP topology changes?

A

The switch that detects the change sends a Topology Change Notification BPDU towards the bridge. An upwards stream switch will ACK and forward the BPDU.

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14
Q

What happens when the root bridge receives a TCN BPDU?

A

It creates a new BPDU configuration wit hthe Topology Change flag set. and floods it.

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15
Q

What does a switch do when it receives a BPDU with the Topology Flag set?

A

They change their MAC timer to the forward delay timer (15 sec default). This flushes all macs of devices that did not respond within the 15 sec.
After a second BPDU the MAC timer is placed back to 300

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16
Q

What are the 3 RSTP port states?

A
  • Discarding
  • Learning (forwards BPDU, not other traffic)
  • Forwarding
17
Q

What are the 4 RSTP port roles?

A
  • Root port
  • Disgnated port
  • Alternate port
  • Shared segment
18
Q

What are the 3 802.1W port types?

A
  • Edge port
  • Non edge port
  • P2P