Brainscape's Knowledge GenomeTM

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


See full index

INFO5082 - Multilayer Switching > Review - Chapter 4 > Flashcards

Review - Chapter 4 Flashcards

1
Q

STP

A
  • Layer 2 protocol

* Provides network link redundancy while eliminating potential problems

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

STP Limitation

A

Convergence delay after a topology change

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

BPDUs (STP)

A

○ Used to determine current topology information and how to react if any devices are added/removed/changed in the topology
○ Sent every 2 seconds by default on all switch ports

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

STP Rules

A

○ One root bridge
○ One root port on each non-root switch
○ One designated port per LAN segment
○ Non designated ports are blocked

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

STP Timers

A

○ Hello time (2s)
○ Forward delay (15s)
○ Max age (20s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Key Types of STP

A 
○ STP (original IEEE 802.1D version)
○ Common Spanning Tree (CST)
○ PVST and PVST+ (Cisco proprietary)
○ Multiple Spanning Tree (MST)
○ Rapid Spanning Tree (RSTP)
○ RPVST+ (Cisco implementation of RSTP based on PVST+)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Root Bridge

A

Selected based on lowest Bridge ID (BID)

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

Bridge ID (BID)

A

Two parts:
○ Priority
○ Mac address

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

Root Port Factors

A

○ Path Cost
○ Lowest Sender BID
○ Lowest Port ID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Bridge Protocol Data Units (BPDUs)

A
  • Used to exchange STP information, specifically for root bridge election and loop identification
  • Sent every 2 seconds by default
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Types of BPDUs

A

○ Configuration BPDUs

○ TCN (topology change notification) BPDUs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

STP Port States

A 
○ Blocking
○ Listening (15s)
○ Learning (15s)
○ Forwarding
○ Disabled
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Per VLAN STP+ (PVST+)

A

• Runs one spanning-tree instance for each VLAN
• The original 16-bit bridge priority is split into two fields, resulting in the following components in the BID:
○ Bridge priority
○ Extended system ID
○ MAC address

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

Bridge priority

A

○ 4-bit field carrying bridge priority
○ Default is 32,768 (midrange)
○ Conveyed in discrete values in increments of 4096

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

Extended system ID

A

12-bit field carrying VLAN ID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

MAC address

A

6-byte field with MAC address of the switch

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

Types of Topology Changes

A
  • Direct topology change
  • Indirect topology change
  • Insignificant topology change
18
Q

Direct Topology Change

A

Can be detected on an interface

19
Q

Indirect topology change

A

Detected because no BPDUs are received from the root bridge

20
Q

Insignificant topology change

A

Occurs if an event causes a switch to send out TCNs (no actual topology change occurs)

21
Q

Rapid Spanning Tree Protocol (RSTP)

A
  • 802.1W

* Speeds up the recalculations after topology change

22
Q

RSTP Port Roles

A
  • Root
  • Designated
  • Alternate
  • Disabled
  • Backup
23
Q

RSTP Port States

A
  • Discarding
  • Learning
  • Forwarding
24
Q

RSTP Rapid Transition

A

Rapid transitions to forward state on:
• Edge ports
• Point-to-point links

25
Q

RSTP Timers

A

Designated ports wait 2x forwarding delay before forwarding

26
Q

UplinkFast

A

Fast uplink failover on access switch

27
Q

BackboneFast

A

Fast convergence in distribution/core layer when STP change occurs

28
Q

PortFast

A

Configures access port to transition directly to forwarding state

29
Q

BPDU Guard

A

Disables PortFast-enabled port if a BPDU is received

30
Q

BPDU Filter

A

Suppresses BPDUs on ports

31
Q

Root Guard

A

Prevents external switches from becoming roots

32
Q

Loop Guard

A

Prevents an alternate port from becoming the designated port if no BPDUs are received

33
Q

Unidirectional Link Detection (UDLD)

A

Detects when a unidirectional link exists and shuts down the affected interface

34
Q

UDLD Packets

A

Sent to an STP neighbor every 15s

35
Q

Flex Links

A

Layer 2 availability feature which provides link redundancy with a convergence time of less than 50ms

36
Q

Multiple Spanning Tree Protocol (MST)

A

• Main purpose is to reduce the total number of spanning-tree instances to match the physical topology of the network (Reduces the CPU cycles of a switch)

37
Q

MST Configuration Attributes

A

○ An alphanumeric name (32 bytes)
○ A configuration revision number (2 bytes)
○ A 4096-element table that associates each VLAN to an instance

38
Q

Extend System ID

A

12-bit field used in MST and carries the MST instance number

39
Q

MST Regions

A

A group of switches must share the same configuration attributes to be part of a common MST region

40
Q

STP Instances with MST

A

MST supports a number of instances but doesn’t send BPDUs for every active STP instance separately

41
Q

Instance 0 (STP with MST)

A

The internal spanning tree (IST)
○ Designed to carry all STP-related information
○ MSTI information is carried in the IST’s BPDU in so-called M-Record fields (one for every active MSTI)

42
Q

Potential STP Problems

A
  • Duplex mismatch
  • Unidirectional link failure
  • Frame corruption
  • Resource errors
  • PortFast configuration error

INFO5082 - Multilayer Switching (7 decks)

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