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ENCOR BOSON > Packet Switching > Flashcards

Packet Switching Flashcards

1
Q

What are the 7 layers of the OSI model? Please Do Not Throw Sausage Pizza Away

A

1) Physical - bits
2) Data Link (node to node transfer) - frames
3) Network (routing) - packets
4) Transport (UDP - datagrams /TCP - segments)
5) Session - data
6) Presentation - data
7) Application - data

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2
Q

What is a CAM table?

A

Content Addressable Memory - table is a data structure used by network switches to store information about MAC (Media Access Control) addresses and the physical switch ports associated with them (AKA MAC ADDRESS TABLE)

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3
Q

TCAM table

A

Ternary Content Addressable Memory (uses NVRAM) - allows for high-speed access to routing and access control information

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4
Q

What is a PDU

A

Protocol Data Unit - refers to the specific unit of data relevant to each layer in the OSI model. Each OSI layer has its own PDU type, encapsulating data with the necessary headers and/or trailers needed for that layer’s function before passing it to the next layer.

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5
Q

Displaying the CAM table aging time

A

SwitchA#show mac—address—table aging—time

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6
Q

Configuring the CAM table aging time

A

SwitchA (config) #mac—address—table aging—time 1200

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7
Q

Displaying all MAC addresses the switch has learned

A

SwitchA#show mac—address—table

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8
Q

Displaying MAC addresses learned through a specific switch port

A

SwitchA#show mac—address—table interface fastethernet 0/1

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9
Q

Displaying the CAM table entry for a specific MAC address

A

SwitchA#show mac—address—table address AF—D3—C0 43—FB—85

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10
Q

Which OSI model layer do “bits” belong to?

A

Layer1, Physical

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11
Q

Which OSI model layer do “frames” belong to?

A

Layer 2, Data Link

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12
Q

Which OSI model layer do “packets” belong to?

A

Layer 3, Network

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13
Q

Which OSI model layer do “segments (in TCP)” belong to?

A

Layer 4, Transport

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14
Q

Which OSI model layer do “datagrams (in TCP)” belong to?

A

Layer 4, Transport

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15
Q

Which OSI model layer do “session messages (or data) “ belong to?

A

Layer 5, Session

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16
Q

What is an ASIC

A

Application-Specific Integrated Circuits, specialized circuits for processing network data

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17
Q

Packet Switching: process switching

A

Slowest of the three packet switching methods, uses software and CPU of the switch, used for complex methods like NAT and encryption

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18
Q

Packet Switching: fast switching

A

“route caching” uses CPU only for first part

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19
Q

Packet Switching: CEF switching

A

Cisco Express Forwarding, AKA topology-based switching

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20
Q

To enable fast switching, issue… command at the global config mode

A

ip route-cache

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21
Q

To disable fast switching, issue… command at the global config mode

A

no ip route-cache

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22
Q

display the fast -switching cache

A

Router#show ip cache

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23
Q

display the RIB

A

Router#show ip route

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24
Q

display the FIB

A

Router#show ip cef

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25
Q

show the CEF adjacency table

A

Router#show adjacency

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26
Q

show the arp table

A

Router#show ip arp

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27
Q

configure CEF load balancing per packet

A

router(config-if)#ip load-sharing per-packet

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28
Q

configure CEF load balancing per packet

A

router(config-if)#ip load-sharing per-destination

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29
Q

configure the CEF load balancing algorythm

A

Router(config)#ip cef load-sharing algorythm xxxxxxxx

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30
Q

what are the 4 types of CEF LB algorythms?

A

origional
universal (default)
tunnel
include-ports (layer 4)

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31
Q

What are the QoS parameters for Layer 2 ?

A

802.1p CoS , 802.11 TID

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32
Q

QoS: what is COS?

A

Class of Service, Layer 2, 3-bit field in the VLAN (802.1Q),

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33
Q

QoS: what is ToS

A

Type of Service

34
Q

What are the QoS parameters for Layer 3 ?

A

IP ToS , DSCP

35
Q

QoS: DSCP

A

Differentiated Services CodePoint use 6 left most bits 2^6 or 64 possible classifications, Layer 3

36
Q

QoS: IP precedence

A

2^6 possible classifications

37
Q

QoS: PHB (DSCP)

A

Per Hop Bevaviors (21 labeled classifications out of 64) ITF created these. if the binary doesnt end in “0” it is not a class the ITF set up

38
Q

PHB - default (DSCP)

A

000000 or 0

39
Q

QoS: PHB - Expidited Forwarding (EF) (DSCP)

A

101110 or 46 (backwards compatible with IP precendence

40
Q

QoS: DCSP Assured Forwarding (AF) values

A

4 classes, but the first three binarys match the old IP precedence

41
Q

QoS: Random Early Detection, RED

A
42
Q

QoS - Explicit Congestion Notification (ECN)

A

The routers politly asking teh source to slow down bits 7 and 8 - 00 “rtr does not speak ECN”, a single one “rtr speaks ECN”, both bits are 1’s, rtr “speaks and is experiencing congestion”

43
Q

QoS: CB-WFQ

A

Class-Based Weighted Fair Queueing

44
Q

QoS What is Shaping

A

Polite, delays, queues (works with bits)

45
Q

QoS What is Policing

A

the Nazi that drops traffic (works with bytes)

46
Q

QoS: What is MQC

A

Modular Quality of Service, Command Line Interface

47
Q

QoS: What are Class Maps

A

Define and classify traffic types (Cisco recommends 11 or less classes)

48
Q

QoS: What are Policy Maps

A

Specify what QoS actions to apply to each class (e.g., bandwidth allocation, priority)

49
Q

QoS: What are Service Policies

A

Apply the policy map to an interface.

50
Q

Qos: what is the command to create a Class Map?

A

R1(config)#class-map match-any [CLASSNAME] –> match protocol [PROTOCOL]

51
Q

Qos: what is the command to show the class maps?

A

R1(config)#do show class-map

52
Q

Qos: what is the command to create a policy map?

A

policy-map[MAPNAME] –> class [CLASSNAME] –> [ACTION]

53
Q

QoS: what are the steps to setting up QoS/MQC?

A

setup classes, setup policies, apply to the interface

54
Q

QoS: what is the command to apply a policy to the interface?

A

R1(config-if)#service-policy output [POLICY NAME]

55
Q

QoS: powerful command to show a policy applied on an int

A

R1#show policy-map interface [INTERFACE NAME]

56
Q

QoS: What are the three versions of AutoQoS?

A

Router-based AutoQoS VoIP, Switch-based AutoQoS VoIP, & Router-based AutoQoS Enterprise

57
Q

QoS: Router-based AutoQoS VoIP only works on Ethernet ports

A

False: is only works on WAN circuits

58
Q

QoS: what is the command to implement router based auto QoS?

A

R1(config-if)# auto qos voip

59
Q

QoS: what is created using router based auto QoS?

A

Class maps referring to an extended ACL
An ACL that matches voice traffic,
A policy map

60
Q

QoS: command to start the autoQoS ENterprise process?

A

R1(config-if)#auto discover qos

61
Q

QoS: What are the steps of AutoQos Enterprise?

A

discovery (wait 2-3 days), look for what was discovered, apply what was discoered.

62
Q

QoS: how to view what auto QoS enterprise has discovered

A

R1#show auto discovery qos interface [INT NAME]

63
Q

QoS: how to apply what was discovered using auto qos enterprise

A

R1(config-if)# auto qos

64
Q

QoS: What are the 4 wifi access categories?

A

Voice (AC_VO)
Video (AC_VI)
Best Effort (AC_BE)
Background (AC_BK)

65
Q

WMM QoS IEEE 802.1P categories mapped to

A
66
Q

QOS: What is the the BE class?

A

Best Effort, low priority

67
Q

QOS: What is the the EF class?

A

Expedited Forwarding, highest class

68
Q

QOS: What is the the AF class?

A

Assurd Forwarding, AF Classes (1 to 4): Higher class numbers indicate higher priority within the AF class hierarchy.

69
Q

QoS: What are the 12 possible DSCP values for AF

A
70
Q

QoS: What are the category, CoS, and DSCP values in wireless QoS?

A
71
Q

QoS: what are the 4 basic queueing mecahnisms in congestion management?

A

FIFO (first in first out)
PQ (priority queueing)
CQ (custom queueing)
WFQ (Weighted Fair Queueing)

72
Q

QoS: FIFO (first in first out)

A

default, basically nothing

73
Q

QoS: PQ (priority queueing)

A

4 queues, guarantees high priority is first but can cause lower priority to be starved

74
Q

QoS: CQ (custom queueing)

A

16 queues,

75
Q

QoS: WFQ (weighted fair queueing)

A

256 queues, round robinsdistributes bandwidth based on class

76
Q

QoS: LFI (Link Fragmentation and Interleaving)

A

breaks up large packets so that small, jitter sensitive packets don’t have to wait so long)

77
Q

QoS: what are the 4 scheduling mechanisms?

A

Strict Priority
Round Robin
Weighted fair

78
Q

QoS: congestion avoidance, tail drop

A

drops off the last packets to open up more space in the queue

79
Q

QoS: congestion avoidence, RED (rendom early detection)

A

a congestion avoidance method that can avoid global synchronization

80
Q

QoS: congestion avaoidence, what is WRED

A

Ciscos version of RED, Weighted Random Early Detection, probability of a packet getting discarded is dependent on its IP precedence

81
Q

What are the three steps to setting up QoS?

A

Define the CLASS MAP
Define the POLICY MAP
LINK the Policy Map to the Interface

82
Q
A

ENCOR BOSON (3 decks)

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