softwareisation and virtualisation

Question 1

network programmability

Answer 1

being able to control network devices and their behaviour using API to modify and configure network devices dynamically

Question 2

what are 3 benefits of network programmability

Answer 2

reduces human intervention
ensure consistency
enable faster response to charging traffic patterns and business needs

Question 3

what are the two key roles in network programmability

Answer 3

automation; trigger network changes dynamically
api usage; provide the interface between applications and network devices for configuration and monitoring

Question 4

software defined network sdn

Answer 4

allows centralised control of the network making dynamic network management and configuration easier

Question 5

generalised flow based routing

Answer 5

simple packet handling rules that considers all the headers of all layers

Question 6

what is the role of the remote controller in sdn

Answer 6

computes and installs forwarding tables in the router

Question 7

how does the controller create and install the forwarding tables

Answer 7

the routers share information with the controller which then uses its software to create routing/flow tables for all the routers therefore the dont have to exchange any information directly with each other

Question 8

what are 4 benefits of sdn

Answer 8

centralised network management by the controller
cost effective and scalable
easy dynamic traffic engineering
enables automation

Question 9

how is sdn cost effective and scalable

Answer 9

reduces the need for specialised hardware

Question 10

how does sdn enable automation

Answer 10

reduces human error and operational overhead
automated failure detection and adaptive traffic engineering

Question 11

how was traffic engineering difficult with traditional routing

Answer 11

can only use the link weights as control
need a new routing algorithm when splitting incoming traffic

Question 12

what are data plane switches

Answer 12

fast simple switches implementing generalised data plane forwarding in hardware

Question 13

how do data plane switches work

Answer 13

follow pre installed forwarding rules provided by the controller via the flow table
the api for the switch control defines what is controllable and what isnt and provides a way for the controller to manage flow tables in switched

Question 14

what is the role of the sdn controller

Answer 14

maintains the network state info

Question 15

how is the sdn controller implemented

Answer 15

as a distributed system which allows for fault tolerance performance robustness and scalability

Question 16

how does the sdn controller interact with the network control applications ‘above’

Answer 16

via the northbound api

Question 17

how does the sdn controller interact with the network switches ‘below’

Answer 17

via the southbound api

Question 18

what are the 3 components of the sdn controller

Answer 18

interface layer
network wide state management
communication

Question 19

interface layer component in the sdn controller

Answer 19

controller provides an api for network control apps to interact with simplifying the complex network operations so control apps can manage the network without dealing with low level details

Question 20

network wide state management component in the sdn controller

Answer 20

all network info is stored in a distributed database to keep track of the network state

Question 21

communication component in the sdn controller

Answer 21

between the controller and the controlled switches using a protocol allowing the controller to manage the network and update the switch controller in real time

Question 22

network control applications

Answer 22

the brains of control
implement control functions using lower level services

Question 23

how are network control apps unbounded and how is this a benefit

Answer 23

can be provided by a third party allowing freedom for managers and administrators

Question 24

match in generalised forwarding

Answer 24

pattern values in packet header files

Question 25

actions in generalised forwarding

Answer 25

for matched packet you can drop, forward and modify or send to the controller

Question 26

priority in generalised forwarding

Answer 26

disambiguate overlapping patterns

Question 27

flow

Answer 27

defined by header values

Question 28

what defines the match and action rules

Answer 28

the router flow table

Question 29

open flow

Answer 29

a match and action based generalised forwarding protocol

Question 30

how does open flow protocol work

Answer 30

used a table based approach where the match fields specify which actions to take

Question 31

* in open flow

Answer 31

wildcard this field should not be considered when determining whether a packet matches a rule

Question 32

what is the point of match and action abstraction

Answer 32

unifies the flow of different kinds of devices

Question 33

why do we use tcp for open flow

Answer 33

need to encrypt as the information carried could be used for malicious attacks

Question 34

what is the match and action for a router

Answer 34

match; longest destination ip prefix action; forward the packet out of the appropriate interface

Question 35

what is the match and action for a firewall

Answer 35

match; filtering cia the ip and tcp/udp port number action; permit/deny

Question 36

what is the match and action for a switch

Answer 36

match; destination mac address action; forward the packet to a specific port or flood it

Question 37

what is the match and action for NAT

Answer 37

match; identify using the ip and port number action; rewrite the port and ip

Question 38

what does network function virtualisation(nfv) do

Answer 38

decouples network functions from proprietary hardware allowing them to run as software on generic hardware

Question 39

what are 4 benefits of nfv

Answer 39

cost efficiency easy to scale up or down flexible as you can get new features quicker energy efficient

Question 40

how is network function virtualisation(nfv) cost efficient

Answer 40

reduces the need for expensive hardware and will only need to purchase new software

Question 41

how is network function virtualisation(nfv) energy efficient

Answer 41

reduces hardware footprint and energy consumption

Question 42

what are the 3 types of architecture needed in nfv

Answer 42

virtual network functions (vnf) nfv infrastructure management and orchestration of the vnf and their interfaces

Question 43

virtual network functions in network function virtualisation(nfv)

Answer 43

software based implementations of traditional network functions

Question 44

nfv infrastructure

Answer 44

hardware and software that supports the vnf

Question 45

what is network slicing

Answer 45

the network is divided into virtual slices to deliver tailored services

Question 46

how are networks sliced

Answer 46

can create virtual networks that exist on top of a shared physical infrastructure and each one can be optimised for different needs

Question 47

how are physical networks sliced

Answer 47

partitioned into logical slices to provide tailored services without the need for separate physical infrastructure

Question 48

what is a reason to create e network slice on demand

Answer 48

to meet the specific needs of a user or service orchestrated on the controller