365 - Advanced networking

OpenFlow, forwarding, SDN

A network communications protocol that allows controllers to configure switches and manage -- tables in a -- architecture.

SDN Controller, devices, OpenFlow

Manages and controls the flow of traffic across the network by communicating with network -- through --

Switch

A hardware device in a network that connects devices and forwards data between them

Router

A network device that directs traffic between different networks

Forwarding tables

Lookup tables in switches or routers that contain rules for handling network packets

Software Defined Networking, data, control

An approach to building networks involving separating the -- plane and the -- plane that are traditionally combined.

Data plane, packet, header

Applies forwarding of network devices and focuses on -- processing and -- lookup.

Control plane

Decides forwarding in network devices.

Flow Table, statistics, switching, firewalls

Located in the OpenFlow Switch, it contains rules, actions, and --. Can be used for flow --, -- and routing

Centralised control

a single controller can manage multiple switches

Distributed control

multiple controllers can manage different parts of the network

Reactive

flows are created on-demand, if a packet with no matching rule arrives, the controller creates a new flow for it

Proactive

controller pre-populates the flow table in the switch

Flow-based

every flow is individually set up by the controller using exact-match flow entries

Aggregated

one flow entry covers large groups of flows using wildcard flow entries

Southbound API

enables communication between the control and data planes (like OpenFlow)

Northbound API

enables applications to interface with the network

Network Functions Virtualization, hypervisor, load balancing

The replacement of network appliance hardware with virtual machines. The VMs use a -- to run networking software and processes like routing and -- --

Hypervisor, virtual, resources

software or hardware that allows multiple -- machines to run on a single physical computer. Manages and allocates -- to each VM

Virtual Network Function, commodity, dynamic

A software implementation of a network function that can run on -- hardware. NFV enables the -- creation of a chain of service elements composed of VNFs.

Application-Specific Integrated Circuit

An integrated circuit chip (IC) customised for a particular use rather than for general purpose.

Ethernet forwarding, MAC

The process by which ethernet switches direct network traffic based on the — address of each frame

Routing, subnets

The process of selecting a path for traffic to travel through a network. It delivers packets across network — using IPv4 and IPv6 addresses

Middleboxes, inspects, manipulates, standardisation

A computer networking device that transforms, i-, filters and m- traffic for purposes other than packet forwarding.They manipulate packet fields across layers and have limited --.

ToR Switch, datacenter

network switches that connect devices in a server rack to a network. They are deployed on — and enterprise edges

Hash, Cuckoo, TCAM, Radix

Lookup mechanisms; -- table, -- hashing, --, -- tree

Hash table, memory

a data structure used to look-up key-value pairs, fixed width lookup using a hash function to convert fields into a -- index

Cuckoo hashing, collisions, 1

a closed-form hashing where -- are eliminated using two hash functions and two tables, guaranteed O(--) lookup complexity

Ternary Content Addressable Memory, clock cycle , parallelisation

a specialised type of high-speed memory that searches its entire contents in a single -- --, fixed-width and size mechanism with hardware -- for fast lookups

Radix Tree, trie

a data structure that represents a prefix tree (--) where each node that is only a child is merged with its parent, fixed-width lookup, trade memory size for lookup time

Packet arbitration, collisions

a mechanism that ensures that only one device transmits packets at a time, prevent -- and ensuring data transfer

Leaky bucket, token bucket

Packet arbitration types (2)

Leaky bucket

A packet arbitration technique where packets are transmitted at a fixed rate, if the bucket is full, incoming packets are dropped or queued

Token bucket

A packet arbitration technique where tokens (represents permission to send data) are added to a bucket at a fixed rate, when a packet needs to be sent, it can only be transmitted if there is a token available (which is then removed)

Queuing delay, link utilization, fairness, packet drops

Queue management goals 1. Control average -- -- and maintain high -- --. 2. Improving -- and reducing unnecessary -- --.

Output, Input, CIOQ

Packet queuing types -- queued routers, -- queued routers, -- routers (Store packets only at output or input or both interfaces)

IEEE 802.3 Ethernet

a set of standards for ethernet defining the physical and data link layers of wired Ethernet networks

Radio signals, sinusoidal, frequency, phase

Data is transmitted by modulating -- signals, parameters including amplitude, -- and --

Signal strength, interference, multipath, medium sensing

Wireless characteristics; Decreased -- --, -- from other sources, -- propagation, -- -- limitations

Multipath Propagation

Where signals reflect off objects and arrive at different times

Medium sensing limitations

Radio technologies cannot detect collisions during transmissions

Additive noise, overlays

A constant background noise that -- the signal

Multiplicative noise, scales

Noise that -- with the amplitude of the signal

Signal to Noise Ratio

A measure of the clarity and quality of a signal in the presence of noise.

Desired signal, background noise

SNR Compares the level of -- -- to the level of -- --

Multiplexing, pre-allocation, contention, CSMA/CD

Medium sharing techniques; --, -- access schemes, -- protocols, --/-

Multiplexing

Combines multiple signals into a single carrier

Pre allocation access schemes

Allocate a dedicated resource for each node, which are otherwise wasted if not in use

Contention protocols

Use a distributed mechanism to coordinate medium access

CSMA/CD

Checks if medium is free before transmitting

IEEE 802.11

A set of standards for WLANs (Wireless Area Networks), they define how devices communicate over WiFi

Frequency Division Multiplexing, resources

Transmits signals on different frequencies (wastes --)

Time Division Multiplexing, latency, synchronisation

Transmitted signals on fixed intervals (has increased -- and -- issues)

Code Division Multiple Access, minimal interference

Assigns a unique code to each user, codes are independent and users can transmit simultaneously with -- --

Space division multiplexing, MIMO

Uses space to isolate signals including techniques like --

Multiple Input Multiple Output, transmission rates, reliability

A wireless communication technology that uses multiple antenna at both the transmitter and receiver (improve data -- -- and --)

Long-Term Evolution

A standard for wireless cellular broadband technology. It features a separation of the data plane and control plane.

Transport layer

Facilitates logical communication between processes on network hosts, the sender divides messages into segments and the receiver reassembles these segments.

Packet multiplexing

the process of combining multiple data streams into a single stream (packets)

TCP Flags

A specific control bit used to indicate the particular state or control function within TCP connection.

Stop, wait, Go back , Cumulative, Selective

Retransmission policies - -- and --, -- -- N, -- ACK, -- ACK

Stop and wait, single packet

Maintains a sender window of a -- -- (Wait for ACK before sending next packet)

Go back N, one, retransmitted

Maintains a sender window greater than --, if a packet is lost the whole window is --.

Cumulative ACK

Stores successfully received packets, ACK numbers are cumulative

Selective ACK, missing segments

Allows acknowledgement of individual segments, receiver can request the retransmission of only -- --

Fast retransmit

A mechanism used to reduce the time spent waiting for lost packets to be detected

Congestion

Occurs when the input rate is greater than the output rate over long periods

Window based congestion control, congestion, conditions

A method used to manage the rate at which data packets are sent over a network, involves adjusting the size of the -- window based on network --

Slow start, exponentially, threshold

Congestion window starts small and grows -- with each ACK received until it reaches the slow start --

Retransmission timeout

the time TCP waits for an ACK before retransmitting

Pulse Code Modulation

Encoding technique of converting analog audio to digital audio.

Regular intervals, discrete, binary code

PCM process - analog signal is measured at -- --, each sample is rounded to the nearest value within a range of -- levels, these values are converted into -- --.

Image compression

A method used to reduce the number of bits needed to represent an image without negatively affecting the quality of the image

Spatial coding, redundancies

Image coding used to reduce the data required to represent an image by analysing and encoding the spatial -- within the image

Temporal coding, differences

Image coding that reduces the data required to represent a video by only sending the -- between frames rather than the entire frame

Constant Bit Rate

the video encoding rate is fixed

Variable Bit Rate

the video encoding rate changes as the amount of spatial and temporal coding changes

Video encoding rate

the amount of bits of information that is stored per second of video

Stored, conversational, streaming

Multimedia networking application types; Streaming -- audio/video, -- voice/video over IP, -- live audio/video

Continuous playout constraint, timing, jitter, buffer, stuttering

Once client playout begins, playback must match the original --, since network delays are variable (--) a client side -- is used to match playout requirements. Prevents interruptions or -- during streaming

Initial playout delay tradeoff

Happens when the system waits longer before starting playback so the buffer has more time to fill up

Real time Transport Protocol, multimedia payload

a network protocol for delivering audio and video over IP networks, it is used in communication and entertainment systems involving streaming media and defines -- -- types.

Media control server, ongoing session

Streaming multimedia via UDP requires a -- -- -- for processing client-server interactivity requests for each -- --

Streaming multimedia HTTP

The multimedia file is retrieved via HTTP GET using TCP

Dimensioning, link capacity

a method used to ensure reliable multimedia traffic transmission without delays or losses, involves deploying enough -- -- so congestion doesn’t occur

Link capacity

the maximum amount of data that can be transmitted over a network link

Packet scheduling

the process of selecting the next packet to be processed

First come first serve, multiclass priority, round robin, weighted fair

Packet scheduling methods; -- -- -- --, simply -- --, -- --, -- -- queueing

Packet policing

the process of regulating the flow of data packets

Token bucket, Weighted Fair Queue

Packet policing methods

Diffserv, qualitative service classes

A class of service model to specify and control IP network traffic by class. Provides -- -- -- so different types of traffic are treated differently.

Edge router

Represent the border crossing between internal and external networks

Diffserv Edge router, per flow

Responsible for — traffic management and marking packets as in profile (conforming to a traffic profile) or out of profile

Diffserv Core Router, per class

Performs — — traffic management, buffering and scheduling decisions are based on packet marking done at the edge router

Per-connection QoS guarantees, reserving resources

A network providing a guaranteed level of service for individual traffic flows or connections, requires -- -- in the network

Call admission control

used to prevent the over-subscription of network resources for Per-connection QoS guarantees

Domain Name Service, hierarchy, application

a distributed database implemented in a -- of many name servers, functions on the -- layer and allows hosts and name servers to resolve names (translate from numerical IPs to domain names)

Mega servers, failure, congestion, geographical

A solution attempt for multimedia distribution, involves distributing load at a central server site using server farms. Single point of --, network --, -- distance issue

Web caches, load, response, frequently changing

A solution attempt for multimedia distribution, users configure their browsers to point to a local web cache, cache either directly returns objects or requests it from the origin server. Reduced -- and improved -- times but not suitable for -- -- content

Content Distribution Networks, network load

A geographically distributed group of servers that caches content close to end users, allowing for the quick transfer of assets needed for loading internet content. Reduces -- -- but is expensive