The document discusses integrated and differentiated services for managing internet traffic. Integrated services (ISA) allow traffic to reserve resources and receive guaranteed quality of service. Differentiated services classify traffic into groups that receive different treatment. Interior routers implement per-hop behaviors like expedited forwarding to give preferential treatment based on packet codes. Boundary routers condition traffic to enforce service level agreements.
The network layer is responsible for routing packets from the source to destination. The routing algorithm is the piece of software that decides where a packet goes next (e.g., which output line, or which node on a broadcast channel).For connectionless networks, the routing decision is made for each datagram. For connection-oriented networks, the decision is made once, at circuit setup time.
Routing Issues
The routing algorithm must deal with the following issues:
Correctness and simplicity: networks are never taken down; individual parts (e.g., links, routers) may fail, but the whole network should not.
Stability: if a link or router fails, how much time elapses before the remaining routers recognize the topology change? (Some never do..)
Fairness and optimality: an inherently intractable problem. Definition of optimality usually doesn't consider fairness. Do we want to maximize channel usage? Minimize average delay?
When we look at routing in detail, we'll consider both adaptive--those that take current traffic and topology into consideration--and nonadaptive algorithms.
Carrier-sense multiple access with collision detection (CSMA/CD) is a media access control method used most notably in early Ethernet technology for local area networking.Carrier-sense multiple access with collision detection is a media access control method used most notably in early Ethernet technology for local area networking. It uses carrier-sensing to defer transmissions until no other stations are transmitting.
description of the services to the networks .
how to apply quality of service
how to improve the networks
summary in personal point of view
please don't hesitate if you have further question
In multicast communication, there is one source and a group of destination.
In multicasting, the router may forward the received packet through several of its interfaces.
The source address is a unicast address, but destination address is a group address.
The network layer is responsible for routing packets from the source to destination. The routing algorithm is the piece of software that decides where a packet goes next (e.g., which output line, or which node on a broadcast channel).For connectionless networks, the routing decision is made for each datagram. For connection-oriented networks, the decision is made once, at circuit setup time.
Routing Issues
The routing algorithm must deal with the following issues:
Correctness and simplicity: networks are never taken down; individual parts (e.g., links, routers) may fail, but the whole network should not.
Stability: if a link or router fails, how much time elapses before the remaining routers recognize the topology change? (Some never do..)
Fairness and optimality: an inherently intractable problem. Definition of optimality usually doesn't consider fairness. Do we want to maximize channel usage? Minimize average delay?
When we look at routing in detail, we'll consider both adaptive--those that take current traffic and topology into consideration--and nonadaptive algorithms.
Carrier-sense multiple access with collision detection (CSMA/CD) is a media access control method used most notably in early Ethernet technology for local area networking.Carrier-sense multiple access with collision detection is a media access control method used most notably in early Ethernet technology for local area networking. It uses carrier-sensing to defer transmissions until no other stations are transmitting.
description of the services to the networks .
how to apply quality of service
how to improve the networks
summary in personal point of view
please don't hesitate if you have further question
In multicast communication, there is one source and a group of destination.
In multicasting, the router may forward the received packet through several of its interfaces.
The source address is a unicast address, but destination address is a group address.
Communication over the kinds of Data-Links used for unmanned vehicles presents important challenges dues to the low bandwidth, intermittent, and lower reliability of these links. Classic network protocols such as TCP do not operate well in this environment forcing application developers to implement their own reliability and session management. This presentation describes he issues and alternatives.
Online aptitude test management system project report.pdfKamal Acharya
The purpose of on-line aptitude test system is to take online test in an efficient manner and no time wasting for checking the paper. The main objective of on-line aptitude test system is to efficiently evaluate the candidate thoroughly through a fully automated system that not only saves lot of time but also gives fast results. For students they give papers according to their convenience and time and there is no need of using extra thing like paper, pen etc. This can be used in educational institutions as well as in corporate world. Can be used anywhere any time as it is a web based application (user Location doesn’t matter). No restriction that examiner has to be present when the candidate takes the test.
Every time when lecturers/professors need to conduct examinations they have to sit down think about the questions and then create a whole new set of questions for each and every exam. In some cases the professor may want to give an open book online exam that is the student can take the exam any time anywhere, but the student might have to answer the questions in a limited time period. The professor may want to change the sequence of questions for every student. The problem that a student has is whenever a date for the exam is declared the student has to take it and there is no way he can take it at some other time. This project will create an interface for the examiner to create and store questions in a repository. It will also create an interface for the student to take examinations at his convenience and the questions and/or exams may be timed. Thereby creating an application which can be used by examiners and examinee’s simultaneously.
Examination System is very useful for Teachers/Professors. As in the teaching profession, you are responsible for writing question papers. In the conventional method, you write the question paper on paper, keep question papers separate from answers and all this information you have to keep in a locker to avoid unauthorized access. Using the Examination System you can create a question paper and everything will be written to a single exam file in encrypted format. You can set the General and Administrator password to avoid unauthorized access to your question paper. Every time you start the examination, the program shuffles all the questions and selects them randomly from the database, which reduces the chances of memorizing the questions.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
HEAP SORT ILLUSTRATED WITH HEAPIFY, BUILD HEAP FOR DYNAMIC ARRAYS.
Heap sort is a comparison-based sorting technique based on Binary Heap data structure. It is similar to the selection sort where we first find the minimum element and place the minimum element at the beginning. Repeat the same process for the remaining elements.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
1. Chapter 17 Integrated and Differentiated Services
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ChapterChapter 1717
Integrated and Differentiated
Services
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IntroductionIntroduction
New additions to Internet increasing traffic
– High volume client/server application
– Web
Graphics
– Real time voice and video
Need to manage traffic and control congestion
IEFT standards
– Integrated services
Collective service to set of traffic demands in domain
– Limit demand & reserve resources
– Differentiated services
Classify traffic in groups
Different group traffic handled differently
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Integrated ServicesIntegrated Services
Architecture (ISA)Architecture (ISA)
IPv4 header fields for precedence and type
of service usually ignored
ATM only network designed to support
TCP, UDP and real-time traffic
– May need new installation
Need to support Quality of Service (QoS)
within TCP/IP
– Add functionality to routers
– Means of requesting QoS
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Internet Traffic – ElasticInternet Traffic – Elastic Can adjust to changes in delay and throughput
E.g. common TCP and UDP application
– E-Mail – insensitive to delay changes
– FTP – User expect delay proportional to file size
Sensitive to changes in throughput
– SNMP – delay not a problem, except when caused by
congestion
– Web (HTTP), TELNET – sensitive to delay
Not per packet delay – total elapsed time
– E.g. web page loading time
– For small items, delay across internet dominates
– For large items it is throughput over connection
Need some QoS control to match to demand
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Internet Traffic – InelasticInternet Traffic – Inelastic
Does not easily adapt to changes in delay and
throughput
– Real time traffic
Throughput
– Minimum may be required
Delay
– E.g. stock trading
Jitter - Delay variation
– More jitter requires a bigger buffer
– E.g. teleconferencing requires reasonable upper bound
Packet loss
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Inelastic Traffic ProblemsInelastic Traffic Problems
Difficult to meet requirements on network with
variable queuing delays and congestion
Need preferential treatment
Applications need to state requirements
– Ahead of time (preferably) or on the fly
– Using fields in IP header
– Resource reservation protocol
Must still support elastic traffic
– Deny service requests that leave too few resources to
handle elastic traffic demands
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ISA ApproachISA Approach
Provision of QoS over IP
Sharing available capacity when congested
Router mechanisms
– Routing Algorithms
Select to minimize delay
– Packet discard
Causes TCP sender to back off and reduce load
Enahnced by ISA
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FlowFlow
IP packet can be associated with a flow
– Distinguishable stream of related IP packets
– From single user activity
– Requiring same QoS
– E.g. one transport connection or one video stream
– Unidirectional
– Can be more than one recipient
Multicast
– Membership of flow identified by source and destination IP
address, port numbers, protocol type
– IPv6 header flow identifier can be used but isnot necessarily
equivalent to ISA flow
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ISA FunctionsISA Functions
Admission control
– For QoS, reservation required for new flow
– RSVP used
Routing algorithm
– Base decision on QoS parameters
Queuing discipline
– Take account of different flow requirements
Discard policy
– Manage congestion
– Meet QoS
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ISA Implementation in RouterISA Implementation in Router
Background
Functions
Forwarding
functions
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ISA Components – BackgroundISA Components – Background
FunctionsFunctions
Reservation Protocol
– RSVP
Admission control
Management agent
– Can use agent to modify traffic control
database and direct admission control
Routing protocol
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ISA Components – ForwardingISA Components – Forwarding
Classifier and route selection
– Incoming packets mapped to classes
Single flow or set of flows with same QoS
– E.g. all video flows
Based on IP header fields
– Determines next hop
Packet scheduler
– Manages one or more queues for each output
– Order queued packets sent
Based on class, traffic control database, current and past
activity on outgoing port
– Policing
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ISA ServicesISA Services
Traffic specification (TSpec) defined as
service for flow
On two levels
– General categories of service
Guaranteed
Controlled load
Best effort (default)
– Particular flow within category
TSpec is part of contract
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Token BucketToken Bucket
Many traffic sources can be defined by
token bucket scheme
Provides concise description of load
imposed by flow
– Easy to determine resource requirements
Provides input parameters to policing
function
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ISA Services –ISA Services –
Guaranteed ServiceGuaranteed Service
Assured capacity level or data rate
Specific upper bound on queuing delay through
network
– Must be added to propagation delay or latency to get
total delay
– Set high to accommodate rare long queue delays
No queuing losses
– I.e. no buffer overflow
E.g. Real time play back of incoming signal can
use delay buffer for incoming signal but will not
tolerate packet loss
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ISA Services –ISA Services –
Controlled LoadControlled Load
Tightly approximates to best efforts under unloaded
conditions
No upper bound on queuing delay
– High percentage of packets do not experience delay over
minimum transit delay
Propagation plus router processing with no queuing delay
Very high percentage delivered
– Almost no queuing loss
Adaptive real time applications
– Receiver measures jitter and sets playback point
– Video can drop a frame or delay output slightly
– Voice can adjust silence periods
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Queuing DisciplineQueuing Discipline
Traditionally first in first out (FIFO) or first
come first served (FCFS) at each router port
No special treatment to high priority packets
(flows)
Small packets held up by large packets ahead of
them in queue
– Larger average delay for smaller packets
– Flows of larger packets get better service
Greedy TCP connection can crowd out altruistic
connections
– If one connection does not back off, others may back
off more
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Fair Queuing (FQ)Fair Queuing (FQ)
Multiple queues for each port
– One for each source or flow
– Queues services round robin
– Each busy queue (flow) gets exactly one packet per
cycle
– Load balancing among flows
– No advantage to being greedy
Your queue gets longer, increasing your delay
– Short packets penalized as each queue sends one
packet per cycle
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Processor SharingProcessor Sharing
Multiple queues as in FQ
Send one bit from each queue per round
– Longer packets no longer get an advantage
Can work out virtual (number of cycles)
start and finish time for a given packet
However, we wish to send packets, not bits
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Bit-Round Fair QueuingBit-Round Fair Queuing
(BRFQ)(BRFQ)
Compute virtual start and finish time as
before
When a packet finished, the next packet
sent is the one with the earliest virtual
finish time
Good approximation to performance of PS
– Throughput and delay converge as time
increases
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ExamplesExamples
of PS andof PS and
BRFQBRFQ
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ComparisonComparison
of FIFO, FQof FIFO, FQ
and BRFQand BRFQ
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Generalized Processor SharingGeneralized Processor Sharing
(GPS)(GPS)
BRFQ can not provide different capacities to
different flows
Enhancement called Weighted fair queue (WFQ)
From PS, allocate weighting to each flow that
determines how many bots are sent during each
round
– If weighted 5, then 5 bits are sent per round
Gives means of responding to different service
requests
Guarantees that delays do not exceed bounds
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Weighted Fair QueueWeighted Fair Queue
Emulates bit by bit GPS
Same strategy as BRFQ
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Proactive Packet DiscardProactive Packet Discard
Congestion management by proactive
packet discard
– Before buffer full
– Used on single FIFO queue or multiple queues
for elastic traffic
– E.g. Random Early Detection (RED)
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Random Early Detection (RED)Random Early Detection (RED)
MotivationMotivation
Surges fill buffers and cause discards
On TCP this is a signal to enter slow start phase,
reducing load
– Lost packets need to be resent
Adds to load and delay
– Global synchronization
Traffic burst fills queues so packets lost
Many TCP connections enter slow start
Traffic drops so network under utilized
Connections leave slow start at same time causing burst
Bigger buffers do not help
Try to anticipate onset of congestion and tell one
connection to slow down
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RED Design GoalsRED Design Goals
Congestion avoidance
Global synchronization avoidance
– Current systems inform connections to back
off implicitly by dropping packets
Avoidance of bias to bursty traffic
– Discard arriving packets will do this
Bound on average queue length
– Hence control on average delay
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RED Algorithm – OverviewRED Algorithm – Overview
Calculate average queue size avg
if avg < THmin
queue packet
else if THmin ≤ avg < Thmax
calculate probability Pa
with probability Pa
discard packet
else with probability 1-Pa
queue packet
else if avg ≥ THmax
discard packet
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RED Algorithm DetailRED Algorithm Detail
34. Chapter 17 Integrated and Differentiated Services
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Differentiated Services (DS)Differentiated Services (DS)
ISA and RSVP complex to deploy
May not scale well for large volumes of traffic
– Amount of control signals
– Maintenance of state information at routers
DS architecture designed to provide simple, easy
to implement, low overhead tool
– Support range of network services
Differentiated on basis of performance
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Characteristics of DSCharacteristics of DS
Use IPv4 header Type of Service or IPv6 Traffic Class
field
– No change to IP
Service level agreement (SLA) established between
provider (internet domain) and customer prior to use of
DS
– DS mechanisms not needed in applications
Build in aggregation
– All traffic with same DS field treated same
E.g. multiple voice connections
– DS implemented in individual routers by queuing and
forwarding based on DS field
State information on flows not saved by routers
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ServicesServices
Provided within DS domain
– Contiguous portion of Internet over which consistent set of DS
policies administered
– Typically under control of one administrative entity
Defined in SLA
– Customer may be user organization or other DS domain
– Packet class marked in DS field
Service provider configures forwarding policies routers
– Ongoing measure of performance provided for each class
DS domain expected to provide agreed service internally
If destination in another domain, DS domain attempts to
forward packets through other domains
– Appropriate service level requested from each domain
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SLA ParametersSLA Parameters
Detailed service performance parameters
– Throughput, drop probability, latency
Constraints on ingress and egress points
– Indicate scope of service
Traffic profiles to be adhered to
– Token bucket
Disposition of traffic in excess of profile
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Example ServicesExample Services
Qualitative
– A: Low latency
– B: Low loss
Quantitative
– C: 90% in-profile traffic delivered with no more than
50ms latency
– D: 95% in-profile traffic delivered
Mixed
– E: Twice bandwidth of F
– F: Traffic with drop precedence X has higher delivery
probability than that with drop precedence Y
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DS Field v IPv4 Type of ServiceDS Field v IPv4 Type of Service
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DS Field DetailDS Field Detail
Leftmost 6 bits are DS codepoint
– 64 different classes available
– 3 pools
xxxxx0 : reserved for standards
– 000000 : default packet class
– xxx000 : reserved for backwards compatibility with IPv4 TOS
xxxx11 : reserved for experimental or local use
xxxx01 : reserved for experimental or local use but may be
allocated for future standards if needed
Rightmost 2 bits unused
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Configuration – Interior RoutersConfiguration – Interior Routers
Domain consists of set of contiguous routers
Interpretation of DS codepoints within domain is
consistent
Interior nodes (routers) have simple mechanisms
to handle packets based on codepoints
– Queuing gives preferential treatment depending on
codepoint
Per Hop behaviour (PHB)
Must be available to all routers
Typically the only part implemented in interior routers
– Packet dropping rule dictated which to drop when
buffer saturated
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Configuration – BoundaryConfiguration – Boundary
RoutersRouters
Include PHB rules
Also traffic conditioning to provide desired
service
– Classifier
Separate packets into classes
– Meter
Measure traffic for conformance to profile
– Marker
Policing by remarking codepoints if required
– Shaper
– Dropper
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Per Hop Behaviour –Per Hop Behaviour –
Expedited forwardingExpedited forwarding
Premium service
– Low loss, delay, jitter; assured bandwidth end-to-end
service through domains
– Looks like point to point or leased line
– Difficult to achieve
– Configure nodes so traffic aggregate has well defined
minimum departure rate
EF PHB
– Condition aggregate so arrival rate at any node is
always less that minimum departure rate
Boundary conditioners
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Per Hop Behaviour –Per Hop Behaviour –
Explicit AllocationExplicit Allocation
Superior to best efforts
Does not require reservation of resources
Does not require detailed discrimination among flows
Users offered choice of number of classes
Monitored at boundary node
– In or out depending on matching profile or not
Inside network all traffic treated as single pool of
packets, distinguished only as in or out
Drop out packets before in packets if necessary
Different levels of service because different number of in
packets for each user
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PHB - Assured ForwardingPHB - Assured Forwarding
Four classes defined
– Select one or more to meet requirements
Within class, packets marked by customer
or provider with one of three drop
precedence values
– Used to determine importance when dropping
packets as result of congestion
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Codepoints for AF PHBCodepoints for AF PHB