Tema 2.- Redes inalámbricas Ad Hoc. Tema 2.- Redes inalámbricas Ad Hoc. Quality of Service (QoS)Quality of Service (QoS)

IntroducciónQoS in IP based NetworksQoS in MANETs Propuestas del Grupo GRC

Arquitectura DACME

QoS in QoS in

Redes Inalámbricas Ad Hoc Máster Ingeniería de Telecomunicación, Universidad de Málaga 2008/2009Redes Inalámbricas Ad Hoc Máster Ingeniería de Telecomunicación, Universidad de Málaga 2008/2009

QoS in MANETsQMANETs

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2Introduction

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The evolution of the Multimedia Technology and the Commercial Interest of Companies to reach civilian applications have made QoS in MANETs an unavoidable taskM task.

QoS and Overhead are synonyms ☺!. The idea of providing QoS in MANETs is not to extinct Overhead but to keep it as low as possibleextinct Overhead but to keep it as low as possible.

MANETs : 3 new problems!D i T lDynamic Topology.Bandwidth Constrains.Limited Processing & Storing capabilities of Devices.

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What happens with QoS in Wire-based Networks?. Can we port ideas / protocols to MANETs?

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A Glance At QoS in Mobile Ad-Hoc Networks: http:/www.cs.ucr.edu/~csyiazti/cs260.html

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3The QoS Metrics

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How do we measure the QoS ?Some mostly used QoS attributesM Some mostly used QoS attributes

Available BandwidthProbability of packet lossy pDelay variance (jitter, unpredictable delay)end-to-end delay (Accumulation of jitter along the path)Power consumption or battery chargeService coverage area

QoS Metrics can be defined in terms of one of the parameters or aQoS Metrics can be defined in terms of one of the parameters or a set of parameters in varied proportions

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4QoS Definition

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QoS definition“Th ll ti ff t f i f hi h d t i thM “The collective effect of service performance which determines the degree of satisfaction of a user of a service”.

The United Nations Consultative Committee for International Telephony andThe United Nations Consultative Committee for International Telephony and Telegraph (CCITT) Recommendation E.800

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Video frame without QoS Support Video frame with QoS Support

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5Principles for QOS Guarantees (I)

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Consider a phone application at 1Mbps and an FTP application sharing a 1.5 Mbps link. M g p

Bursts of FTP can congest the router and cause audio packets to be dropped.Want to give priority to audio over FTP.

PRINCIPLE 1: Marking of packets is needed for router to distinguish between different classes; and new router policydistinguish between different classes; and new router policy to treat packets accordingly.

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6Principles for QOS Guarantees (II)

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PRINCIPLE 2: provide protection (isolation) for one class from other classesM from other classes.

Applications misbehave (audio sends packets at a rate higher than 1Mbps assumed above).Require Policing Mechanisms to ensure sources adhere to bandwidth requirements; Marking and Policing need to be done at the edges:

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7Principles for QOS Guarantees (III)

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PRINCIPLE 3: While providing isolation, it is desirable to use resources as efficiently as possible.M y p

Alternative to Marking and Policing: allocate a set portion of bandwidth to each application flow; can lead to inefficient use of bandwidth if one of the flows does not use its allocation.

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8Principles for QOS Guarantees (IV)

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PRINCIPLE 4: Need a Call Admission Process; application flow declares its needs, network may block call if it cannot M , ysatisfy the needs .

Remember: Cannot support traffic beyond link capacity

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9QoS in IP Based Networks

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How is QoS achieved? “Over Provisioning”. Add plentiful capacity to the network.

M Easy! (e.g. upgrade from 10Mb to 100Mb)Can be done gradually.But we remain at 1 service class (best effort) again.

“Network Traffic Engineering”. Make the Network more sophisticated!(e.g. Traffic Classes, Connection Admission Control, Policy Managers,…)

Reservation-based Engineering (e g RSVP/IntServ ATM)Reservation-based Engineering. (e.g. RSVP/IntServ, ATM)Reservation-less Engineering. (e.g. DiffServ)

– Used in today’s Differentiated Services» IPv4 TOS octect» IPv6 traffic Class octect

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10Integrated Services

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Attempt to modify Internet service model to support diverse application requirementsM application requirementsAny data flow that desires better than best-effort delivery requests and reserves resources at routers along the pathg p

RSVP is the recommended reservation protocol

If insufficient resources are available, the flow is denied admission into the networkEach router

f h flMaintains reservation state for each flow Classifies every packet and decides forwarding behaviorMonitors the flow to ensure that it does not consume more than the reserved

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Monitors the flow to ensure that it does not consume more than the reserved resources

Advantages

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DisadvantagesN t l bl h d t d i i t

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Not scalable, harder to administer

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11Service Interface & Call Admission

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Session must first declare its QoS requirement and characterize the traffic it will send through the networkM gR-spec: defines the QoS being requested by receiver (e.g., rate r)T-spec: defines the traffic characteristics of sender (e.g., leaky bucket with rate r and buffer size b).A signaling protocol is needed to carry the R-spec and T-spec to the routers where reservation is required; RSVP is a leading candidate forrouters where reservation is required; RSVP is a leading candidate for such signaling protocol.Call Admission: routers will admit calls based on their R-spec and T-spec and base on the current resource allocated at the routers to other calls.

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12Differentiated Services

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Moves admission control and flow monitoring to the edge of the networkM

Edge nodes classify and mark packets to receive a particular type of service

Diff S C d P i t (DSCP)Diff Serv Code Point (DSCP)Packet is marked in the Type of Service (TOS) in IPv4, and Traffic Class in IPv6.

Finite set of DSCPs defined

Interior nodes determine the type of service for forwarded packets based on their DSCP valuesbased on their DSCP valuesAdvantages

More scalable

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No per-flow stateEasier to administer

BIG ADVANTAGE:

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Disadvantages

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Cannot provide the same per-flow guarantees as IntServ

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13Edge Router/Host Functions

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Classification: marks packets according to classification rules to be specifiedM be specified.Metering: checks whether the traffic falls within the negotiated profileprofile.Marking: marks traffic that falls within profile.Conditioning: delays and then forwards discards or remarksConditioning: delays and then forwards, discards, or remarks other traffic.

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14QoS in MANETs

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A lot of work has been done in supporting QoS in the Internet, but unfortunately none of them can be directly used in MANETs because M y yof the bandwidth constraints and dynamic network topology of MANETs.To support QoS the link state information such as delay bandwidthTo support QoS, the link state information such as delay, bandwidth, cost, loss rate, and error rate in the network should be available and manageable.However, getting and managing the link state information in MANETs is very difficult because the quality of a wireless link is apt to change with the surrounding circumstanceswith the surrounding circumstances. The resource limitations and the mobility of hosts make things more complicated.

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pHard QoS guarantee is not possible in MANETs

Adaptive QoSSe ice Diffe entiation

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15Why QoS is Hard in Mobile Ad Hoc Network?

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Dynamic Network TopologyFlow stop receiving QoS provisions due to path disconnectionsM Flow stop receiving QoS provisions due to path disconnectionsNew paths must be established, causing data loss and delays

Imprecise state informationk h lLink state changes continuously

Flow states change over timeNo central control for coordinationNo central control for coordinationError-Probe shared mediumHidden terminal problempLimited resources availability

Bandwidth, battery Life, Storage, processing capabilitiesI di

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Insecure medium

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16Effects of congestion and mobility: PSNR

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B t l

degradation due to mobility

M Bursty losses

Several consecutive frames lost (videoframes lost (video freezed)

Random losses

degradation due to congestion

Random losses

More uniform distortion decay

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Video at 10Hz → 200 seconds interval

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PSNR: The phrase peak signal-to-noise ratio, often abbreviated PSNR, is an engineering term for the ratio between the i ibl f i l d th f ti i th t ff t th fid lit f it t ti

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The PSNR is most commonly used as a measure of quality of reconstruction in image compression

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17Effects of congestion and mobility: jitter

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Congestion jitter:

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g j

relatively small

frequent variationsfrequent variations

Mobility jitter:Mobility jitter:

very large peaks

i loccasional occurrences on route change

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jitter is an abrupt and unwanted variation of one or more signal characteristics

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18Main issues

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The main issues to consider to achieve good quality are: MAC l l Q S IEEE 802 11 i d t diff ti t fM MAC level QoS: IEEE 802.11e required to differentiate from bandwidth greedy best-effort trafficAdmission control: to avoid more connections than the MANETAdmission control: to avoid more connections than the MANET can handleIncrease routing effectiveness: even by using layer-2 awareIncrease routing effectiveness: even by using layer 2 aware routing protocols such as AODV or DSR, video transmission gaps are still too large to be handled by a video codec

For video streamingAlso H.264 codec tuning:

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19QoS in MANETs

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The first QoS Model proposed in 2000 for MANETsFQMM (Flexible QoS Model for Manet QoS Signalling)M FQMM (Flexible QoS Model for Manet QoS Signalling)

QoS SignallingINSIGNIA (in-band signalling)( g g)dRSVP(dynamic RSVP)

QoS RoutingQoS enabled routing (AODV/OLSR)CEDAR(Core-Extraction Distributed Ad-hoc Routing)Ticket based Probing (distributed QoS routing)Ticket based Probing (distributed QoS routing)

QoS MACIEEE 802.11e

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IEEE 802.11eMACA/PR

(Multiple Access Collision Avoidance with Piggyback Reservation) QoS in

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prioritised binary countdown (PBC)

... and

QoS in MANETs

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SWAN: integrated proposalMona Ghassemian, King’s College, September 2003

MANETs

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20FQMM

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FQMM is the first QoS Model proposed in 2000 for MANETs by Xiao et alM by Xiao et al.The model can be characterized as a “hybrid” I tS /DiffS M d lIntServ/DiffServ Model as

the highest priority is assigned per-flow provisioning.h d lthe rest is assigned per-class provisioning.

Three types of nodes:Ingress (transmit)Core (forward)

core

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Only works with TCP traffic5

6 7egress

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Mona Ghassemian, King’s College, September 2003

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21QoS Signalling Terminology

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Signaling is used to reserve and release resources.

M

Prerequisites of QoS SignallingReliable transfer of signals between routersCorrect Interpretation and activation of the appropriate mechanisms to handle the signal.

It means that signaling must be understandable and implemented by the rest of the nodes

Signaling can be divided into “In-band” and “Out-of-band”S g a g ca be d ded to ba d a d Out o ba dIn-band: integrated in data packetsOut-of-band: explicit use of control packets. Performance?

This packets should have higher priority

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This packets should have higher priority RSVP is an example of out-of-band signaling

– Is the facto signaling protocol for IntServ

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Most papers support that “In-band” Signaling is more appropriate for MANETs.

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22 In-band VS Out-of Band SignalingM

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In-band Signaling, network control information is encapsulated in data packetsM packets

LightweightNot Flexible for defining new Service Classes.

TTL Header CheckSumFragment Offset

Total LengthIdentification

ProtocolFlags

Version Hdr Len Prec TOS

Source AddressDestination Address

Options Padding

Out-of-band Signaling network control information is carried in separate

32 bits(Shaded fields are absent from IPv6 header)

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Out-of-band Signaling, network control information is carried in separate packets using explicit control packets.

Heavyweightsignaling packets must have higher priority to achieve on time notification > can

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+ Scalability. Signal packets don’t rely on data packets+ W h i h t f i i d ’t d t “ t l“ bit f d t

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packets

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23INSIGNIA

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INSIGNIA is the first signaling protocol designed solely for MANETs by Ahn et al 1998M by Ahn et al. 1998.

Lee, S.B., Ahn, G.S., Campbell, A.T., "Improving UDP and TCP Performance in Mobile Ad Hoc Networks with INSIGNIA", June 2001, IEEE Communication M iMagazine.

Can be characterized as an “In-band RSVP” protocol.It encapsulates control info in the IP Option field (called now INSIGNIA OptionIt encapsulates control info in the IP Option field (called now INSIGNIA Option field). (IN-BAND)It keeps flow state for the real time (RT) flows. (RSVP)It is “Soft State”. The argument is that assurance that resources are released is more important than overhead that anyway exists. (RSVP)

INSIGNA tries to provide something better than best effort service for

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INSIGNA tries to provide something better than best effort service for some flows, e.g., video, voice.

QoS insensitive flows can be serviced in best effort manner: e-mail

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QoS sensitive flows should be treated in better than best effort manner

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24INSIGNIA Review

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INSIGNIA is just the signaling protocol of a complete QoS Architecture.M

To realize a complete QoS Architecture we also need many other components

A Routing Protocol (e g DSR AODV TORA) to track changes of routesA Routing Protocol (e.g. DSR, AODV, TORA) to track changes of routesAn Admission Control Module to allocate requests according to the requested resourcesA Packet Scheduling ModulegA Medium Access Controller Module

INSIGNIA Drawbacks.Only 2 classes of services (RT) and (BE).l f b k b l h

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Flow state information must be kept in mobile hosts.Georgiadis, Jacquet, and Mans proved that bandwidth reservation on ad-hoc networks is an np-hard problem [1]

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[1] “Bandwidth Reservation in Multihop Wireless Networks: Complexity and Mechanisms”. ICDCSW'04, Hachioji - Tokyo, Japan, March 2004.

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25QoS in MANETs, an Integrated Vision

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QoS RoutingQ S bl d ti (AODV/OLSR)M QoS enabled routing (AODV/OLSR)CEDAR(Core-Extraction Distributed Ad-hoc Routing)Ti k t b d P bi (di t ib t d Q S ti )Ticket based Probing (distributed QoS routing)Predictive Location-Based QoS Routing ProtocolB d idth R ti P t lBandwidth Routing ProtocolTrigger-Based Distributed QoS Routing ProtocolOn Demand QoS Routing ProtocolOn-Demand QoS Routing ProtocolQoS-Enabled Ad Hoc On-Demand Distance Vector Routing Protocol

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ProtocolOn-Demand Link-state Multipath QoS Routing ProtocolAsynchronous Slot Allocation Strategies

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26QoS Routing

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Routing is an essential component for QoS. It can inform a source node of the bandwidth and QoS availability of aM source node of the bandwidth and QoS availability of a destination nodeW k th t AODV i f l d d tiWe know that AODV is a successful an on-demand routing protocol based on the ideas of both DSDV and DSR.We also know that when a node in AODV desires to send a message to some destination node it initiates a Route Di P (RREQ)Discovery Process (RREQ).

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27QoS for AODV

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QoS for AODV was proposed in 2000 by C. Perkins and E. Royer.The main idea of making AODV QoS enabled is to add extensions toM The main idea of making AODV QoS enabled is to add extensions to the route messages (RREQ, RREP).A node that receives a RREQ + QoS Extension must be able to meetA node that receives a RREQ + QoS Extension must be able to meet the service requirement in order to rebroadcast the RREQ (if not in cache).In order to handle the QoS extensions some changes need to be on the routing tablesAODV current fields.

Destination Sequence Number, Interface, Hop Count, Next Hop, List of Precursors

AODV new fields (4 new fields)

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AODV new fields. (4 new fields)1. Maximum Delay, 2. Minimum Available Bandwidth,

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,3. List of Sources Requesting Delay Guarantees and 4. List of Sources Requesting Bandwidth Guarantees

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28QoS-Extensions of AODV: Basic Idea

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QoS information is added to the RREQ packetM RREQ packet

Intermediate nodes forward theIntermediate nodes forward the RREQ only if they have sufficient resources to meet the S DQoS requirementResource information is

d t d i th RREQ b

S

RREQupdated in the RREQ by intermediate nodes

RREQRREP

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Destination sends resource information back to source in

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information back to source in the RREP message

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29QoS for AODV - Delay

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Handling Delay with the Maximum Delay extension and the List of Sources Requesting Delay Guarantees.

RREQ i l d d lM RREQ includes delayEach node has its NODE_TRANSVERSAL_TIME

Example shows how the with the Maximum Delay extension and the List of Sources Requesting Delay Guarantees are utilized during route discovery q g y g yprocess.

RREQ1 RREQ1 RREQ11

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Traversal_tim e= 3 0

delay=100

egressD

delay=70 delay=20

2x

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cachedelay (C->D)=50 =TraversalTime+ delay

A D

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cachedelay (B->D)=80

RREP1RREP1

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delay=0RREP1delay=50delay=80

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30QoS for AODV - Bandwidth

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Handling Bandwidth is similar to handling Delay requests. Actually a RREQ can include both typesM Actually a RREQ can include both types.

Example shows how the with the Minimum Available Bandwidth extension and the List of Sources Requesting Bandwidth Guarantees are utilized during route discovery processGuarantees are utilized during route discovery process.

RREQ1min_bandwidth=10Kbps

RREQ1min_bandwidth=10Kbps

RREQ1min_bandwidth=10Kbps

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egressD

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cacheband(B->D)=50

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bandwidth=50RREP1

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31QoS for AODV - Loosing QoS

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Loosing Quality of Service Parametersif ft t bli h t d d t t th t th Q S ’t b i t i d itM if after establishment a node detects that the QoS can’t be maintained any more it originates a ICMP QOS_LOST message, to all depending nodes.== > Reason why we keep a List of Sources Requesting Delay/Bandwidth Guarantees.

Reasons for loosing QoS Parameters.Increased Load of a node. Why would a node take over more jobs that it can handle?

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cachedelay(B->D)=80

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QOS_LOSTQOS_LOST

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32QoS in MANETs, an Integrated Vision

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QoS MACIEEE 802 11M IEEE 802.11eCluster TDMAMACA/PRMACA/PR. (Multiple Access Collision Avoidance with Piggyback Reservation)Prioritised binary countdown (PBC)…

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33 ... andSWAN: integrated proposal

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g p p

Stateless Wireless Ad-hoc Networksi t di t d d ’t k fl t t tM intermediate nodes don’t keep per-flow or aggregate state information

differentiate real time and best effort trafficdifferentiate real-time and best-effort trafficQoS-capable MAC not needed

↑ ↓AIMD algorithm (+↑ * ↓ - like TCP window)Uses feedback information (ECN – explicit congestion ( p gnotification)

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http://comet.ctr.columbia.edu/swan/

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34Propuestas del Grupo GRC: Arquitectura DACME

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Previous proposals have strong requirements:All terminals must be equipped with the same software and similar hardwareM All terminals must be equipped with the same software and similar hardwareAll terminals must perform QoS related tasksIf some of the terminals do not offer QoS support, the whole QoS framework fails or there is severe malfunctioning

N f th i l h t k i t id ti th tNone of the previous proposals has taken into consideration that:The bandwidth reservation process is NP-hardQoS at the MAC layer is fundamentalQoS at the MAC layer is fundamentalMultipath routing algorithms can offer important benefitsThe MANET paradigm is based on user cooperation, but in most cases we can

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35Propuestas del Grupo GRC: Arquitectura DACME

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Propuestas del Grupo GRCArquitectura DACMEM Arquitectura DACME

TCP/UDP

IP DACM

E

TCP/UDP

Distributed admission controlIP

MDSR

D

Multipath routing l ith [1]

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algorithm [1]

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36DACME - Requirements

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Only two:

M

All stations that have IEEE 802.11e interfaces should map the IP k t' TOS t MAC l l A C t (b i i tpacket's TOS to a MAC-level Access Category (basic requirement

to achieve good performance)

Sources and destinations of QoS traffic should implement DACME (Distributed Admission Control for MANET Environments)(Distributed Admission Control for MANET Environments)

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37DACME - Admission control

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DACME makes periodic end-to-end network measurements using probesM probesIntermediate stations are not aware of DACME's tasks

DACME uses UDP/IP/

Decisions on whether to admit, maintain or drop a QoS flow are based on DACME's periodic measurements and the QoS requirements of each specific flow

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38DACME architecture

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1. The application registers with DACME, indicating the source and destination port the destination's IP address and the QoS requirementsM destination port, the destination s IP address and the QoS requirements

2. DACME periodically sends probes to assess available bandwidth on the pathp3. The port state is set to up or down according to current network conditions4. The packet filter module is responsible for enforcing accept/reject decisions, and also for changing the packet's TOS field if accepted

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39End-to-end bandwidth estimation

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Is based on measurements made every 3 seconds (±0.5 s of jitter)each probe consists of 10 back to back packets with the sameM each probe consists of 10 back-to-back packets with the same TOS/AC as the application's packets to avoid the stolen bandwidth problem (Breslau et al., SIGCOMM 2000)p ( , )

∆t→0

Source Destination

1

...

∆tX

1

2Probe

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Probe replytimeout

Adjustment of these values at the source (over-estimation)

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40Performance evaluation

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General simulation setup:2 di t t i l tM ns-2 discrete event simulator

Radio interfaces are IEEE 802.11g/e enabledS i i d 1900 400 2 d d b 50 dScenarios are sized 1900x400 m2 and composed by 50 nodesRadio range is of 250 meters (4 hops between nodes on average)N d di t th d i t d l tNodes move according to the random way-point model at a constant speed of 5 m/sComparison between DSR & MDSR routing protocolsComparison between DSR & MDSR routing protocolsSimulation time is of 300 seconds for each experimentDACME source/destination pairs have a DACME agent attached

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DACME source/destination pairs have a DACME agent attached

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41Traffic

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4 Video sources and 3 Voice sources regulated by DACMEVideo sources generate CBR traffic at 1 Mbit/s in the Video ACM Video sources generate CBR traffic at 1 Mbit/s in the Video ACVoice sources:

VoIP streams simulated using a Pareto On/Off distribution both burst and idle time set to 500 msshaping factor used is 1.5, average data rate is of 100 kbit/s

Sources are turned off in the same order they were turned onSources are turned off in the same order they were turned on

4 background traffic sourcesTraffic is negative-exponentially distributedVariable traffic loads; load share per AC is: 50% to the Video AC, 25% to Best-effort AC, 25% to Background ACThese sources are active all the time

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These sources are active all the time

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42Performance in terms of throughput/losses

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On average the throughput of DACME-regulated sources is much more stable (always close to the source data rate of 1 Mbit/s)M more stable (always close to the source data rate of 1 Mbit/s)

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Voice sources do not generate constant data-rate traffic

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Voice sources do not generate constant data rate trafficIn terms of packet losses we achieve very significant improvements

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43Performance in terms of end-to-end delay

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In terms of average end-to-end delay, DACME allows achieving much lower values than its non-DACME counterpartM lower values than its non DACME counterpart

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44Routing overhead and traffic acceptance rate

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In terms of routing overhead, DACME reduces it by avoiding routing collapse situationsM collapse situations

In terms of traffic acceptance rate:

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45Conclusions and future work

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We introduced a new paradigm of QoS architecture for MANETs based on distributed admission control that is able to adapt to theM based on distributed admission control that is able to adapt to the different constrains of MANET environmentsSimulation results show that DACME:

Improves the support of multimedia applications by achieving more stable throughput, fewer packet losses and reduced end-to-end delayDoes not misbehave when combined with a multipath routing protocol (MDSR)Does not misbehave when combined with a multipath routing protocol (MDSR)Promotes routing stability and efficient usage of the radio channel

In the future we plan to develop a version of DACME for the LinuxIn the future we plan to develop a version of DACME for the Linux operating system to deploy an IEEE 802.11e-based real-life testbed

In linux system DACME can be implemented using Iptables

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