Introducción QoS in IP based Networks QoS in MANETs Propuestas del Grupo GRC. Arquitectura DACME. QoS in MANETs

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1 Tema 5.- Redes inalámbricas Ad Hoc. Quality of Service (QoS) Introducción QoS in IP based Networks QoS in MANETs Propuestas del Grupo GRC Arquitectura DACME QoS in MANETs Redes Inalámbricas Máster Ingeniería de Computadores 2008/2009

2 MIC 2008/ Introduction The evolution of the Multimedia Technology and the Commercial Interest of Companies to reach civilian applications have made QoS in MANETs an unavoidable 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 possible. MANETs : 3 new problems! Dynamic Topology. Bandwidth Constrains. Limited Processing & Storing capabilities of Devices. What happens with QoS in Wire-based Networks?. Can we port ideas / protocols to MANETs? A Glance At QoS in Mobile Ad-Hoc Networks:

3 MIC 2008/ How do we measure the QoS? Some mostly used QoS attributes Available Bandwidth Probability of packet loss Delay variance (jitter, unpredictable delay) end-to-end delay (Accumulation of jitter along the path) Power consumption or battery charge Service coverage area The QoS Metrics QoS Metrics can be defined in terms of one of the parameters or a set of parameters in varied proportions alámbricas Redes Ina

4 MIC 2008/ QoS definition QoS Definition The collective effect of service performance which h determines the degree of satisfaction of a user of a service. The United Nations Consultative Committee for International Telephony and Telegraph (CCITT) Recommendation E.800 alámbricas Redes Ina Video frame without QoS Support Video frame with QoS Support

5 MIC 2008/ Principles for QOS Guarantees (I) Consider a phone application at 1Mbps and an FTP application Msharing a 1.5 Mbps link. 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 policy to treat packets accordingly. alámbricas Redes Ina

6 MIC 2008/ Principles for QOS Guarantees (II) PRINCIPLE 2: provide protection (isolation) for one class 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: alámbricas Redes Ina

7 MIC 2008/ Principles for QOS Guarantees (III) PRINCIPLE 3: While providing isolation, it is desirable to use Mresources as efficiently as possible. 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. alámbricas Redes Ina

8 MIC 2008/ Principles for QOS Guarantees (IV) PRINCIPLE 4: Need a Call Admission Process; application Mflow declares its needs, network may block call if it cannot satisfy the needs. Remember: Cannot support traffic beyond link capacity alámbricas Redes Ina

9 MIC 2008/ How is QoS achieved? Over Provisioning. Add plentiful capacity to the network. Easy! (e.g. upgrade from 10Mb to 100Mb) Can be done gradually. But we remain at 1 service class (best effort) again. QoS in IP Based Networks 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-less Engineering. (e.g. DiffServ) Used in today s Differentiated Services» IPv4 TOS octect» IPv6 traffic Class octect alámbricas Redes Ina

10 MIC 2008/ Integrated Services Attempt to modify Internet service model to support diverse application requirements Any data flow that desires better than best-effort delivery requests and reserves resources at routers along the path RSVP is the recommended reservation protocol If insufficient resources are available, the flow is denied admission into the network Each router Maintains reservation state for each flow Classifies every packet and decides forwarding behavior Monitors the flow to ensure that it does not consume more than the reserved resources Advantages Enables fine-grained QoS and resource guarantees Disadvantages Not scalable, harder to administer i

11 MIC 2008/ Service Interface & Call Admission Session must first declare its QoS requirement and characterize the Mtraffic it will send through the network R-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 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. alámbricas Redes Ina

12 MIC 2008/ Differentiated Services Moves admission control and flow monitoring to the edge of the Mnetwork service Edge nodes classify and mark packets to receive a particular type of 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 values Advantages More scalable No per-flow state Easier to administer BIG ADVANTAGE: No state info to be maintained by routers! Disadvantages Cannot provide the same per-flow guarantees as IntServ

13 MIC 2008/ Edge Router/Host Functions Classification: marks packets according to classification rules to be specified. Metering: checks whether the traffic falls within the negotiated profile. Marking: marks traffic that falls within profile. Conditioning: delays and then forwards, discards, or remarks other traffic. alámbricas Redes Ina

14 MIC 2008/ QoS in MANETs A lot of work has been done in supporting QoS in the Internet, but Munfortunately none of them can be directly used in MANETs because of the bandwidth constraints and dynamic network topology of MANETs. To 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 circumstances. The resource limitations and the mobility of hosts make things more complicated. Hard QoS guarantee is not possible in MANETs Adaptive QoS Service Differentiation entiation

15 MIC 2008/ Why QoS is Hard in Mobile Ad Hoc Network? Dynamic Network Topology M Flow stop receiving QoS provisions due to path disconnections New paths must be established, causing data loss and delays Imprecise state information Link state changes continuously Flow states change over time No central control for coordination Error-Probe shared medium Hidden terminal problem Limited resources availability Bandwidth, battery Life, Storage, processing capabilities Insecure medium

16 MIC 2008/ Effects of congestion and mobility: PSNR degradation due to mobility Bursty losses Several consecutive frames lost (video freezed) degradation due to congestion Random losses More uniform distortion decay Video at 10Hz 200 seconds interval PSNR: The phrase peak signal-to-noise ratio, often abbreviated PSNR, is an engineering term for the ratio between the maximum possible power of a signal and the power of corrupting noise that t affects the fidelity of its representation. ti The PSNR is most commonly used as a measure of quality of reconstruction in image compression

17 MIC 2008/ Congestion jitter: relatively small frequent variations Effects of congestion and mobility: jitter Mobility jitter: very large peaks occasional occurrences on route change jitter is an abrupt and unwanted variation of one or more signal characteristics

18 MIC 2008/ Main issues The main issues to consider to achieve good quality are: MAC level l QoS: IEEE e required to differentiate t from bandwidth greedy best-effort traffic Admission control: to avoid more connections than the MANET can handle Increase 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 streaming Also H.264 codec tuning: alámbricas Redes Ina

19 MIC 2008/ The first QoS Model proposed in 2000 for MANETs FQMM (Flexible QoS Model for Manet QoS Signalling) QoS Signalling INSIGNIA (in-band signalling) g) drsvp(dynamic RSVP) QoS Routing QoS enabled routing (AODV/OLSR) CEDAR(Core-Extraction Distributed Ad-hoc Routing) Ticket based Probing (distributed QoS routing) QoS MAC IEEE e MACA/PR (Multiple Access Collision Avoidance with Piggyback Reservation) prioritised binary countdown (PBC)... and SWAN: integrated proposal Mona Ghassemian, King s College, September 2003 QoS in MANETs QoS in MANETs

20 MIC 2008/ FQMM FQMM is the first QoS Model proposed in 2000 for MANETs by Xiao et al. The model can be characterized as a hybrid IntServ/DiffServ Model as the highest priority is assigned per-flow provisioning. the rest is assigned per-class provisioning. Three types of nodes: Ingress (transmit) Core (forward) Egress (receive) The role of each node 1 change according to the node mobility Only works with TCP traffic Mona Ghassemian, King s College, September 2003 ingress 2 5 core egress

21 MIC 2008/ QoS Signalling Terminology Signaling is used to reserve and release resources. Prerequisites of QoS Signalling Reliable transfer of signals between routers Correct 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 g can be divided ded into In-band and Out-of-band In-band: integrated in data packets Out-of-band: explicit use of control packets. Performance? This packets should have higher priority RSVP is an example of out-of-band signaling Is the facto signaling protocol for IntServ Most papers support that In-band Signaling is more appropriate for MANETs.

22 MIC 2008/ In-band VS Out-of Band Signaling In-band Signaling, network control information is encapsulated in data packets Lightweight Not Flexible for defining new Service Classes. Version Hdr Len Prec TOS TTL Identification Flags Protocol Source Address Destination Address Options Total Length Fragment Offset Header CheckSum Padding 32 bits (Shaded fields are absent from IPv6 header) Out-of-band Signaling, network control information is carried in separate packets using explicit control packets. Heavyweight signaling packets must have higher priority to achieve on time notification => can lead to complex systems. + Scalability. Signal packets don t rely on data packets +W We can have rich set of services, since we don t need dt to steal l bits from data packets

23 MIC 2008/ INSIGNIA INSIGNIA is the first signaling protocol designed solely for MANETs by Ahn et al 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 Magazine. Can be characterized as an In-band RSVP protocol. It 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 some flows, e.g., video, voice. QoS insensitive flows can be serviced in best effort manner: QoS sensitive flows should be treated in better than best effort manner Mona Ghassemian, King s College, September 2003

24 MIC 2008/ INSIGNIA Review INSIGNIA is just the signaling protocol of a complete QoS MArchitecture. To realize a complete QoS Architecture we also need many other components A Routing Protocol (e.g. DSR, AODV, TORA) to track changes of routes An Admission Control Module to allocate requests according to the requested resources A Packet Scheduling Module A Medium Access Controller Module INSIGNIA Drawbacks. Only 2 classes of services (RT) and (BE). Flow state information must be kept in mobile bl hosts. Georgiadis, Jacquet, and Mans proved that bandwidth reservation on ad-hoc networks is an np-hard problem [1] [1] Bandwidth Reservation in Multihop Wireless Networks: Complexity and Mechanisms. ICDCSW'04, Hachioji - Tokyo, Japan, March 2004.

25 MIC 2008/ QoS Routing QoS in MANETs, an Integrated Vision QoS enabled routing (AODV/OLSR) CEDAR(Core-Extraction Distributed Ad-hoc Routing) Ticket based Probing (distributed ib t d QoS routing) Predictive Location-Based QoS Routing Protocol Bandwidth Routing Protocol Trigger-Based Distributed QoS Routing Protocol On-Demand QoS Routing Protocol QoS-Enabled Ad Hoc On-Demand Distance Vector Routing Protocol On-Demand Link-state Multipath QoS Routing Protocol Asynchronous Slot Allocation Strategies

26 MIC 2008/ QoS Routing Routing is an essential component for QoS. It can inform a source node of the bandwidth and QoS availability of a destination node We know that t AODV is a successful an on-demand d 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 Discovery Process (RREQ). alámbricas Redes Ina Mona Ghassemian, King s College, September 2003

27 MIC 2008/ QoS for AODV 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 to the route messages (RREQ, RREP). A 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 tables AODV current fields. Destination Sequence Number, Interface, Hop Count, Next Hop, List of Precursors AODV new fields. (4 new fields) 1. Maximum Delay, 2. Minimum Available Bandwidth, 3. List of Sources Requesting Delay Guarantees and 4. List of Sources Requesting Bandwidth Guarantees

28 MIC 2008/ QoS information is added to the RREQ packet QoS-Extensions of AODV: Basic Idea Intermediate nodes forward the RREQ only if they have sufficient resources to meet the QoS requirement Resource information is updated d in the RREQ by intermediate nodes S RREQ RREP D Destination sends resource information back to source in the RREP message

29 MIC 2008/ QoS for AODV - Delay Handling Delay with the Maximum Delay extension and the List of Sources Requesting Delay Guarantees. RREQ includes delay Each 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 process. 1 RREQ1 RREQ1 RREQ1 delay=100 delay=70 delay=20 ingress A 2 RREQ2 delay=10 x RREP1 delay=80 core B Traversal_tim e= 3 0 cache delay(b->d)=80 RREP1 delay=50 core C Traversal_time= 5 0 cache delay(c->d)=50 =TraversalTime + delay RREP1 delay=0 egress D

30 MIC 2008/ QoS for AODV Handling Bandwidth is similar to handling Delay requests. M Actually a RREQ can include both types. - Bandwidth Example shows how the with the Minimum Available Bandwidth extension and the List of Sources Requesting Bandwidth Guarantees are utilized during route discovery process. 1 RREQ1 min_bandwidth=10kbps RREQ1 min_bandwidth=10kbps RREQ1 min_bandwidth=10kbps ingress A 2 RREQ2 minband=80k x RREP1 bandwidth=50 core B Available_Bandwidth = 100K cache band(b->d)=50 RREP1 bandwidth=50 core C Available_Bandwidth = 50K cache band(c->d)=50 min{inf,50} RREP1 bandwidth=inf egress D

31 MIC 2008/ Loosing Quality of Service Parameters QoS for AODV - Loosing QoS if after establishment ta node detects t that tthe QoS can t tbe maintained i 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? ingress A cache delay(b->d)=80 QOS_LOST core B Traversal_time= 3 0 cache delay(b->d)=80 QOS_LOST core C Traversal_time= 5 0 cache delay(c->d)=50 egress D

32 MIC 2008/ QoS MAC IEEE e Cluster TDMA QoS in MANETs, an Integrated Vision MACA/PR. (Multiple Access Collision Avoidance with Piggyback Reservation) Prioritised binary countdown (PBC) alámbricas Redes Ina

33 MIC 2008/ Stateless Wireless Ad-hoc Networks... and SWAN: integrated proposalp intermediate t nodes don t keep per-flow or aggregate state t information differentiate real-time and best-effort effort traffic QoS-capable MAC not needed AIMD algorithm (+ * - like TCP window) Uses feedback information (ECN explicit congestion notification) Principles: Rate control: per-hop MAC delay measurements Source-based admission control implemented in ns-2 and Linux/AODV

34 MIC 2008/ Propuestas del Grupo GRC: Arquitectura DACME Previous proposals have strong requirements: All terminals must be equipped with the same software and similar hardware All terminals must perform QoS related tasks If some of the terminals do not offer QoS support, the whole QoS framework fails or there is severe malfunctioning None of the previous proposals has taken into consideration that: t The bandwidth reservation process is NP-hard QoS at the MAC layer is fundamental Multipath routing algorithms can offer important benefits The MANET paradigm is based on user cooperation, but in most cases we can not force users to cooperate

35 MIC 2008/ Propuestas del Grupo GRC: Arquitectura DACME Propuestas del Grupo GRC Arquitectura DACME Multipath routing algorithm [1] TCP/UDP IP MDSR IEEE e DACME Distributed admission control Prioritized channel access IEEE g

36 MIC 2008/ Only two: DACME - Requirements All stations that have IEEE e interfaces should map the IP packet's TOS to a MAC-level l Access Category (basic requirement to achieve good performance) Sources and destinations of QoS traffic should implement DACME (Distributed Admission Control for MANET Environments) alámbricas Redes Ina

37 MIC 2008/ DACME - Admission control DACME makes periodic end-to-end network measurements using probes Intermediate 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 alámbricas Redes Ina

38 MIC 2008/ DACME architecture 1. The application registers with DACME, indicating the source and destination port, the destination'ss IP address and the QoS requirements 2. DACME periodically sends probes to assess available bandwidth on the path 3. The port state is set to up or down according to current network conditions 4. The packet filter module is responsible for enforcing accept/reject decisions, and also for changing the packet's TOS field if accepted alámbricas Redes Ina

39 MIC 2008/ End-to-end bandwidth estimation Is based on measurements made every 3 seconds (±0.5 s of jitter) 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) Source Destination Probe t 0... X t rec n timeout Probe reply Adjustment of these values at the source (over-estimation)

40 MIC 2008/ General simulation setup: ns-2 2discrete event simulator Radio interfaces are IEEE g/e enabled Performance evaluation Scenarios are sized 1900x400 m2 and composed by 50 nodes Radio range is of 250 meters (4 hops between nodes on average) Nodes move according to the random way-point model at a constant speed of 5 m/s Comparison between DSR & MDSR routing protocols Simulation time is of 300 seconds for each experiment DACME source/destination pairs have a DACME agent attached

41 MIC 2008/ Video sources and 3 Voice sources regulated by DACME Video sources generate CBR traffic at 1 Mbit/s in the Video AC Voice sources: VoIP streams simulated using a Pareto On/Off distribution both burst and idle time set to 500 ms shaping factor used is 1.5, average data rate is of 100 kbit/s Sources are turned off in the same order they were turned on 4 background traffic sources Traffic is negative-exponentially distributed Traffic Variable traffic loads; load share per AC is: 50% to the Video AC, 25% to Besteffort AC, 25% to Background AC These sources are active all the time

42 MIC 2008/ Performance in terms of throughput/losses On average the throughput of DACME-regulated sources is much Mmore stable (always close to the source data rate of 1 Mbit/s) s Voice sources do not generate constant data-rate traffic In terms of packet losses we achieve very significant improvements

43 MIC 2008/ Performance in terms of end-to-end delay In terms of average end-to-end delay, DACME allows achieving much lower values than its non-dacme counterpart alámbricas Redes Ina

44 MIC 2008/ Routing overhead and traffic acceptance rate In terms of routing overhead, DACME reduces it by avoiding routing collapse situations In terms of traffic acceptance rate: high data-rate sources (video) are more penalized

45 MIC 2008/ Conclusions and future work We introduced a new paradigm of QoS architecture for MANETs based on distributed admission control that is able to adapt to the different constrains of MANET environments Simulation results show that DACME: Improves the support of multimedia applications by achieving more stable throughput, fewer packet losses and reduced end-to-end delay 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 Linux operating system to deploy an IEEE e-based real-life testbed In linux system DACME can be implemented using Iptables alámbricas Redes Ina