Difference between integrated services and differentiated services

cisco qos intserv diffserv and differentiated services vs integrated services and elements of computer networking an integrated approach pdf
Dr.ShivJindal Profile Pic
Dr.ShivJindal,India,Teacher
Published Date:19-07-2017
Your Website URL(Optional)
Comment
Better-than-best-effort: QoS, IntServ, DiffServ, RSVP, RTP Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 1Overview  Why better-than-best-effort (QoS-enabled) Internet ?  Quality of Service (QoS) building blocks  End-to-end protocols: RTP, H.323  Network protocols:  Integrated Services(IntServ), RSVP.  Scalable differentiated services: DiffServ  Control plane: QoS routing, traffic engineering, policy management, pricing models Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 2Why Better-than-Best-Effort (QoS)?  To support a wider range of applications Real-time, Multimedia, etc  To develop sustainable economic models and new private networking services Current flat priced models, and best-effort services do not cut it for businesses Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 3Quality of Service: What is it? Multimedia applications: network audio and video QoS network provides application with level of performance needed for application to function. Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 4What is QoS?  “Better performance” as described by a set of parameters or measured by a set of metrics.  Generic parameters: Bandwidth Delay, Delay-jitter Packet loss rate (or loss probability)  Transport/Application-specific parameters: Timeouts Percentage of “important” packets lost Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 5What is QoS (contd) ?  These parameters can be measured at several granularities: “micro” flow, aggregate flow, population.  QoS considered “better” if a) more parameters can be specified b) QoS can be specified at a fine-granularity.  QoS spectrum: Best Effort Leased Line Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 6Fundamental Problems Scheduling Discipline FIFO B B  In a FIFO service discipline, the performance assigned to one flow is convoluted with the arrivals of packets from all other flows  Cant get QoS with a “free-for-all”  Need to use new scheduling disciplines which provide “isolation” of performance from arrival rates of background traffic Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 7Fundamental Problems  Conservation Law (Kleinrock): (i)W (i) = K q  Irrespective of scheduling discipline chosen:  Average backlog (delay) is constant  Average bandwidth is constant  Zero-sum game = need to “set-aside” resources for premium services Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 8QoS Big Picture: Control/Data Planes Control Plane: Signaling + Admission Control or SLA (Contracting) + Provisioning/Traffic Engineering Router Workstation Router Router Workstation Internetwork or WAN Data Plane: Traffic conditioning (shaping, policing, marking etc) + Traffic Classification + Scheduling, Buffer management Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 9QoS Components  QoS = set aside resources for premium services  QoS components: a) Specification of premium services: (service/service level agreement design) b) How much resources to set aside? (admission control/provisioning) c) How to ensure network resource utilization, do load balancing, flexibly manage traffic aggregates and paths ? (QoS routing, traffic engineering) Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 10QoS Components (Continued) d) How to actually set aside these resources in a distributed manner ? (signaling, provisioning, policy) e) How to deliver the service when the traffic actually comes in (claim/police resources)? (traffic shaping, classification, scheduling) f) How to monitor quality, account and price these services? (network mgmt, accounting, billing, pricing) Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 11How to upgrade the Internet for QoS?  Approach: de-couple end-system evolution from network evolution  End-to-end protocols: RTP, H.323 etc to spur the growth of adaptive multimedia applications Assume best-effort or better-than-best-effort clouds  Network protocols: IntServ, DiffServ, RSVP, MPLS, COPS … To support better-than-best-effort capabilities at the network (IP) level Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 12QOS SPECIFICATION, TRAFFIC, SERVICE CHARACTERIZATION, BASIC MECHANISMS Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 13Service Specification  Loss: probability that a flow‟s packet is lost  Delay: time it takes a packet‟s flow to get from source to destination  Delay jitter: maximum difference between the delays experienced by two packets of the flow  Bandwidth: maximum rate at which the soource can send traffic  QoS spectrum: Best Effort Leased Line Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 14Hard Real Time: Guaranteed Services  Service contract Network to client: guarantee a deterministic upper bound on delay for each packet in a session Client to network: the session does not send more than it specifies  Algorithm support Admission control based on worst-case analysis Per flow classification/scheduling at routers Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 15Soft Real Time: Controlled Load Service  Service contract: Network to client: similar performance as an unloaded best-effort network Client to network: the session does not send more than it specifies  Algorithm Support Admission control based on measurement of aggregates Scheduling for aggregate possible Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 16Traffic and Service Characterization  To quantify a service one has two know Flow‟s traffic arrival Service provided by the router, i.e., resources reserved at each router  Examples: Traffic characterization: token bucket Service provided by router: fix rate and fix buffer space  Characterized by a service model (service curve framework) Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 17Token Bucket  Characterized by three parameters (b, r, R) b – token depth r – average arrival rate R – maximum arrival rate (e.g., R link capacity)  A bit is transmitted only when there is an available token When a bit is transmitted exactly one token is consumed r tokens per second bits slope r bR/(R-r) b tokens slope R = R bps time Shivkumar Kalyanaraman Rensselaer Polytechnic Institute regulator 18Characterizing a Source by Token Bucket  Arrival curve – maximum amount of bits transmitted by time t  Use token bucket to bound the arrival curve bps bits Arrival curve time time Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 19Example  Arrival curve – maximum amount of bits transmitted by time t  Use token bucket to bound the arrival curve (b=1,r=1,R=2) Arrival curve bits 4 bps 3 2 2 1 1 0 1 2 3 4 5 1 2 3 4 5 time size of time interval Shivkumar Kalyanaraman Rensselaer Polytechnic Institute 20