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Quality of Service in IP Networks

Join the seminar presented by John Railsback and Rick Blum to delve into QoS research, technologies, and the future direction of QoS for IP networks. Explore the importance of QoS implementation, QoS technologies, and contributing factors. Learn about DiffServ, RSVP, and building blocks like packet classification and per hop behaviors. Uncover the significance of traffic conditioning, AF classes, and expedited forwarding in enhancing network performance.

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Quality of Service in IP Networks

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  1. Lucent Worldwide Services Knowledge Seminars Quality of Service in IP Networks Sharing the Knowledge Behind the Network Presented by: John Railsback jrailsback@lucent.com Rick Blum rickblum@lucent.com

  2. Background • Lucent Worldwide Services is a provider of communications consulting, intelligent maintenance, and management solutions for next generation networks • Seminar objectives • Present the major factors driving QoS • Highlight current QoS technologies and techniques • Provide insight into the future direction of QoS for IP networks

  3. QoS Research • Web-based industry survey conducted September 2000 • 108 respondents • Represent a cross-section of end-user organizations and network solutions providers • Survey report available at www.lucentnps.com/surveys

  4. QoS Definition • Management of available bandwidth to deliver consistent, predictable data (packets) over an IP-based network in terms of: • Latency - delay that an application can tolerate in delivering a packet of data • Jitter - variation in latency • Loss - percentage of lost data • Throughput - amount of data carried • Availability - network uptime

  5. Importance of Implementing/ Improving QoS

  6. The IP Network Problem • Congestion continues to plague the Internet • Traffic expands = or > bandwidth • ”Best-effort" performance dictated by the very design of the Internet Protocol (IP) • Mission critical applications, e.g., IP Telephony and ERP, require prioritization • Service Level Agreements (SLAs) expected • Customer expectations increase with bandwidth

  7. Why QoS • Over-provisioning bandwidth not cost effective in the long run • Users will consume bandwidth as fast as produced • Need reliable data delivery • Mission critical applications • ERP, SAP, Financial Market data • High bandwidth, low latency applications • Video and audio streaming, video conferencing, voice • Provide value-added services with SLAs

  8. Contributing Factors to Importance of QoS

  9. QoS Technologies • Reservation • Allocates resources on a per-flow basis • Flows include information such as transport protocol, source address & port, destination address and port • Intserv/RSVP • Prioritization • Traffic flows are aggregated and categorized by "class of service” • DiffServ and IEEE 802.1p

  10. Integrated Services • Defined in RFCs 2205, 2206- www.ietf.org/rfc.html • Implemented by four components • Signaling protocol (RSVP) • Reserves resources and establishes paths before transmitting data • Admission control routine • Determines whether a request for resources can be granted • Classifier • Places packets in specific queues based on classification result • Packet scheduler • Schedules the packet to meet its QoS requirements

  11. RSVP • Signaling protocol that can operate in "native mode" or "encapsulated mode" within a UDP header • Operates in tandem with either a TCP or UDP "flow" to reserve resources among RSVP-enabled routers • Also being used to signal QoS into DiffServ and MPLS networks

  12. RSVP Request

  13. Differentiated Services (DiffServ) • Defined in RFCs 2474, 2475 • Creates classes of service for traffic flows with different priorities • Aggregates large numbers of individual flows at the edge of the network into small numbers of aggregated flows through the core of the network • Flows are marked at network edge in the IPv4 ToS field (DS field). • Services applied through the core

  14. Building Blocks of DiffServ • Packet Classifiers • Packets sorted into queues based on values in the DS (DiffServ) field • Traffic Conditioning Policies • Metering, Marking, Shaping and Policing based on DSCP and packet header data • Forwarding/Per Hop Behaviors • Expedited Forwarding and Assured Forwarding • Policy Managers • apply and communicate QoS policy

  15. Packet Classifiers • DiffServ Code Point (DSCP) • Maximum of 64 classes of service • Replaces IP TOS field • Packets sorted into queues based on DSCP values Source: QoS Forum

  16. Traffic Conditioning • Metering • Monitors traffic patterns against traffic profiles • Marking • DS field marks packet with specific values for each PHB (marked by edge routers) • Policing • Ingress routers drop or remark traffic that does not meet profiles and policies • Shaping • Egress routers control forwarding rate of packets and controls traffic flow to avoid congestion

  17. Per Hop Behaviors • Assured Forwarding (AF) • Similar to ATM nr-VBR QoS • Four AF classes with three codepoints each • AF classes not specifically defined regarding performance or priority between classes • Non-conforming traffic marked at the edge • RED queuing most often used. • Better then Best Effort Delivery • Gold, Silver, Bronze services • Expedited Forwarding • Guaranteed delay and jitter (similar to ATM CBR) • Provides a Virtual Leased Line service • Non-conforming policed on ingress and shaped on egress of Diffserv domain • Manual provisioning or signaling protocols required for quantitative guarantees. • Typically implemented with strict priority queuing

  18. DiffServ Code Points for Expedited Forwarding and Assured Forwarding Assured Class 1 Class 2 Class 3 Class 4 Class 5 Forwarding Low Drop 001010 (AF11) 010010 (AF21) 011010 (AF31) 100010 (AF41) Precedence Medium Drop 001100 (AF12) 010100 (AF22) 011100 (AF32) 100100 (AF42) Precedence High Drop 001110 (AF13) 010110 (AF23) 011110 (AF33) 100110 (AF43) Precedence Expedited 101110 Forwarding

  19. IEEE 802.1p • Traffic-handling mechanism for supporting QoS in LANs • Allows a classification/prioritization of differentiated services analogous to DiffServ • Operates at layer 2 (MAC) layer on a switched Ethernet network • Defines a field in the layer-2 header of “802” packets that can carry one of eight priority values

  20. IEEE 802.1p • Scope of 802.1p priority mark is limited to the LAN. Once packets are carried off the LAN, through a layer-3 device, the 802.1p priority is removed. • 802.1p often defined with 802.1q • Together, define various VLAN (virtual LAN) fields, as well as a priority field • Implemented in hardware (switches and routers)

  21. Multi Protocol Label Switching (MPLS) • More scalable mechanism for IP over ATM than classical overlay model • Edge routers can peer with nearby MPLS nodes • Avoids N2 scaling issues with ATM meshed networks • Traffic Engineering - using explicit routes and constraint-based routing for better load balancing. • As a tunneling mechanism to interconnect intra-VPN sites

  22. MPLS Network LSPs provide transport for • MPLS VPNs • Traffic Engineered Explicit Routes • DiffServ Aggregates

  23. QoS Implementation Status

  24. Significant Barriers to Implementing QoS

  25. QoS Implementation Issues • Inter-domain and Inter-Service Provider interoperability • Vendor interoperability • Limiting RSVP implementation in the core • Use RSVP to signal QoS to DiffServ and MPLS network cores • QoS support in applications • Monitoring and measuring QoS • Billing, accounting, pricing • Security and authentication • Policy management

  26. Biggest Challenge to Implementing QoS

  27. The Bottom Line • For Internet and WANs, DiffServ and MPLS top candidates for aggregated traffic flows and QoS • DiffServ from the edge through the core, or • DiffServ at the edge, MPLS at the core • RSVP for signaling

  28. The Bottom Line • For LANs and enterprise networks, 802.1p is top edge QoS mechanism using RSVP for signaling • Microsoft supports RSVP in Windows 2000 • Microsoft APIs for application based QoS development

  29. The Bottom Line • Where do you start? • Planning • Match QoS Mechanism to Applications, Services, Desired Traffic Types, and SLAs • Determine needed management and accounting platforms for measuring performance and usage • Design • Determine required hardware and software features, policy manager platforms, and policies, perform proof of concept • Implement • Deploy QoS mechanisms and associated services • Operate!

  30. Lucent Worldwide Services Professional Services • Service Provider Solutions • Business consulting • Custom on-premises solutions • Network engineering & design deployment • Network operations & management • Program management • Enterprise Consulting Solutions • Business consulting • Network management consulting • Microsoft technologies consulting • Performance engineering • Security solutions • Voice/Data convergence

  31. Question and Answer 12/20/201931

  32. Thank You • Feedback survey • Tell us what you think about this seminar www.lucentnps.com/seminars/thanks.asp • Upcoming seminars • Performance Management and Engineering, December 13th • For more information • E-mail seminars@ins.com • Call 1-888-767-2988

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