The document outlines a cooperation agreement between Proydesa Foundation and SLS Latam to enhance technology-focused education in alignment with Cisco Systems' efforts. It covers Quality of Service (QoS) in converged networks, detailing traffic classification, requirements for voice and video, potential quality issues, and QoS mechanisms. Additionally, it discusses various QoS implementation methods, including IntServ and DiffServ models, and offers insights on how to ensure bandwidth efficiency and prioritize time-sensitive traffic.

2. Convenio Marco de Cooperación y Asistencia Técnica

3. ..\Presentacion\SLS\barra.jpg Fundación Proydesa y la filial Argentina de SLS LATAM Tienen el agrado de comunicar la formalización de un Convenio Marco de Cooperación y Asistencia Técnica con el objeto de investigar, desarrollar y promover la formación en y con tecnología, ingresando decididamente como actores protagónicos en la Educación del Siglo XXI y acompañando en forma coordinada el esfuerzo que diariamente realiza Cisco Systems por cambiar la forma en que nos comunicamos y educamos

4. Using the Medium

5. Introducing QoS Understanding the Need for QoS

6. QoS Defined

7. Before Converged Networks Traditional data traffic characteristics: Bursty data flow First-come, first-served access Mostly not time-sensitive – delays OK Brief outages are survivable

8. After Converged Networks Converged traffic characteristics: Constant small-packet voice flow competes with bursty data flow Critical traffic must get priority Voice and video are time-sensitive Brief outages not acceptable

9. Converged Networks: Quality Issues Telephone Call: “I cannot understand you; your voice is breaking up.” Teleconferencing: “The picture is very jerky. Voice not synchronized.” Brokerage House: “I needed that information two hours ago. Where is it?” Call Center: “Please hold while my screen refreshes.”

10. QoS Traffic Requirements: Data Different applications have different traffic characteristics. Different versions of the same application can have different traffic characteristics. Classify data into relative-priority model with no more than four to five classes: Mission-Critical Apps: Locally defined critical applications Transactional: Interactive traffic, preferred data service Best-Effort: Internet, e-mail, unspecified traffic Less-Than-Best-Effort (Scavenger): Napster, Kazaa, peer-to-peer applications

11. QoS Traffic Requirements: Voice Latency < 150 ms* Jitter < 30 ms* Loss < 1%* 17-106 kbps guaranteed priority bandwidth per call 150 bps (+ Layer 2 overhead) guaranteed bandwidth for voice-control traffic per call *one-way requirements – QoS Traffic Requirements: Voice

12. QoS Requirements: Videoconferencing Latency ≤ 150 ms* Jitter ≤ 30 ms* Loss ≤ 1%* Minimum priority bandwidth guarantee required is: Video stream + 20% For example, a 384 kbps stream would require 460 kbps of priority bandwidth *one-way requirements

13. Converged Networks: Quality Issues (Cont.) Lack of bandwidth: Multiple flows compete for a limited amount of bandwidth. End-to-end delay (fixed and variable): Packets have to traverse many network devices and links that add up to the overall delay. Variation of delay (jitter): Sometimes there is a lot of other traffic, which results in more delay. Packet loss: Packets may have to be dropped when a link is congested.

14. Best-Effort: No QoS is applied to packets. IntServ: Applications signal to the network that they require special QoS. DiffServ: The network recognizes classes that require special QoS.

15. Best-Effort Model It will get there when it gets there. Internet initially based on a best-effort packet delivery service The default mode for all traffic No differentiation between types of traffic Like using standard mail

16. Best-Effort Model (Cont.) Benefits: Highly scalable No special mechanisms required Drawbacks: No service guarantees No service differentiation

17. IntServ Model Some applications have special bandwidth or delay requirements or both IntServ introduced to guarantee a predictable behavior of the network for these applications Guaranteed delivery: no other traffic can use reserved bandwidth Like having your own private courier plane It will be there by 10:30 a.m.

18. IntServ Model (Cont.) Provides multiple service levels Requests specific kind of service from the network before sending data Uses RSVP to reserve network resources Uses intelligent queuing mechanisms End to end

19. RSVP QoS services Guaranteed-rate service Controlled-load service RSVP provides policy to QoS mechanisms IntServ Model (Cont.)

20. IntServ Model (Cont.) Benefits: Explicit resource admission control (end to end) Per-request policy admission control (authorization object, policy object) Signaling of dynamic port numbers (for example, H.323) Drawbacks: Continuous signaling because of stateful architecture Flow-based approach not scalable to large implementations such as the public Internet (can be made more scalable when combined with elements of the DiffServ model)

21. DiffServ Model Network traffic identified by class Network QoS policy enforces differentiated treatment of traffic classes You choose level of service for each traffic class Like using a package delivery service Do you want overnight delivery? Do you want two-day air delivery? Do you want three- to seven-day ground delivery?

22. Overview R1 R2

23. QoS for Converged Networks

24. Step 1: Identify Traffic and Its Requirements Network audit Identify traffic on the network Business audit Determine how each type of traffic is important for business Service levels required Determine required response time

25. Step 2: Divide Traffic into Classes

26. Classification Classification is the identifying and splitting of traffic into different classes. Traffic can be classed by various means, including the DSCP. Modular QoS CLI allows classification to be implemented separately from policy.

27. Marking Marking, also known as coloring, marks each packet as a member of a network class so that the packet class can be quickly recognized throughout the rest of the network.

28. Differentiated Services Model The Differentiated Services model describes services associated with traffic classes. Complex traffic classification and conditioning is performed at the network edge, resulting in a per-packet DSCP . No per-flow state in the core. The core only performs simple “per-hop behaviors” on traffic aggregates. The goal is scalability.

29. DSCP Encoding DiffServ field: The IP version 4 header ToS octet or the IPv6 traffic class octet, when interpreted in conformance with the definition given in RFC 2474 DSCP: The first six bits of the DiffServ field, used to select a PHB (forwarding and queuing method)

30. DiffServ Model (Cont.) Benefits: Highly scalable Many levels of quality possible Drawbacks: No absolute service guarantee Complex mechanisms

31. Break - 10 mins

32. QoS for Converged Networks

33. QoS Mechanisms Classification: Each class-oriented QoS mechanism has to support some type of classification. Marking: Used to mark packets based on classification, metering, or both. Congestion management: E ach interface must have a queuing mechanism to prioritize transmission of packets. Congestion avoidance: Used to drop packets early to avoid congestion later in the network. Policing and shaping: Used to enforce a rate limit based on the metering (excess traffic is either dropped, marked, or delayed). Link Efficiency: Used to improve bandwidth efficiency through compression, link fragmentation, and interleaving.

34. Classification Classification is the identifying and splitting of traffic into different classes. Traffic can be classed by various means, including the DSCP. Modular QoS CLI allows classification to be implemented separately from policy.

35. Marking Marking, also known as coloring, marks each packet as a member of a network class so that the packet class can be quickly recognized throughout the rest of the network.

36. Congestion Management Congestion management uses the marking on each packet to determine in which queue to place packets. Congestion management uses sophisticated queuing technologies, such as WFQ and LLQ, to ensure that time-sensitive packets such as voice are transmitted first.

37. Congestion Avoidance Congestion avoidance may randomly drop packets from selected queues when previously defined limits are reached. By dropping packets early, congestion avoidance helps prevent bottlenecks downstream in the network. Congestion avoidance technologies include random early detection and weighted random early detection.

38. Policing Policing drops or marks packets when a predefined limit is reached.

39. Shaping Shaping queues packets when a predefined limit is reached.

40. Compression Header compression can dramatically reduce the overhead associated with voice transport.

41. Link Fragmentation and Interleaving Without link fragmentation and interleaving, time-sensitive voice traffic can be delayed behind long, non-time-sensitive data packets. Link fragmentation breaks long data packets apart and interleaves time-sensitive packets so that the time-sensitive packets are not delayed.

42. Applying QoS to Input and Output Interfaces

43. Methods for Implementing QoS Policy CLI MQC AutoQoS VoIP (voice QoS) AutoQoS Enterprise (voice, video, and data QoS) QPM

44. Implementing QoS with CLI interface Multilink1 ip address 10.1.61.1 255.255.255.0 ip tcp header-compression iphc-format load-interval 30 custom-queue-list 1 ppp multilink ppp multilink fragment-delay 10 ppp multilink interleave multilink-group 1 ip rtp header-compression iphc-format ! Traditional method Nonmodular Cannot separate traffic classification from policy definitions Used to augment, fine-tune newer AutoQoS method

45. Implementing QoS with MQC A command syntax for configuring QoS policy Reduces configuration steps and time Configure policy, not “raw” per-interface commands Uniform CLI across major Cisco IOS platforms Uniform CLI structure for all QoS features Separates classification engine from the policy class-map VoIP-RTP match access-group 100 class-map VoIP-Control match access-group 101 ! policy-map QoS-Policy class VoIP-RTP priority 100 class VoIP-Control bandwidth 8 class class-default fair-queue ! interface serial 0/0 service-policy output QoS-Policy ! access-list 100 permit ip any any precedence 5 access-list 100 permit ip any any dscp ef access-list 101 permit tcp any host 10.1.10.20 range 2000 2002 access-list 101 permit tcp any host 10.1.10.20 range 11000 11999

46. Implementing QoS with AutoQoS [trust] option is used to trust DSCP marking AutoQoS VoIP supported both in the LAN and WAN environments AutoQoS Enterprise supported on WAN interfaces Routers can deploy Enterprise QoS policy treatment for voice, video, and data traffic Switches can deploy QoS policy treatments for voice by a single command

47. Comparing Methods for Implementing QoS