1. Technical Presentation Series: QoS for MultiService IP Networks Quality of Service for MultiService IP Networks 8th March 2000 Quality of Service for MultiService IP Networks 8th March 2000 John A. Clark - Technical Account Manager

2. Technical Presentation Series: QoS for MultiService IP Networks - Page 2 Agenda Overview of Enterprise Quality of Service The Differentiated Services Model DiffServ Traffic Classification Mapping DiffServ to/from Link Layers RSVP for QoS Signaling Summary

3. Technical Presentation Series: QoS for MultiService IP Networks Enterprise Quality of Service … What is it & Why do we need it?

4. Technical Presentation Series: QoS for MultiService IP Networks - Page 4 What is driving the need for QoS? Increasing number of network users and applications New applications and traffic dynamics RT, Interactive traffic (VoIP) RT, non-Interactive traffic (Video on Demand, RealMedia) Non-RT, Interactive traffic (Web surfing) Non-RT, Mission Critical traffic (e-Commerce) Non-RT, non-Mission Critical traffic (everything else) Service Providers offering/pricing tiered levels of service Service differentiation in Intranets Ability to assign business priorities to traffic or users

5. Technical Presentation Series: QoS for MultiService IP Networks - Page 5 Traffic Classification Proposal Real-time, Delay Intolerant Absolute priority with no packet discard. Delay typically < 50ms Traffic CategoryRequired Treatment Inter-human communications (interactive), e.g., VoIP, Video conferencing Real-time, Delay Tolerant Guaranteed delivery with little to no packet discard Delay typically < 500ms Single-human communication (non- interactive), e.g., Steaming audio or video Application Examples Non-Real-time, Mission Critical Guaranteed delivery with minimal packet discard Delay typically < 5000ms Transaction processing, e.g., financial transactions, e-commerce Non-Real-time, Non-Mission Critical Best effort deliveryEmail, Web, FTP, SNMP, etc.

6. Technical Presentation Series: QoS for MultiService IP Networks - Page 6 PEN (Policy Enabled Networking) Strategy 3 Key Focus Areas QoS and Service Classification –Define Enterprise End-to-End QoS architecture –Standardize Service Classes used across Nortel products Packet Flow Classification –Define Queuing Mechanisms –Define Congestion Avoidance Mechanisms Policy Enablement –Define Centralized Policy Management requirements

7. Technical Presentation Series: QoS for MultiService IP Networks - Page 7 CoS QoS CoS WAN QoS/CoS: Whats the difference? For sake of discussion, let us define the following: CoS (Nodal): Behavioral treatment of traffic flows through a network node Traffic Prioritization and Discarding QoS (Network): Guaranteed level of traffic service performance across network CoS plus BW reservation/admission control mechanisms

8. Technical Presentation Series: QoS for MultiService IP Networks - Page 8 Simple Message: QoS achieved using CoS Mechanisms QoS Vision QoS over LANs Achieved using simple CoS mechanisms QoS over WANs Today: Requires BW reservation/admission control mechanisms Future: Will only need simple CoS mechanisms Vision will be achieved by implementing: Best CoS and congestion avoidance mechanisms Consistent treatment of CoS across all products Robust Policy Management solution

9. Technical Presentation Series: QoS for MultiService IP Networks Differentiated Services Model … The industry direction

10. Technical Presentation Series: QoS for MultiService IP Networks - Page 10 Differential Services (DiffServ) Model End-to-End Architecture defined by RFC 2475 Defines CoS on a Per Hop basis Relies on congestion avoidance mechanisms Requires all network nodes to comply to be effective Open Loop system No feedback from network to determine if there is congestion DiffServ Domain Set of DiffServ nodes with common service provisioning policy Policy Manager provides the policy

11. Technical Presentation Series: QoS for MultiService IP Networks - Page 11 DiffServ Domain DiffServ Domain across Campus LAN Ingress or Egress Nodes (Network Edge) L2 Switch L3 Switch Interior LAN Nodes (Network Core)

12. Technical Presentation Series: QoS for MultiService IP Networks - Page 12 Packet Treatment by DS Edge Nodes Policing Scheduling Marking DSCP Shaping Filtering based on: S/D IP Address, TCP/UDP Port, Protocol ID, DS Field (ToS) Policing Does the flow conform to policy? Marking Mark/Re-mark DS Code Point based on policy Congestion Management Drop Precedence Avoidance: RED or WRED Shaping Improves efficiency and conformance to policy Scheduling Ensures queues get serviced according to priorities

13. Technical Presentation Series: QoS for MultiService IP Networks - Page 13 Shaping Scheduling Packet Treatment by DS Core Nodes Policing Marking DSCP Shaping Congestion Management Drop Precedence Avoidance: RED or WRED Shaping Improves efficiency and conformance to policy Scheduling Ensures queues get serviced according to priorities Scheduling

14. Technical Presentation Series: QoS for MultiService IP Networks - Page 14 Per-Hop Behaviors (PHBs) PHBs are the packet-forwarding treatment that delivers the differentiated service to packets at network nodes Policing Possible remarking of DS Code Point (DSCP) Enqueuing treatment (e.g., drop preference) Shaping Scheduling IETF has defined the following DiffServ PHBs: Expedited Forwarding (EF) - RFC 2598 Assured Forwarding (AF) - RFC 2597 DEfault Forwarding (DE) - RFC 2474

15. Technical Presentation Series: QoS for MultiService IP Networks - Page 15 DS Field DS Field defined by RFC 2474 Supercedes existing definitions IPv4 ToS Field (RFC 791) IPv6 Traffic Class Octet (RFC 2460)

16. Technical Presentation Series: QoS for MultiService IP Networks DiffServ Traffic Classification

17. Technical Presentation Series: QoS for MultiService IP Networks - Page 17 Expedited Forwarding (EF) PHB - RFC 2598 Virtual leased line Substitute Service Police and drop on network ingress Modest buffering needed (no burst) Typically uses strict priority queuing Shape on egress to maintain contract with next DS Domain Network Engineering Requirements Egress rate must exceed ingress rate Traffic Engineering Guidelines For multiservice networks, EF Traffic is typically kept to a small fraction of total network traffic, e.g., 10% However, this is completely application-dependent EFDSCP = 101110

18. Technical Presentation Series: QoS for MultiService IP Networks - Page 18 Assured Forwarding (AF) PHB - RFC 2597 Lowest Latency Highest Latency Highest Discard Lowest Discard 4 AF Classes (priority classes) 3 Drop Precedences per AF class 6-bit value located in the DS Field

19. Technical Presentation Series: QoS for MultiService IP Networks - Page 19 Proposed Service Classification for Nortel EF PHB DE PHB AF PHBs Service Class names make configuration more intuitive DiffServ PHBs

20. Technical Presentation Series: QoS for MultiService IP Networks - Page 20 Congestion Avoidance Mechanisms Required for DiffServ architecture to work properly Drop Precedence AF PHB offers 3 levels of drop precedence for each AF class All DE PHB traffic is eligible to discard No EF PHB traffic is eligible to discard RED Required to break global synchronization of TCP/IP sessions Actively and randomly drops packets WRED/MRED variants allow weighting of different queues

21. Technical Presentation Series: QoS for MultiService IP Networks - Page 21 Traffic Scheduling Strict Priority Schedulers Assigns a fixed % of total BW to a queue Queue must be emptied prior to others being serviced Weighted Bandwidth Schedulers Lower priority queues borrow higher priority queue BW when available –Higher priority queues reclaim borrowed BW as needed Two Commonly used algorithms –Weighted Round Robin (WRR) –Weighted Fair Queuing (WFQ)

22. Technical Presentation Series: QoS for MultiService IP Networks - Page 22 Nodal Handling

23. Technical Presentation Series: QoS for MultiService IP Networks Mapping IP to/from Link Layers … preserving DiffServ behavior at Layer 2

24. Technical Presentation Series: QoS for MultiService IP Networks - Page 24 IP/Layer 2 Traffic Classification IP Filtering on: Source/Destination IP Address Source/Destination TCP/UDP Port number DSCP Protocol ID Ethernet 802.1p User Priorities 8 User Priorities Highest level queue serviced before next lower level queue ATM CBR, rt-VBR, nrt-VBR, ABR, UBR Single or Multiple Virtual Circuits Frame Relay CIR, EIR, DE Single or Multiple Virtual Circuits

25. Technical Presentation Series: QoS for MultiService IP Networks - Page 25 Ethernet 802.1p User Priorities 8 User Priorities (traffic classes) DiffServ PHB mapped to/from 802.1p User Priorities 6 bytes Dest MAC Source MAC 802.1q TAG 4 bytes Protocol Type 2 bytes Data 64-1500 bytes Tag Protocol Identifier Tag Control Info 81 - 00 Priority bits CFICFI VLAN ID

26. Technical Presentation Series: QoS for MultiService IP Networks - Page 26 DSCP to 802.1p Mapping Example Standard, power-up default mapping Egress to non-Layer 3 aware L2 Switch Required because L2 switch cannot interpret DSCP

27. Technical Presentation Series: QoS for MultiService IP Networks - Page 27 DSCP to ATM CoS Mapping Example Sample, power-up default mapping ATM to DSCP mapping not required IP DSCP is preserved across ATM network

28. Technical Presentation Series: QoS for MultiService IP Networks - Page 28 DSCP to Frame Relay VC Mapping Example Frame Relay does not have any native CoS mechanisms Each VC is assigned the following for each flow Guaranteed BW (CIR) Burst BW (EIR) Discard Eligibility (DE)

29. Technical Presentation Series: QoS for MultiService IP Networks RSVP for QoS Signaling … a new use for RSVP

30. Technical Presentation Series: QoS for MultiService IP Networks - Page 30 New use for RSVP RSVP for DiffServ Used as a QoS signaling mechanism Application or appliance uses RSVP to request: –Bandwidth –Prioritization –Authentication –Authorization Request made to edge device in DiffServ domain Edge device or Policy Server admit or reject request Driven by Microsofts inclusion of RSVP enabling technology in Windows 2000

31. Technical Presentation Series: QoS for MultiService IP Networks - Page 31 L2 Switch Sets DSCP and 802.1p User Priority based on OPS policy setting L3 Switch Sets DSCP or 802.1p User Priority based on OPS policy setting Etherset Sets DSCP or 802.1p User Priority PBX VoIP Sets DSCP Upstream devices configured to respect DSCP Supports H.323 Router (VoIP Media Gateway) Sets DSCP based on OPS policy setting State is maintained between OPS and router IP Classification w/o RSVP QoS Signaling

32. Technical Presentation Series: QoS for MultiService IP Networks - Page 32 IP Classification with RSVP QoS signaling Client PC QoS signaled via RSVP Win2000 app. sets DSCP NIC sets 802.1p user priority L2 Switch Detects RSVP packet and forwards to OPS OPS sends DSCP via COPS Maps DSCP to 802.1 user priority L3 Switch Detects RSVP packet and forwards to OPS OPS determines DSCP and sends via COPS Etherset Sets DSCP or 802.1p User Priority PBX VoIP Sets DSCP Upstream devices configured to respect DSCP Supports H.323 Router VoIP Media Gateway Detects RSVP packet Requests policy from OPS based on RSVP message Sets DSCP based on Optivity Policy Server (OPS) policy setting State is maintained between OPS and router

33. Technical Presentation Series: QoS for MultiService IP Networks - Page 33 Summary DiffServ is the predominant IP QoS Architecture IP QoS is in the early stages of standardization Good traffic management required to make all this work Policy Enablement simplifies and automates network administration

34. Technical Presentation Series: QoS for MultiService IP Networks Thank you Questions ? John A. Clark - Technical Account Manager