Quality of Service in IP Networks Presented by: John Rick Sharing the Knowledge Behind the Network Lucent Worldwide Services Knowledge Seminars

10/17/ Background s Lucent Worldwide Services is a provider of communications consulting, intelligent maintenance, and management solutions for next generation networks s Seminar objectives l Present the major factors driving QoS l Highlight current QoS technologies and techniques l Provide insight into the future direction of QoS for IP networks

10/17/ QoS Research s Web-based industry survey conducted September 2000 s 108 respondents s Represent a cross-section of end-user organizations and network solutions providers s Survey report available at

10/17/ 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

10/17/ Importance of Implementing/ Improving QoS

10/17/ The IP Network Problem s Congestion continues to plague the Internet Traffic expands = or > bandwidth ”Best-effort" performance dictated by the very design of the Internet Protocol (IP) s Mission critical applications, e.g., IP Telephony and ERP, require prioritization Service Level Agreements (SLAs) expected Customer expectations increase with bandwidth

10/17/ Why QoS s Over-provisioning bandwidth not cost effective in the long run Users will consume bandwidth as fast as produced s Need reliable data delivery Mission critical applications –ERP, SAP, Financial Market data High bandwidth, low latency applications –Video and audio streaming, video conferencing, voice s Provide value-added services with SLAs

10/17/ Contributing Factors to Importance of QoS

10/17/ QoS Technologies s Reservation Allocates resources on a per-flow basis Flows include information such as transport protocol, source address & port, destination address and port –Intserv/RSVP s Prioritization Traffic flows are aggregated and categorized by "class of service” –DiffServ and IEEE 802.1p

10/17/ Integrated Services s Defined in RFCs 2205, s 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

10/17/ RSVP s Signaling protocol that can operate in "native mode" or "encapsulated mode" within a UDP header s Operates in tandem with either a TCP or UDP "flow" to reserve resources among RSVP-enabled routers s Also being used to signal QoS into DiffServ and MPLS networks

10/17/ RSVP Request

10/17/ Differentiated Services (DiffServ) s Defined in RFCs 2474, 2475 s 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

10/17/ Building Blocks of DiffServ s Packet Classifiers Packets sorted into queues based on values in the DS (DiffServ) field s Traffic Conditioning Policies Metering, Marking, Shaping and Policing based on DSCP and packet header data s Forwarding/Per Hop Behaviors Expedited Forwarding and Assured Forwarding s Policy Managers apply and communicate QoS policy

10/17/ Packet Classifiers s 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

10/17/ Traffic Conditioning s Metering Monitors traffic patterns against traffic profiles s Marking DS field marks packet with specific values for each PHB (marked by edge routers) s Policing Ingress routers drop or remark traffic that does not meet profiles and policies s Shaping Egress routers control forwarding rate of packets and controls traffic flow to avoid congestion

10/17/ Per Hop Behaviors s 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 s 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

10/17/ DiffServ Code Points for Expedited Forwarding and Assured Forwarding Assured Forwarding Class 1Class 2Class 3Class 4Class 5 Low Drop Precedence (AF11) (AF21) (AF31) (AF41) Medium Drop Precedence (AF12) (AF22) (AF32) (AF42) High Drop Precedence (AF13) (AF23) (AF33) (AF43) Expedited Forwarding

10/17/ IEEE 802.1p s Traffic-handling mechanism for supporting QoS in LANs s Allows a classification/prioritization of differentiated services analogous to DiffServ s 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

10/17/ IEEE 802.1p s 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. s 802.1p often defined with 802.1q Together, define various VLAN (virtual LAN) fields, as well as a priority field s Implemented in hardware (switches and routers)

10/17/ Multi Protocol Label Switching (MPLS) s More scalable mechanism for IP over ATM than classical overlay model Edge routers can peer with nearby MPLS nodes Avoids N 2 scaling issues with ATM meshed networks s Traffic Engineering - using explicit routes and constraint-based routing for better load balancing. s As a tunneling mechanism to interconnect intra-VPN sites

10/17/ MPLS Network LSPs provide transport for MPLS VPNs Traffic Engineered Explicit Routes DiffServ Aggregates

10/17/ QoS Implementation Status

10/17/ Significant Barriers to Implementing QoS

10/17/ QoS Implementation Issues s Inter-domain and Inter-Service Provider interoperability s Vendor interoperability s Limiting RSVP implementation in the core s Use RSVP to signal QoS to DiffServ and MPLS network cores s QoS support in applications s Monitoring and measuring QoS s Billing, accounting, pricing s Security and authentication s Policy management

10/17/ Biggest Challenge to Implementing QoS

10/17/ sFor Internet and WANs, DiffServ and MPLS top candidates for aggregated traffic flows and QoS l DiffServ from the edge through the core, or l DiffServ at the edge, MPLS at the core l RSVP for signaling The Bottom Line

10/17/ sFor LANs and enterprise networks, 802.1p is top edge QoS mechanism using RSVP for signaling l Microsoft supports RSVP in Windows 2000 l Microsoft APIs for application based QoS development The Bottom Line

10/17/ sWhere do you start? l Planning n Match QoS Mechanism to Applications, Services, Desired Traffic Types, and SLAs n Determine needed management and accounting platforms for measuring performance and usage l Design n Determine required hardware and software features, policy manager platforms, and policies, perform proof of concept l Implement n Deploy QoS mechanisms and associated services l Operate! The Bottom Line

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10/17/ Question and Answer 10/17/

10/17/ Thank You s Feedback survey Tell us what you think about this seminar s Upcoming seminars Performance Management and Engineering, December 13th s For more information Call