Quality of Service in IP

Networks

Presented by:

John Railsback jrailsback@lucent.com

Rick Blum rickblum@lucent.com

Sharing the Knowledge Behind the Network

Lucent Worldwide Services Knowledge Seminars

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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

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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

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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

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Importance of Implementing/ Improving QoS

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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

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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

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Contributing Factors to Importance of QoS

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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

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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

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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

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RSVP Request

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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

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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

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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

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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

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Per Hop Behaviors

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

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

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DiffServ Code Points for Expedited Forwarding and Assured Forwarding

AssuredForwarding

Class 1 Class 2 Class 3 Class 4 Class 5

Low DropPrecedence

001010 (AF11) 010010 (AF21) 011010 (AF31) 100010 (AF41)

Medium DropPrecedence

001100 (AF12) 010100 (AF22) 011100 (AF32) 100100 (AF42)

High DropPrecedence

001110 (AF13) 010110 (AF23) 011110 (AF33) 100110 (AF43)

ExpeditedForwarding

101110

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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

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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)

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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

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MPLS Network

LSPs provide transport for

• MPLS VPNs

• Traffic Engineered Explicit Routes

• DiffServ Aggregates

CloudIGP Domain

LSR

Legend

EdgeLSR

LSR

LSP

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QoS Implementation Status

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Significant Barriers to Implementing QoS

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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

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Biggest Challenge to Implementing QoS

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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

The Bottom Line

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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

The Bottom Line

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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!

The Bottom Line

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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

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Question and Answer

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Thank You

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Upcoming seminars• Performance Management and Engineering,

December 13th

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• Call 1-888-767-2988