Technical QoS, applications: IP, Technical QoS, applications: IP, UMTSUMTS

Helsinki University of TechnologyS-72.2530 Acceptability and Quality of Service

2.12.2008Marko Rosberg

Why QoS is needed in IP level?Why QoS is needed in IP level?

QoS-demanding IP aplicationsQoS-demanding IP aplications

- Voice over IP (VoIP)- Voice over IP (VoIP)

- Internet Telephony- Internet Telephony

- tele conferencing- tele conferencing

- virtual private networks (VPN)- virtual private networks (VPN)

- e-commerce- e-commerce

ChallengesChallenges

- Network load may vary much- Network load may vary much- Over-provisioning in wired connections- Over-provisioning in wired connections

- IP is connectionless protocol- IP is connectionless protocol

- Very different kinds of requirements from - Very different kinds of requirements from different applications different applications (e.g. VoIP datarates are quite small (e.g. VoIP datarates are quite small but latency should be less than 100ms)but latency should be less than 100ms)

- Requires changes to Internet backbones- Requires changes to Internet backbones

- Different kind of technologies used- Different kind of technologies used- 3G, WLAN, ADSL, Optical fibers- 3G, WLAN, ADSL, Optical fibers

Methods for adding QoS controlMethods for adding QoS control

- Traffic modeling- Traffic modeling

- Admission Control- Admission Control

- Shaping and Policing- Shaping and Policing

- Signaling and Resource Management- Signaling and Resource Management

- Queuing and Scheduling- Queuing and Scheduling

- Cognestion control and Queue Management- Cognestion control and Queue Management

- QoS Routing- QoS Routing

- QoS Policy Management- QoS Policy Management

- Pricing- Pricing

How is it made in IPv4?How is it made in IPv4?

- IP V4 header includes Type of Service (ToS) - IP V4 header includes Type of Service (ToS) fieldfield

- Defined 1981 in RFC791- Defined 1981 in RFC791

- Length 8bit- Length 8bit- The major choice is a three way tradeoff between low-

delay,high-reliability, and high-throughput

- The use of the Delay, Throughput, and Reliability indications may increase the cost

How is it made in IPv4? cont.How is it made in IPv4? cont.

- ToS field consists of the following bits- ToS field consists of the following bitsBits 0-2:Bits 0-2:Precedence.Precedence.

Bit 3:Bit 3: 0 = Normal Delay, 1 = Low Delay.0 = Normal Delay, 1 = Low Delay.

Bits 4:Bits 4: 0 = Normal Throughput, 1 = High Throughput.0 = Normal Throughput, 1 = High Throughput.

Bits 5:Bits 5: 0 = Normal Relibility, 1 = High Reliability.0 = Normal Relibility, 1 = High Reliability.

Bit 6-7:Bit 6-7: Reserved for Future Use.Reserved for Future Use.PrecedencePrecedence

111 - Network Control111 - Network Control110 - Internetwork Control110 - Internetwork Control101 - CRITIC/ECP101 - CRITIC/ECP100 - Flash Override100 - Flash Override011 - Flash011 - Flash010 - Immediate010 - Immediate001 - Priority001 - Priority000 - Routine000 - Routine

- The type of service is used to specify the treatment of the datagram during its transmission through the internet system.

IPv4 in practiceIPv4 in practice

- ToS field has not been widely implemented- ToS field has not been widely implemented

- Much research focused on how these bits could - Much research focused on how these bits could be usedbe used

- Bits have been redefined, most recently through - Bits have been redefined, most recently through DiffServ working groupDiffServ working group

- ToS field is now used for DiffServ and ECN- ToS field is now used for DiffServ and ECN

What is DiffServ ?What is DiffServ ?

- DiffServ stands for Differentiated Services- DiffServ stands for Differentiated Services

- Defined 1998 in RFC 2475- Defined 1998 in RFC 2475

- It operates on principle of traffic classification- It operates on principle of traffic classification

- Each router is configured to differentiate traffic - Each router is configured to differentiate traffic based on its classbased on its class

- It can be used to provide low latency traffic for - It can be used to provide low latency traffic for voice and video services while providing best-voice and video services while providing best-effort traffic for non critical trafficeffort traffic for non critical traffic

What is ECN?What is ECN?

- ECN stands for Explicit Congestion Notification- ECN stands for Explicit Congestion Notification

- Defined 2001 in RFC 3168- Defined 2001 in RFC 3168

- Uses DiffServ field- Uses DiffServ field

- allows end-to-end notification of network - allows end-to-end notification of network congestion without dropping packetscongestion without dropping packets

- It's an optional feature (only used when both - It's an optional feature (only used when both endpoints signal that they want to use it)endpoints signal that they want to use it)

- only effective in combination with an Active - only effective in combination with an Active Queue Management (AQM) policyQueue Management (AQM) policy

QoS control in IPv6QoS control in IPv6

- Header includes 20 bits long flow label for QoS - Header includes 20 bits long flow label for QoS managementmanagement

- Basics of Flow Label is specified in RFC 3697- Basics of Flow Label is specified in RFC 3697- Published in 2004- Published in 2004

- The specific properties and utility of this header field are not well - The specific properties and utility of this header field are not well defined at presentdefined at present

- Enables classification of packets belonging to a - Enables classification of packets belonging to a specific flowspecific flow

- Routers priorizes IP packets based on flow type- Routers priorizes IP packets based on flow type

QoS in UMTSQoS in UMTS

- W-CDMA (UMTS) (Wideband Code Division - W-CDMA (UMTS) (Wideband Code Division Multiple Access) is a type of 3G cellular networkMultiple Access) is a type of 3G cellular network

- QoS control used in different levels of OSI-- QoS control used in different levels of OSI-ModelModel

- Optimum use of spectrum is important- Optimum use of spectrum is important

- Overprovisioning is very expensive alternative- Overprovisioning is very expensive alternative

QoS in UMTS cont.QoS in UMTS cont.

Radio network QoS/Core network interface- Connection oriented- Differentiated Services can be used at IP layer- ATM-based transmission

Core network QoS- Differentiated Services proposed

PDP context approachUMTS-specific QoS parametersFlexible renegotiation of QoS- Flow specifications at GGSN- UMTS-specific QoS parameters

Radio QoS support- Covers all traffic types- Dedicated vs. shared channels- Soft handover- Real-time handover

QoS in UMTS cont.QoS in UMTS cont.

- Most of the QoS control is done at the bearer - Most of the QoS control is done at the bearer levellevel

- Used methods:- Used methods: Admission controlAdmission control Bearer service managerBearer service manager Resource managerResource manager Traffic conditionerTraffic conditioner Packet classifierPacket classifier

Admission control & Bearer service Admission control & Bearer service managermanager

Admission ControlAdmission Control

- maintains information about the allocated and free - maintains information about the allocated and free resourcesresources

- allocates and frees resources based on QoS parameter - allocates and frees resources based on QoS parameter valuesvalues

Bearer service managerBearer service manager

- co-ordinates signal plane to establish, modify and maintain - co-ordinates signal plane to establish, modify and maintain the particular bearer servicethe particular bearer service

- consults admission control and translates QoS attributes for - consults admission control and translates QoS attributes for local bearerlocal bearer

Resource Manager & Traffic Resource Manager & Traffic ControllerController

Resource ManagerResource Manager

- Responsible for managing access to resources in - Responsible for managing access to resources in accordance with particular bearer serviceaccordance with particular bearer service

- Uses QoS parameters for scheduling, bandwith - Uses QoS parameters for scheduling, bandwith management and power controlmanagement and power control

Traffic ConditionerTraffic Conditioner

- Traffic shaping and policing- Traffic shaping and policing

- Ensures uplink in MS* and downlink in GGSN**- Ensures uplink in MS* and downlink in GGSN**

- The result TC is a packet with appropiate QoS indication - The result TC is a packet with appropiate QoS indication e.g. IP packete.g. IP packet

*MS = Mobile Station **GGSN = Gateway GPRS Support Node

Packet ClassifierPacket Classifier

- Classifies packets to bearer service based on - Classifies packets to bearer service based on QoS attributesQoS attributes

- Four different traffic classes- Four different traffic classes

- Conversational class- Conversational classreal time traffic e.g. Video telephonyreal time traffic e.g. Video telephony

- Streaming class- Streaming classmedia streaming traffic e.g. Video downloadmedia streaming traffic e.g. Video download

- Interactive class- Interactive classservices reguiring assure throughput e.g. Interactive webservices reguiring assure throughput e.g. Interactive web

- Background class services- Background class servicesbest-effort data e.g. Downloading files or emailbest-effort data e.g. Downloading files or email

CriticsCritics

- There are many different ways for adding QoS - There are many different ways for adding QoS to IPto IP

It's allmost impossible to have connection on the It's allmost impossible to have connection on the Internet, where every node between the endpoints Internet, where every node between the endpoints supports QoS method that you are using.supports QoS method that you are using.

- There have been mutch articles of unsatisfied - There have been mutch articles of unsatisfied customers using UMTS (what went wrong?)customers using UMTS (what went wrong?)

Thank you for listening!!Thank you for listening!!

Sources:Sources:

1) Wikipedia IP, 1) Wikipedia IP, http://en.wikipedia.org/wiki/Ip

2) Wikipedia UMTS, 2) Wikipedia UMTS, http://en.wikipedia.org/wiki/Umts

3) Rajeev Koodli and Mikko Puuskari, Nokia Research Center, Supporting 3) Rajeev Koodli and Mikko Puuskari, Nokia Research Center, Supporting Packet-Data QoS in Next-Generation Cellular Networks, IEEE 2001Packet-Data QoS in Next-Generation Cellular Networks, IEEE 2001

4) JOHN SOLDATOS et.al. , ON THE BUILDING BLOCKS OF QUALITY OF 4) JOHN SOLDATOS et.al. , ON THE BUILDING BLOCKS OF QUALITY OF SERVICE IN HETEROGENEOUS IP NETWORKS, IEEE 2005, SERVICE IN HETEROGENEOUS IP NETWORKS, IEEE 2005, http://www.comsoc.org/pubs/surveys

5) RFC791, Internet Protocol, 1981, 5) RFC791, Internet Protocol, 1981, http://tools.ietf.org/html/rfc791

6) RFC3697 - IPv6 Flow Label Specification, 2004, 6) RFC3697 - IPv6 Flow Label Specification, 2004, http://www.faqs.org/rfcs/rfc3697.html