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Sidevõrgud IRT 0020

loeng 7 30. okt. 2006

Avo Ots

telekommunikatsiooni õppetoolraadio- ja sidetehnika instituut

avots@lr.ttu.ee

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Market

End-Users

Content and Service Providers

Service operators/Telecommunications Networking Solutions

Physical Telecommunication Network

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QoS• Pakettvõrkudes liikluse korralduse (traffic

engineering) mõiste “garanteeritud teenuse kvaliteet” (QoS, Quality of Service) tähendab tõenäosuslikku hinnangut, et sidevõrk jälgib liikluslepet.

• Paljudel juhtudel kasutatakse QoS tõenäosusena, et pakett läbib võrku saatjast vastuvõtjani oma ettemääratud ajavahemiku jooksul.

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Teenusekvaliteedi aspektidQoS – Quality of Service

ITU-T E.800 Recommendation

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Teenusekvaliteedi aspektid (2)

Teenuse Kättesaadavus

(Accessibility)

TeenusePüsivus

(Retainability)

TeenuseTerviklikus

(Integrity)

QoS

QoS parameetrid QoS parameetrid QoS parameetrid

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QoS rules

• QoS doesn't create bandwidth --it just determines who will get poor service at congestion points.

• The most important QoS question is: how many "busy" signals constitute success for your network?

• Given a busy signal, users will want to proceed anyway.• Network Managers will not trust end systems.• Biggest need is on WAN links, where it’s hardest to do!

(scaling, settlements, signalling interoperability).

• Multiplexing priorities on a channel improves efficiency at the cost of certainty.

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Link Scheduling: FIFO• First-in first-out scheduling

– Simple to implement

– But, restrictive in providing guarantees

• Example: two kinds of traffic– Video conferencing needs high bandwidth and low

delay• E.g., 1 Mbps and 100 msec delay

– E-mail transfers are not that sensitive about delay

• Cannot admit much e-mail traffic– Since it will interfere with the video conference traffic

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Link Scheduling: Strict Priority• Strict priority

– Multiple levels of priority– Always transmit high-priority traffic, when present– .. and force the lower priority traffic to wait

• Isolation for the high-priority traffic– Almost like it has a dedicated link– Except for the (small) delay for packet transmission

• High-priority packet arrives during transmission of low-priority

• Router completes sending the low-priority traffic first

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Link Scheduling: Weighted Fairness

• Limitations of strict priority– Lower priority queues may starve for long periods

– … even if the high-priority traffic can afford to wait

• Weighted fair scheduling– Assign each queue a fraction of the link bandwidth

– Rotate across the queues on a small time scale

– Send extra traffic from one queue if others are idle

50% red, 25% blue, 25% green

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4-bitVersion

4-bitHeaderLength

8-bitType of Service

(TOS)

16-bitTotal Length (Bytes)

16-bit Identification3-bitFlags 13-bit Fragment Offset

8-bit Time to Live (TTL)

8-bitProtocol

16-bit Header Checksum

32-bit Source IP Address

32-bit Destination IP Address

Options (if any)

Payload

20-byteHeader

IP Packet Structure

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16-bit destination port number

32-bit sequence number

32-bit acknowledgement number

16-bit TCP checksum

Options (if any)

Payload

20-byteHeader

16-bit source port number

16-bit window size4-bit

headerlength

FIN

SYN

RST

PSH

ACK

URG

16-bit urgent pointer

TCP Header

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Teenusekvaliteedi aspektid (3)

• Iga teenuse jaoks oma nõuded

• QoS profiil

• Erinevad teenusekvaliteedi tasemed vastavalt nõuetele

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Näidsvõrgud• Coexistence of heterogeneous networks

– Home networks, WLAN, 2G/3G, Campus-wide, satellite, …

– The development of multimode handsets is a major challenge

– Currently discussed standards fall short– Tomorrow user’s will expect the technology structure to

“disappear” and be of no concern

• Network architecture designed by IST project Daidalos– Provide seamless services accessible anytime anywhere

across heterogeneous technologies– Enhanced Mobile IPv6 platform for mobility and QoS– Support for optimized mobility– Integration with QoS resource management

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Sensor Integration

Platform

Administrative Domain 2

t

Access Network 13

Service Provisioning Platform 1

Access Network 12

Access Network 11

Core Router

Core Router

Core Router

Access Router

Access Router

Mobile IP

Routing (Ad-hoc)

QoS Agent

Registration Agent

Metering

Accounting

Charging

Key Management

SIP User Agent

SD&C Agent

Security Support

(Content Adaptation)

AnQoS BrokerMMSP Paging Agent

PBNMSA4CCnQoS BrokerHA

KDC CMSMMSPP

Edge Router

QoS Manager

Monitoring

Accounting

Adv. Router Mech,

Metering

QoS Manager

Ntw Monitor & Meter

Fast Handover

Accounting

Authorization

Adv. Router Mech.

QoS Manager

Monitoring

Accounting

Adv. Router Mech,

Metering

Authorization

Key Interconnection

(3P)SP Applications/Content

Service Platform 1

Fe

de

ratio

n/S

LA

Bridge Mesh and/or Hierarchical PKI

Service Composer

AccessPoint

Access Router

AccessPoint

AccessPoint

Currently used link

Candidate links

Mobilerouter

DPA

Mobile Network

Service Composer

MANET

Service Register

GPSlocation

Temperature

Health+Body

Sensor

InertiaCube

SecuritySensor

NoiseLevel

LightingSituation

ProximitySensor

SoftwareSensors

Activity(phone/mouse)

Lighting

GPSlocation

Temperature

Health+Body

Sensor

InertiaCube

SecuritySensor

NoiseLevel

LightingSituation

ProximitySensor

SoftwareSensors

Activity(phone/mouse)

Lighting

Location

Location

CAN

PerSP

PerSP

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Mobile Terminal

IAL

DVB-T MBMSTD-CDMA

WLAN WiMAX

QoSAL

UDLR

QoSCMTC

IISUserGUI

CARD FHO

IPv6++/MIPv6/Multicast

Technologies

TerminalIntelligence

QoS

Handover

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Access Router / Access Point

DVB-T MBMSTD-CDMA

WLAN WiMAX

QoSAL

UDLR

QoSMCARD PA

Technologies

TerminalIntelligence

QoS

NetworkIntelligenceAM

MM

FHO CT D&M

Handover

IPv6++/

MIPv6/PIM

ENC

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Handover

• Mobile Initiated Handover

• Network Initiated Handover

Triggered

• At startup

• Upon losing signal

Accounts for

• user preferences

• candidate APs load (QoS)

• signal strengths

Triggered by

• Overloaded AP (QoS)

• losing signal

Accounts for

• signal strengths of MTs

• APs load (QoS)

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Wi-Fi Alliance Roadmap[Amer Hassan, Microsoft, jaanuar 2005]

Baseline

Security

QoS

Applications

Q1 Q2 Q4Q32005

802.11e

WMMScheduled Access

Public Access CEPhase2

2004

Extended EAP

2006

802.11h+d

Simple Config

Voice/Wi-FiWCC

802.11j 802.11k

CEPhase1

WMM Power Save

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QoS vajadus• QoS vajadus esmases tähenduses tuleneb

video ja suure edastuskiirusega (mobiilsetest) andmesessioonidest

• Lõplikult kavatsetakse realiseerida standardina IEEE 802.11n, vahevariant realiseeriti standardina IEEE 802.11e, mida toetab Proximi AP-4000.

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Roadmap – WLAN