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Internet QoSInternet QoS

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What is QoS?

Delay, delay jitter, bandwidth, drop rate, etc. - .

-

.

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Application Layer QoS requirements

Transport Layer IntServ/DiffServ

MPLS

Link Layer

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Providing guaranteed service

Using RSVP signaling protocol to reserve resource alonge pa

Problem in scalability

PATH PATHSender ReceiverR R

PATH PATH

RESVESV

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Service classes

Guaranteed service

Required mechanisms

Admission control

Signalling (Resource reservation)

Packet scheduling

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Traffic characteristics Tspec

Average sending rate is not

3

)enough.

Using token bucket filter

Service requested Rspec2

Flow B

h(MBps

Controlled load service Guaranteed service specify

delay bound 1Flow A

andwidt

1 2 3 4

Time (seconds)

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Receiver-oriented

for multicasting support o -sa e

for robustness

-

PATH and RESV messages

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Classifying

associating each packet with the appropriate reservation ,

number

flow label field in IPv6

Scheduling FIFO is not enough

WFQ hard to implement

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Per-flow state

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A sca a e so ution propose y IETF to provi e service

differentiation in IP networks.

RFCs on the DiffServ

Definition of the DS Field in the IPv4 and IPv6 Headers (RFC 2474)

An Architecture for DiffServ (RFC 2475)

n xpe e orwar ng

Assured Forwarding PHB Group (RFC 2597)

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Overview of a DiffServ Netw orkOverview of a DiffServ Netw ork

HEdge Router- Core Router

M- Classifying

- Markin

-

- EF PHB

RRH

M

R

H

M

H

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a e rem um serv ce, rtua ease ne or rtua re

Guaranteeing low loss rate, low latency, low jitter and assured BW

through end-to-end path

Intended to send circuit replacement traffic across a DiffServ network

Mimic the behavior of a hard-wired circuit

-,

Suitable for IP telephony or video conferencing

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.. u es

Each node in the domain must implement the EF PHB.

Conditioning the aggregate so that its arrival rate at any node is always less .

Characteristics

The same as a wire

Delivered with a high degree of assurance and with almost no distortion ofthe interpacket timing

Arrival rate > Configured rate

Unconditionally discarded

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--

Edge Router

Priority Que.

SLA

EF packet

M

es -e or

RR

H

M

MR

H

H

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A CBR flow of size S packets being sourced at rate R.

Link bandwidth in the domain, B = nR.

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Potential Sources of QueueingPotential Sources of Queueing

DelayDelay on- pac e s

EF priority queueing -> the only delay experienced for waiting the finish of a

packet that are being sent at the time it arrived. - = -> >=

Another VW packet from the same customer

The incoming VW stream is strictly shaped to a rate R.

n er-pac e spac ng = .

No delay only of the link bandwidth > R

VW packets from other customer

Not s own at a rece ver on y t e n an w t > nR

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Providing better service

Service Level Agreement (SLA) specify the amount of

Packet marked IN/OUT

erent rop rate or pac et

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..

Edge Router

RED IN/OUT

SLA 1

M

eter ar erac ets

qOUT IN

RR

H

M

MR

H

H

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Providing a route that is most likely to be able to

A tool for Traffic Engineering

Helping DiffServ

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Forwarding scheme using fixed length header (label)

Between L2 and L3 Fast packet forwarding

LDP (Label Distribution Protocol) required to setup LSP

a e w tc e at

Working with QoS routing

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