Weighted Fair Queuing

Traffic Management: 11 ( )

22

.3 :1 - (CAC) 2- (Traffic policing and Traffic shaping)3- 4- 5- 6-

4 :1- (CAC) : .2- : .3- ( Congestion Control): .

5 : . :

1- : .

2- ( scheduling ): . .3- ( buffer management ): .

4- ( packet drop ): , .

6 :Planning and designNetwork statisticsConfiguration flexibilityNetwork management toolsConnection Admission Control

Routing

Call duration

Flow control (ABR)Memory and queue managementPolicing Scheduling and shapingCell timeNetwork EngineeringNetwork-Level ControlsNode-Level ControlsNon-real-timeModular approachto network design,dynamic configurationand management of Virtual Networks.Measurement-based CAC which is back-ward compatible.Encompasses both real-time connection control and non-real-time network management:An integrated view of traffic+resource+network management to dynamically adapt network to changes in traffic, services and applicationsMeasurement-based routing building on the Virtual Network concept Rate and fair-share schedulers with priorities. Simple FIFO structures also workable.7 _ : ( congesstion avoidance ) :Traffic shaping and policingPacket drop techniquesBandwidth management policies. The primary aim of these techniques _ : ( Reactive ) :TCP congestion control: window-basedABR rate-based congestion control in ATM networks8 :

1-

2- 9 . .

:

a _ aggregate

b Virtual Path ( VP) ATM LSP MPISc VC ATM10 (Logical Subnetwork) . ( Virtual Network) . overlay .

_ , .

_ ( VP LSP ) .. ATM MPLS LSP .

_ , (Flows) ( Sessions) . .

VP VP :1- End- to- end :

2-hop- by- hop :

3- Segment-by-Segment : . vp .13 VP B(bps) .

. 100% . . (peak rate) .

. .14 ( ) (B) . B . EGH . :B : ( )R : R* B2B Burst ( R ) CLR :CLR=F( B/R, B2B, )

B/R1>B/R2 : F(B/R1 , B2B, ) > F(B/R2, B2B, )15 :

1- : .

2- : CAC . .16 . : 1: complete sharing- . Round- Robin FIFO CAC . .

, . .

. , .17 2: Complete separation .

, .

.

.

18 3 work-conserving scheduling: . . 2 1 .19 4 Prioritized work-conserving scheduling (PWCS):- , .- Traffic Policing ._ .20 PWCS PWCS :

VBR: high-priority trafficABR: low-priority elastic traffic PWCS :N=(Bvbr* U ) / Cvbr Bvbr VBR Cvbr U , CLR=F( B/R, B2B, ) . R . Complete Partitioning: B=Bvbr PCWS: B =150e+6 B2B , PWCS 2 2 .22 work-conserving scheduling . . . Measurement-based . .

-2 :_ , , (VC ) (VP ) ( VN ) .

_ , .

_ .

_ , .

_ , Blocking . Blocking .25 CAC .CAC :1- .

2- . .

26Network Planning Network Planning . :_ _ _ - .27End-to-End PerformanceCalculationInternal Traffic Computationfacility

specificationsGOS & QoS specificationstraffic

between

nodesFinal designNodal LayoutCost profile /

parametersRouting

PolicyCAC

PolicyExternal Trafficlocations

and

capacitiesInternodal Topological DesignNetwork Planning Flowchart28 _ ._ ._ .29 3031 . . . (conformance) . Traffic Policing Usage Parameter Control (UPC) . non-conforming (packet drop). . non-conforming conforming . Traffic Shaping . . Shaper Policer (UPC) .s1sNMUXShaperPhysical LayerFunctionsPHYSAPATN LayerPHY LayerEquivalent TerminalOther CPEFunctionsGeneratingTrafficDeviationsUPCTBTSPublic UNIPrivate UNI32 Shaper PolicerPolicer non-conforming . CLP ATM .Shaper Policer (Data Buffer) non-conformance conformance .UPC

UPC

ShaperData BufferConformingNon-conformingConforming33Policer33 ATM :Peak Cell Rate (PCR)1/T, where T is the minimum intercell spacing in secondsCell Delay Variation Tolerance (CDVT): number of cells that can be sent back-to-back at line speed is Sustainable Cell Rate (SCR)maximum average cell rateMaximum Burst Size (MBS)maximum number of cells can be sent at peak rateMinimum Cell Rate (MCR)minimum cell rate that needs to be guaranteed

PCR,SCR,MBS .34 UPC UPC : Leaky Bucket Window-based GCRA DEDTS

35 leaky bucket A minimum inter-arrival time is enforced between two consecutive departures. To produce a regulated output from an unregulated arrival process is called Traffic Shaping.

Arrival process:

Departure process:

Unregulated InputRegulated OutputT36 Leaky Bucket Shaper (Token Bucket)To implement traffic shaping, usually the concept of token as a permission to go or not to go is used. Leaky bucket contains tokens and not packets.When a token is available the next packet can depart. Otherwise, it has to wait in the buffer.Using the same concept, we can implement a traffic policer to determine whether a packet is conforming or not.Tokens can be used in units of bytes or packets.

RBoverflowNon-conformingconformingarrivalC

RBoverflowconformingarrivalCbufferShaperPolicer37Arrival of a packet at time taX = X - (ta - LCT)X < 0?X > L?X = X + ILCT = ta conforming packetX = 0NonconformingpacketX = value of the leaky bucket counterX = auxiliary variableLCT = last conformance timeYesNoYesNoDepletion rate: 1 packet per unit time

L+I = Bucket Depth

I = increment per arrival, nominal interarrival timeLeaky Bucket AlgorithmInterarrival timeCurrent bucketcontentarriving packetwould cause overflowemptyNon-emptyconforming packet3838 ( ) 39 (fair scheduling)

.

: 4040 .

: (Delay bound) (Jitter bound ) (Loss rate )4141 Internet telephony : E-commerce: E-mail : ( best effort service)

4242 End-to-End QoS :

PHB : Per Hop Behavior (hop) ( )

4343 PHB ( ...)

4444 Packet-Switched

4545 Packet-Switched (atomic ) ( : 64 1500)4646Isolate : circuit switched ( ) QoS IP traffic isolation . : 4747 () : : ( 6 64 Fast-Ethernet) . : handle .4848 FCFS (starvation) Work-conserving delay/jitter delay/jitter 4949 :

: 505015-2- FIFO: Round Robin: : Open-loop: : . Deadline : deadline Closed-loopZero-lossControlled delay

5151 52: ::

: ( ) (drop) (congestion )53 : ( congestion control ) : ( ) (Flows) .

(drop packet) . .- .54 aggressive

. .

55 : : - : -

56 drop Drop

Drop : real time TCP Drop Flush Drop 4

57 drop Non-real-time TCP : -> -> slow-start packet loss

Real-time UDP : -> error recovery . real-time ->

58

VN 1

VN 2

Physical Network

Transport

Network

Virtual

Networks

Virtual Path

Connections

Virtual Circuit

Connections

VN-1

VN-n

VPC-1

VPC-2

VPC-i

t

ABR BW

utilization

VBR BW

utilization

VBR VN BW

(Bvbr)

ABR VN BW

(Babr)

PBvbr

B

Cell-level

manager

Routing

Call

admission

control

Connection

manager

VP network

manager

VN

manager

Physical

network

manager

Buffer

management

Congestion/

flow control

Policing,

Scheduling

Connection

set-up and

release

VN link BW

manager

VP BW

manager

VP configuration

manager

VN configuration

manager

Physical link

BW manager

Network config-uration manager