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Integrated-Service versus Differentiated-Service Networks. 許蒼嶺 教授 國立中山大學 電機工程學系. Department of Electrical Engineering Computer Networking Lab National Sun Yat-Sen University Prof. Tsang-Ling Sheu. Outline. Integrated Services Traffic Model RSVP Differentiated Services - PowerPoint PPT Presentation
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Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu
Integrated-Service versus Differentiated-Service Networks
許蒼嶺 教授
國立中山大學
電機工程學系
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 2
Outline
• Integrated Services– Traffic Model
– RSVP
• Differentiated Services– Architectures
– Traffic Classes and DSCP
– Queuing Disciplines
– Survey of Papers
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 3
Quality of Services
• Over-Provisioning
• Priority Queuing
• Per-Flow : Integrated Service, Intserv [RFC1633]
• Per-Class : Differentiated Services, Diffserv [RFC2475]
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 4
Integrated Services
• Resource ReSerVation Protocol
• Controlled-Load Service - RFC 2212
• Guaranteed Service - RFC 2211
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 5
Integrated Services
• Modules in Integrated-Service Traffic Model
– Admission Control• Determine if QoS Request Should be Granted
– Traffic Classifier• Map Packets/Flows to Service Classes
– Packet Scheduler• Forward Packets Based on Service Classes
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 6
IntServ Traffic Model
RSVPReservation
ClassifierPacket
Scheduler
RSVPReservation
Routing Protocols
AdmissionControl
ClassifierPacket
Scheduler
Host
Router
IP Data Flow
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 7
Integrated Services
• Guaranteed Services
– For Delivering Real-Time Applications
– Provides an Assured Level Services
• Bandwidth
• End-to-End Delay Bound
• No Queuing Loss
• Controlled-Load Services
– Service Equivalent to Best-Effort Flows
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 8
RSVP Issues
• RSVP only Suits for Long-Duration Applications
– Too Expensive for WWW Transfers
• RSVP only Suits for Small-Size Networks
– Leads to too many Link States and Signaling Traffic
• RSVP Requires Application Supports
– Knowledge of Application QoS
– QoS API
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 9
R S V P c lo u dS en d er
R o u ter R o u terR ece iv er
RSVP
(1 ) P A T H(2 ) P A T H
(3 ) P A T H
(4 ) R E S V
(5 ) R E S V(6 ) R E S V
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 10
Diffserv Architecture
D S C o re R o u te r
S o u rc e
D e s tin a tio n
D S D o m a in
D SD o m a in
D SD o m a in
E d g eR o u te r
E d g eR o u te r
D S In g re ssB o u n d a ry
R o u te r
D S E g re ssB o u n d a ry
R o u te r
Differentiated Services Domain
Differentiated Services Domain
Differentiated Services Domain
D ifferen tia ted S erv ices R eg io n
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 11
DiffServ Issues
• Scaling– Pushes Complex Forwarding Operations to Boundary Routers
• Control and management– Rely on New Configuration or Management Protocols
• Bandwidth Broker (BB)– Suits for a Small-Size Network
– Distributed BB
• Billing and Accounting– Based on Negotiated Traffic Profiles
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 12
Management and Billing Priority Levels
IP AddressesTCP Ports
Time of Day
WWW
FTP
Telnet
SMTP
SNMP
VideoConf.
BBS
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 13
Bandwidth Broker
Boundary Router
Boundary Router
InteriorRouters
Packets In
Packets Out
Bandwidth Broker
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 14
Diffserv Field in IPV6 Header
V ers io n 8 -b it T O S 1 6 -b it T o ta l L en g th (in b y tes)L en g th
1 6 -b it Id en tifica tio n F la g s 1 3 -b it F ra g m en t O ffse t
8 -b it T T L 8 -b it P ro to co l 1 6 -b it H ea d er C h eck su m
3 2 -b it S o u rce IP A d d ress
3 2 -b it D estin a tio n IP A d d ress
6 -b it D S C P C U
8 -b it T O SV ers io n 8 -b it T ra ffic C la ss 2 0 -b it F lo w L a b e l
1 6 -b it P a y lo a d L en g th N ex t H ea d er H o p L im it
1 2 8 -b it S o u rce IP A d d ress
1 2 8 -b it D estin a tio n IP A d d ress
8 -b it T ra ffic C la ss
6 -b it D S C P C U
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 15
Diffserv – PHB Group
• DF (Default Forwarding, Best-Effort)– DSCP : 000000
• EF (Expedited Forwarding)– DSCP : 101110
• AF (Assured Forwarding)– DSCP : 4 Class, 3 Drop Precedence
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 17
Classifier & Traffic Conditioner
M e te r
T ra fficC o n d itio n e r
C la ss if ie r M a rk e r S h a p e r/D ro p p e rP a c k e ts
C la ss if ie r M a rk e r S h a p e r/D ro p p e r C la ss if ie d
P a c k e ts
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 18
First-Come-First-Serve (FCFS)
• Simplest Queue• Packet will be dropped when queue is full• Rear or front dropping
1
Packet outPacket in
Server23456
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 19
Priority Queue (PQ)
• Packets with higher-priority will always be sent first
• Starvation in lower-priority queue
1
Packet outPacket in
High Priority Queue
Low Priority Queue
ServerClassifier
234
56
789
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 20
Round-Robin (RR)
Arrivals departuresLinkClassify
Queues
1
2
3
4
5
6
7
8
9
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 21
Weighted Round Robin (WRR)M. Katevenis, IEEE Journal on Selected Areas in Communications, 1991
• General case of Round Robin
• More weight with higher-priority class
1
Packet outPacket in
ServerClassifier
Weight = 3
Weight = 1
Weight = 2
13
14
23
4
56
789
10
1112
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 22
Weighted Fair Queue (WFQ)A. Demers, SIGCOMM’ 89
• Provide fairness in variable-length IP packets
• Packets sent by the order of estimated completion time
)),,(),,1(max(),( ikaikFikS )(
),(),(),(
tr
ikLikSikF
i
0
)( )(
)(
otherwise
tActiveSetiifw
wR
trtActiveSetjj
i
i
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 23
WFQ S(4,1)=F(3,1)=17
r1=20
Weight = 1
Weight = 3
Weight = 2
F(4,1)= 20
S(2,1)=a(2,1)=7
F(2,1)=9
0
L(1,1)/r1=80/20=4
time
a(4,1)=13
r2=10
r3=30
61720 7913
L(2,1)=40
L(3,1)=100
L(1,1)=80
L(4,1)=60
L(1,2)=40
L(2,2)=60
L(3,2)=60
L(1,3)=90
L(2,3)=150
L(3,3)=90
L(4,3)=90
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 24
Deficit Round Robin (DRR)M. Shreedhar, IEEE/ACM Transactions on Networking, 1996
• WFQ is not easy to be implemented, O(log P)
• DRR
– Round Robin fashion, O(1)
– Use Quantum instead of Weight
– Use Deficit Counter to provide fairness
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 25
DRR
200
250
150
150
150
150250
150
300
0
0
300
100
200
400
200150
CounterQuantum
200
250
150
150
150
150250
150
100
100
200
300
100
200
400
200150
1
2
34
5
6
7
8
9
10
11
CounterQuantum
(a) (b)
RR PointerRR Pointer
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 26
Token Bucket (TB)
• Leaky Bucket:Traffic Shaping
• Token Bucket:Shaping with more burst tolerance
LeakyBucket
CapacityC
BurstyTraffic
Constant RateR
TokenBucket
TokenCapacity bBursty
Traffic
Buffer Size
Constant Token Rater
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 27
Minimum Threshold (Minth)Maximum Threshold (Maxth)Average Queue Size (avg)Marking Probability (Pmax)
Random Early Detection (RED)
P (D ro p )
1
M in th M a x th
P m a x
a v g
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 28
Random Early Detection(RED)S. Floyd, IEEE/ACM Transactions on Networking, 1993
• Random drop or mark packets before buffer overflow
minth maxth0
maxp
1
Pb
avg
Qwavgwavg qq )1(
)1/( bba pcountpp
thth
thpb minmax
minavgmaxp
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 29
RED with In/Out Bit (RIO)D. D. Clark, IEEE/ACM Transactions on Networking, 1998
• Different marking probability for In/Out packet
min_out max_out0
Pmax_out
avg_totalmin_in max_in0
Pmax_in
1
avg_in
P(Drop_In) P(Drop_Out)
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 30
RED with In/Out bit (RIO)In Packet :
Minimum Threshold (Minth_in)Maximum Threshold (Maxth_in)Average Queue Size (avg_in)Marking Probability (Pmax_in)
Out Packet :Minimum Threshold (Minth_out)Maximum Threshold (Maxth_out)Average Queue Size (avg_total)Marking Probability (Pmax_out)
P (D ro p )
1
M in th _ o u t M a x th _ o u t
P m a x_ o u t
a v g _ in /a v g _ to ta lM in th _ in M a x th _ in
P m a x_ in
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 31
Proportional DiffServC. Dovrolis, IEEE Network, 1999
• Absolute DiffServ (WRR, DRR)– Use static resource reservation instead of dynamic resource reserv
ation
• Proportional DiffServ (WTP, DWFQ, PLQ)– Provide QoS differentiation between traffic classes– Predictable:
• High-priority class must have better or the same QoS as low- priority class
– Controllable• Provide a time tuning knob to adjust the differentiation betwee
n classes
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 32
Waiting Time Priority (WTP)C. Dovrolis, IEEE/ACM Transactions on Networking, 2000
• General case of Time-Dependent Priorities
[L. Kleinrock, Queuing Systems, 1976]
– Delay Proportional Parameter δi
– Active(Busy) Set B(t)
– Normalized Head Waiting Time
– Packet with the most waiting time will be sent first
iii twtw /)()(~
)(~maxarg
)(twj i
tBi
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 33
Dynamic WFQ (DWFQ)Chin-Chang Li, ICCCN, 2000
WFQScheduler
Class 1 buffer
Class 2 buffer
Class 3 buffer
Class n buffer
ClassiferPacket outPacket in
.
.
.
.
Arrival RateMeasurement
BacklogMeasurement
Weightadjustment
)2
1(
1:)
2
1(
1: UbUbvv k
jkj
j
ki
ki
i
kj
ki
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 34
Probabilistic Longest Queue (PLQ)Jung-Shian Li, GLOBECOMM’01
Logic Queue 1
Classifier Dropper Scheduler
Info-Component
Packet outPacket in Logic Queue 2
Logic Queue 3
Logic Queue 4 N
j jjiii QcQcP
N
j jjiii sQsQP
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 35
PQ with EF Token Bucket
• EF PHB has the highest priority
• Use a Token Bucket to limit EF maximum bit rate
EF
AF
Default
Token RateREF_Reserved
Priority 3
Priority 2
Priority 1
Server
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 36
Priority Queue with Quantum (PQWQ)
• Provide fairness between PHBs– Use counters for all PHBs in order to limit bytes sent in one round– Quantum values will be added to counters after one round
• Provide low delay to EF PHB– EF PHB has the highest priority– If counter is enough, higher priority PHB will be sent first in one r
ound– Avoid the delay by Round Robin fashion
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 37
PQWQ (cont.)
EF
AF
Default
Counter
Priority 3
Priority 2
Priority 1
Server
3000
Quantum
6000
1000
3000
6000
1000
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 38
Diffserv Potential Problems
1. Ineffectual End-to-End QoS guarantee2. Unfair bandwidth sharing3. Packets only dropped at congested links when congest
ion
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 39
Various Diffserv Architectures
1. Packet-Marking Engine (PME)[Wu-Chang Feng, 1999]
2. Feedback Controlled Diffserv[Hungkei Chow, 1999]
3. Diffserv in MPLS[Y. Bernt, 2000]
4. RSVP in Diffserv[I. Andrikopoulos, 1999]
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 40
Packet-Marking Engine (PME)
•New Packet-Marking Engine•TCP-like algorithm and Modified TCP congestion control•Dynamic Marking probability (mprob)
Adv :•TCP-friendly algorithms•Adative packet marking to improve end-to-end throughput•Traffic fairness
Disadv :•1-bit priority for packet marking•Support TCP traffic only•Update network interface in host/nodes
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 41
Feedback Controlled Diffserv•New FC-DS nodes•Probe/Report control packet•Adaptvie QoS
Adv :•Current network status report•Adative traffic conditioning•Fair network resources allocation
Disadv :•Upgrade DS nodes to support FC scheme•More processing complexity in FC-DS ingress nodes•Extra processing of probe control packets
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 42
Diffserv in MPLS
P H BM a p p e r
P H B -to -A T M
D iffse rvM o d u le
L D P D a e m o nD S -c o m p a tib le
T C P /U D P IP
R o u tin gD a e m o n
M P L SD a e m o n
G S M PIn te rfa c e
A d m iss io nC o n tro l
F lo w M IBC o n tro lle r
F lo wM IB
A T M D riv e r
S w itch C o n tro ller
A T M S w itchA T MM IB
L D P S e ss io n to L D P p e e r
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 43
RSVP in Diffserv
E n d -u ser d om ain(stu b n etw ork )
E n d -u ser d om ain(stu b n etw ork )
D S d om ain(tran sit n etw ork )
E d g eR o u te r
E d g eR o u te rB o u n d a ry
R o u te rsR S V P sig n a lin gIn tserv p a ra m etersT ra ffic S h a p in gP a ck et M a rk in g
A g g reg a te P o lic in g (B A )D iffserv P H BC a rr ies R S V P m essa g e
" T ra n sp a ren tly "
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 44
Self-Adaptive Diffserv Router
E g re ss In te rfa c e(c la ss ify , m e te r ,
a c tio n , q u e u e in g )P H B
R o u tin gC o re
In g re ss In te rfa c e(c la ss ify , m e te r ,
a c tio n , q u e u e in g )T ra ffic
C o n d itio n in g
S e lf-A d a p tiv eC o n tro lle r
D iffse rvc o n fig u ra tio n &
m a n a g e m e n tin te rfa c e
D a ta in
M a n a g e m e n t
S N M P ,C O P S
e tc .
D a ta o u t
Q o S &S e lf-A d a p tiv e
C o n tro l M e ssa g e s
Q o S &S e lf-A d a p tiv e
C o n tro l M e ssa g e s
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 45
D S E g re ssB o u n d a ry R o u te r
D S In g re ssB o u n d a ry R o u te r
D S C o reR o u te r
S o u rc e
D e s tin a tio n
E d g eR o u te r
E d g eR o u te r
D SD o m a in
D SD o m a in
D SD o m a in
D SD o m a in
Self-Adaptive Diffserv Architecture
(1 ) M eter in g an d P erform in gS e lf-A d ap tive A lgor ith m
(2 ) S en d in g S e lf-A d ap tive C on tro lM essages to In gress R ou ter if n eed ed
(3 ) R ece iv in gS e lf-A d ap tive
con tro l m essagesan d R e-m ark in gor R e-a lloca tin g
resou rces
(4 ) S en d in g R em ark ed F low M essages
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 46
Self-Adaptive Control Message Format
IP H ead e r T C P H ead e r O th e r S e lf-A d a p tiv e In fo rm a tio n (o p tio n a l)
S e lf-A d a p tiv e C o n tro l M e ssa g e
4 -b itv e rs io n
4 -b ith ead erlen g th
6 -b it O ldD S C P
C U 1 6 -b it to ta l len g th (in b yte s)
1 6 -b it id en tifica tio n 3 -b itf la g s 1 3 -b it frag m en t o ffse t
8 -b it tim e toliv e (T T L )
8 -b it p ro to co l 1 6 -b it h ead e r ch eck su m
3 2 -b it so u rce IP ad d re ss
3 2 -b it d es tin a tio n IP ad d ress
IP H ea d er
3 2 -b it seq u en ce n u m b er
3 2 -b it ack n o w led g em en t n u m b er
1 6 -b it T C P ch eck su m
1 6 -b it so u rce p o rt n u m b er 1 6 -b it d es tin a tio n p o rt n u m b er
4 -b ith ead erlen g th
6 -b it S A I(N ew D S C P )
URG
ACK
PSH
RST
SYN
FIN
1 6 -b it w in d o w s iz e
1 6 -b it u rg en t p o in te r
T C P H ea d er
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 47
6-Bit SAI Field
PHBDSCP Field
SAI Field
Description
EF 101110 0xxxxxxIncrease weight for
WRR
EF 101110 1xxxxxxDecrease weight for
WRR
AFOld
DSCPNew
DSCPChange to new DSCP
BE 000000 0xxxxxxIncrease weight for
WRR
BE 000000 1xxxxxxDecrease weight for
WRR
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 48
2-Bit CU Field
CU value Packet Type
00 Normal Data Packet
10 Normal Control Packet
01 Congested Data Packet
11 Congested Control Packet
Department of Electrical Engineering Computer Networking LabNational Sun Yat-Sen University Prof. Tsang-Ling Sheu 49
Conclusions• Integrated Services
– Per flow QoS
– RSVP
• DiffServ Architectures– Per Class QoS
– Traffic Classification
• Queuing and Scheduling– WRR, WFQ, DRR, Token Bucket, Proportional Delay, etc.
• MPLS and DiffServ
Recommended