Network layer and realtime multimedia
Protocols for switching in the routersRouting = path + resource
cf) direction + width of road
IP header : IPv4 and IPv6New features in IPv6
Best Effort per-class per-flowintServ. diffServ, MPLS
23年 4月 19日 MediaLab , Kyunghee University
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Networked Video
QoS control for networked video
Physical Layer
Data Link Layer
Network Layer
Transport Layer
Upper Layers
(Video Layer)End-to-end
Error resilience/concealment, scalability codingUDP/RTP&RTCP, FEC, retransmission
IP TOS, RSVP, intServ
FEC, retransmission, MAC
Power control
Networked Video
Network layer approaches
RSVPintServdiffServMPLS
Transport Layer
Over-provision or QoS control?Internet service will be charged.IPv6 doesn't give a solution for the QoS
issue. IPv6 has the potential.
Video Layer
Categories of QoS protocols
Circuit switching or broadcasting • Fixed QoS• Dedicated circuit for a call e.g. telephone
Network QoS
Packet switching • Variable QoS (Best Effort)• Resource sharing e.g. downloading data
QoS switching • Guarantee reserved QoS• Resource allocation (dynamic) e.g. realtime service
QoS switching1.Per-class (coarse) : Packets are classified into several classes. 2.Per-flow (fine) : A flow could be a media stream of a certain service. Call admission control is required for resource reservation with all routers along the path.
Per-class and per flow QoS services
I’m a class B packet.
You, use the Gate
B.
I’m a video packet for the video-phone
service between John and Susan.
We provide you QoS of
[5Mbps, 10-5 packet loss,
and 1ms delay].
After reading the temporary customer list
for identification,,,,
,,,
Per-class QoS service
Per-flow QoS service
router
router
QoS identification for every video packet
per-class QoS : 8 bit TOS (TC) in the IP header
BA (behavior aggregate) classifier PHB : EF and AF(4 classes with 3 levels)
per-flow QoSEach flow has a temporary contract on QoS.IntServ : identified by 5 tuples
• 104 bits IPv4, 296 bits IPv6MPLS : identified by label
SA DA SP DP Pr data
Admission control
Packetscheduler
classifier
data
SA DA SP DP Pr TSpec1SA DA SP DP Pr TSpec2SA DA SP DP Pr TSpec3SA DA SP DP Pr TSpec4SA DA SP DP Pr TSpec5
intServ routing table
label
BA
classifier
PHB1
PHB2
PHB3
RSVP/intServ
CAC by RSVP, call control by intServ
Networked Video
RSVP parameters
Tspec (PATH), Rspec (RESV) r : token rateb : token-bucket depthp : peak ratem : minimum policed sizeM : maximum packet size
Leaky bucket model [r,b], [p,M]
Networked Video
Resource reservation
When realtime service needs excess bandwidth, non-realtime service packets are buffered.
Networked Video
Diffserv Architecture
Edge router:- per-flow service
- marks packets of in- or out-profile
Core router:
- per class service
- buffering and scheduling
- preference to in-profile packets- Assured Forwarding
CR scheduling
...
r
b
ER markingBandwidth Broker
Networked Video
ER : Traffic Conditioning
• Classifier of micro-flow w.r.t. agreed traffic profile• Marker : low, medium, high drop precedence
Networked Video
CR : traffic management
BA (behavior aggregate) classifier PHB
EF : guaranteed service, WFQ (weighted fair queuing)AF : 4 classes with 3 levels (high, medium, low drop procedure levels), RED (random early discard)
BA
classifier
PHB1
PHB2
PHB3
History of video/network
Packet switching :Packet switching :Best effortBest effort
per class QoSper class QoS Per flow QoSPer flow QoS~AVC
SVC
??Circuit switchingCircuit switching
BroadcastingBroadcasting
H.261MPEG-2
IPv4IPv42G2G
IPv6IPv63-4G3-4G
MPEG-4& AVC 200
8
No QoS control, because
everything is fixed.
No QoS control, because
network does not care.
Coarse QoS control, [premium, medium, low,
etc.]
Fine QoS control, each
media traffic of each individual
service
Revisit QoS of upper layers.Video layer
Feedback rate control Realtime encoding : quality vs. bitrate (R-D)Non-realtime encoding : Scalable coding
VBR(natural) and CBR(forced rate control)Multiple levels of significance
Partition A, B, C in a frameIntra > predictive > bi-directionalScalable coding : base layer > enhancement layers
Error propagation and error resilience
Transport layerFeedback of QoS metrics : loss/delay/bitrateFEC : UEP/ULP (unequal error/loss protection)
23年 4月 19日 MediaLab , Kyunghee University
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Networked Video
IPv6 (IPng)
128 bit address => 181018nodes, 4 nodes/cm2
Ubiquitous networksHierarchical addressesmulticast, anycast => QoS aware broadcasting
Simplified header (for realtime sevice)Improved securityAuto-configuration
plug-play network access (DHCP, ND)micro-mobility
QoS awareness traffic class (8 bits) flow label (20 bits, cf. VC of ATM)
Networked Video
Header formats of IPv4/IPv6
Version(4)
TrafficClass (8)
Flow Label (20)
Payload Length (16)Next
Header (8)Hop
Limit (8)
Source Address (128)
Destination Address (128)
Version(4)
HLEN(4)
Type ofService (8)
Total Length (16)
Identification (16)Flags(3)
FragmentOffset (3)
TTL (8) Protocol (8)Header Checksum
(16)
Source IP Address (32)
Destination IP Address (32)
Networked Video
IPv6 is reality.
Worldwide IPv6 network : tunneling-basedIPv6 routers : 3Com, Compaq, Ericsson Telebit, Hitachi Ltd., Nokia Telecom, Northern Telecom,IPv6 Linux kernelWindows NT, Windows 2000Future : wireless services in China, ubiquitous network
Multicast in IPv6
T : permanent (0) or transient (1)Scope : geographic scope (within node~global)
111111111000T Scope Multicast group address 8 4 4 104 8
Networked Video
Anycast in IPv6
010 Reg. TLA NLA SLA Interface ID
3 5 8 32 16 64
TLA, NLA, SLA : aggregatorsAnycast : A group of hosts or
routers can have the same address and provide the same service. Clients are connected to the nearest server. (cf: local broadcasting stations)
anyTV.co.kr
Networked Video
MIPv6 multimedia service
IntServ/RSVP
Network Layer
QoS Support in the InternetCall admission control (CAC) traffic policing
by using signaling protocolTraffic characteristics and requirements
Traffic shaping : User’s effort to keep promiseTraffic policing : Router’s effort to police
Network Layer
CAC
Trafficshaping
Trafficpolicing
Scheduling (queuing) algorithms
FIFO (First In First Out)Weighted fair queuing (WFQ)Deficit round robin (DRR)Stochastic fair queuing (SFQ)Round robin (RR)Strict priority
Network Layer
ReSource reserVation Protocol (RSVP)
Previously, RFC1819 Internet Stream Protocol v2 (ST2+) referred as “IPv5”RFC 2205 RSVP (1997)
RSVP and intServ : RFC 2210Signaling to reserve resource along the path of particular data streams or flows
Unicast and multicastMultipoint to multipointMultipoint to single point
Network Layer
Host RouterRouterRouter HostPATH PATH PATH PATH
RESVRESVRESVRESV
“PATH” and “RESV” Messages
“PATH” : from source to targetMarks the routed path and collects information about the QoS viability of each router along the path
“RESV” : from target to sourceIt the target wants, reserves resources along the path
Routers can “merge” downstream reservations to the same stream.State is maintained as long as “PATH” and “RESV” messages flow.Receiver driven (compared to broadcasting)
Large group, dynamic group membership, heterogeneous receiver requirements “dynamic”=soft state : created/modified/removed
Network Layer
RSVPWhat I am
originating application and sub-flow such as print flow vs. time-critical transaction
Who I am authenticated user ID
What I wantthe type of QoS service needed
How much I want certain applications quantify their resource requirements precisely.
How I can be recognized the 5-tuple classification criteria by which the data traffic can be recognized
Which network devices resources will be impacted by the associated data traffic
Network Layer
RSVP modules in hosts and routers
ApplicationRSVP processAdmission control : sufficient available resources for the request?
Policy control : whether the use has permission for the reservation?
Network Layer
Appli-cation
RSVPprocess
Policy control
Admission control
Packetscheduler
classifier
data
data
Routingprocess
RSVPprocess
Policy control
Admission control
Packetscheduler
classifier
data
Host Router
intServ
control
control
RSVP
Reservation Request Spec.sFilter spec. (logical)
Selection of subsets of the packets of a given sessionSender IP address and source portTo set parameters in the packet classifier
Flow spec. (quantitative)Specification a desired QoS
Service classTspec (traffic descriptor)Rspec (desired QoS parameters)
To set parameters in the node’s packet scheduler
Network Layer
RSVP parametersTspec (PATH), Rspec (RESV)
r : token rateb : token-bucket depthp : peak ratem : minimum policed sizeM : maximum packet size
Double leaky bucket model [r,b], [p,M]
Network Layer
p
bp
rb
r<b
<M
pVBR : average rate < r < pCBR : average rate = r = p
Tspec/Rspec in RFC2210
Network Layer
Guaranteed serviceControlled load
RSVP Styles
Fixed-filterAll sender are active at all time.
S1 S2
N
R
ff
2f
S1 S2
N
R
ff
f
One sender at a time Wildcard-filter
e.g. audio conferencing
Shared explicit The receiver select a
sender.
sender
filter
receiver
router
Scalability Problem3 step processes for every intServ packet1. Identification of an intServ packet by 5 tuple classifiers
{(SA, DA), (source port #, receiver port #), protocol}
2. Searching for the service spec. for the packet
3. Traffic policing and scheduling
Impossible inside core network Maybe possible in edge routers of mobile network
Network Layer
Admission control
Packetscheduler
classifier
data
SA DA SP DP Pr TSpec1SA DA SP DP Pr TSpec2SA DA SP DP Pr TSpec3SA DA SP DP Pr TSpec4SA DA SP DP Pr TSpec5
intServ routing table
5-tuples in IPv4 and IPv6
Network Layer
Flow ID : 104 bits in IPv4 and 296 bits in IPv6 IPv4 104 = 32*2 (SA, DA) + 32(SP, DP) + 8
(protocol) Scalability problem in public network ~NN
Class ID : 6 bits in DS field diffServ
Networked Video
MPLS (Multi-Protocol Label Switching)
Scalability problem of intServA set of 5 tuples a temporary labelVirtual switch for the efficiency of routers (cf. ATM)
Connection oriented : VC (Virtual Circuit)VC lookup table (resource, path)
Routing flexibilityTraffic engineering and provisioningConstraint-based routing (QoS routing)FEC (Forward Equivalence Class)
With RSVP
IPv6 “Flow Label”
ConclusionsintServ for per-flow service IEEE801.16, UMTS~
RSVP for resource reservationControlled load, guaranteed service
CAC traffic shaping / policing
Scalability problemMPLS, IPv6 flow label for simplified identification
Advanced approachRFC4495 “RSVP Extension for Reduction of Bandwidth” (2006)Draft-intserv-multiple-tspec (2010)
“…. to dynamically adapt to available bandwidth…”Multiple reservations between two endpointsRefreshes only include the Tspecs that were accepted
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