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Network layer

Network layer. Doug Young Suh suh@khu.ac.kr Last update : Aug. 1, 2009. Network layer and realtime multimedia. Protocols for switching in the routers Routing = path + resource cf) direction + width of road IP header : IPv4 and IPv6 New features in IPv6

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Network layer

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  1. Network layer Doug Young Suh suh@khu.ac.kr Last update : Aug. 1, 2009 Network Layer

  2. Network layer and realtime multimedia • Protocols for switching in the routers • Routing = path + resource cf) direction + width of road • IP header : IPv4 and IPv6 • New features in IPv6 • Best Effort  per-class  per-flow • intServ. diffServ, MPLS MediaLab , Kyunghee University

  3. QoS control for networked video Upper Layers (Video Layer) Error resilience/concealment, scalability coding End-to-end UDP/RTP&RTCP, FEC, retransmission Transport Layer IP TOS, RSVP, intServ Network Layer FEC, retransmission, MAC Data Link Layer Power control Physical Layer Networked Video

  4. Network layer approaches • RSVP • intServ • diffServ • MPLS Video Layer 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. Networked Video

  5. Categories of QoS protocols Network QoS • Packet switching • Variable QoS (Best Effort) • Resource sharing • e.g. downloading data • Circuit switching or broadcasting • Fixed QoS • Dedicated circuit for a call • e.g. telephone • QoS switching • Guarantee reserved QoS • Resource allocation (dynamic) • e.g. realtime service QoS switching Per-class (coarse) : Packets are classified into several classes. 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.

  6. Per-class and per flow QoS services Per-class QoS service router I’m a class B packet. You, use the Gate B. After reading the temporary customer list for identification,,,,,,, Per-flow QoS service router 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].

  7. 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 QoS • Each flow has a temporary contract on QoS. • IntServ : identified by 5 tuples • 104 bits IPv4, 296 bits IPv6 • MPLS : identified by label PHB1 BA classifier PHB2 PHB3 intServ routing table 1 SA DA SP DP Pr TSpec 2 SA DA SP DP Pr TSpec 3 SA DA SP DP Pr TSpec 4 SA DA SP DP Pr TSpec 5 SA DA SP DP Pr TSpec Admission control classifier label SA DA SP DP Pr data Packet scheduler data

  8. RSVP/intServ • CAC by RSVP, call control by intServ

  9. RSVP parameters • Tspec (PATH), Rspec (RESV) • r : token rate • b : token-bucket depth • p : peak rate • m : minimum policed size • M : maximum packet size • Leaky bucket model [r,b], [p,M] Networked Video

  10. Resource reservation • When realtime service needs excess bandwidth, non-realtime service packets are buffered. Networked Video

  11. Diffserv Architecture r b ER marking Edge router: - per-flow service - marks packets of in- or out-profile Bandwidth Broker Core router: - per class service - buffering and scheduling - preference to in-profile packets - Assured Forwarding CR scheduling . . . Networked Video

  12. ER : Traffic Conditioning • Classifier of micro-flow w.r.t. agreed traffic profile • Marker : low, medium, high drop precedence Networked Video

  13. 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) PHB1 BA classifier PHB2 PHB3 Networked Video

  14. History of video/network IPv4 2G IPv6 3-4G H.261 MPEG-2 SVC ?? Circuit switching Broadcasting per class QoS Per flow QoS MPEG-4 & AVC ~AVC 2008 Fine QoS control, each media traffic of each individual service Packet switching : Best effort No QoS control, because everything is fixed. No QoS control, because network does not care. Coarse QoS control, [premium, medium, low, etc.]

  15. 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 frame • Intra > predictive > bi-directional • Scalable coding : base layer > enhancement layers • Error propagation and error resilience • Transport layer • Feedback of QoS metrics : loss/delay/bitrate • FEC : UEP/ULP (unequal error/loss protection) MediaLab , Kyunghee University

  16. IPv6 (IPng) • 128 bit address => 181018nodes, 4 nodes/cm2 • Ubiquitous networks • Hierarchical addresses • multicast, anycast => QoS aware broadcasting • Simplified header (for realtime sevice) • Improved security • Auto-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

  17. Version (4) Traffic Class (8) Flow Label (20) Version (4) HLEN (4) Type of Service (8) Total Length (16) Payload Length (16) Next Header (8) Hop Limit (8) Identification (16) Flags (3) Fragment Offset (3) TTL (8) Protocol (8) Header Checksum (16) Source Address (128) Source IP Address (32) Destination IP Address (32) Destination Address (128) Header formats of IPv4/IPv6 Networked Video

  18. IPv6 is reality. • Worldwide IPv6 network : tunneling-based • IPv6 routers : 3Com, Compaq, Ericsson Telebit, Hitachi Ltd., Nokia Telecom, Northern Telecom, • IPv6 Linux kernel • Windows NT, Windows 2000 • Future : wireless services in China, ubiquitous network Networked Video

  19. 8 4 4 104 8 111111111 000T Scope Multicast group address Multicast in IPv6 • T : permanent (0) or transient (1) • Scope : geographic scope (within node~global)

  20. Anycast in IPv6 3 5 8 32 16 64 010 Reg. TLA NLA SLA Interface ID • TLA, NLA, SLA : aggregators • Anycast : 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

  21. MIPv6 multimedia service Networked Video

  22. IntServ/RSVP Network Layer

  23. QoS Support in the Internet • Call admission control (CAC) traffic policing • by using signaling protocol • Traffic characteristics and requirements • Traffic shaping : User’s effort to keep promise • Traffic policing : Router’s effort to police CAC Traffic shaping Traffic policing Network Layer

  24. 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

  25. Resource reserVation Protocol (RSVP) • Previously, RFC1819 Internet Stream Protocol v2 (ST2+) referred as “IPv5” • RFC 2205 RSVP (1997) • RSVP and intServ : RFC 2210 • Signaling to reserve resource along the path of particular data streams or flows • Unicast and multicast • Multipoint to multipoint • Multipoint to single point Host RESV Router RESV Router RESV Router RESV Host PATH PATH PATH PATH Network Layer

  26. “PATH” and “RESV” Messages • “PATH” : from source to target • Marks the routed path and collects information about the QoS viability of each router along the path • “RESV” : from target to source • It 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, dynamicgroup membership, heterogeneous receiver requirements • “dynamic”=soft state : created/modified/removed Network Layer

  27. RSVP • What I am • originating application and sub-flow • such as print flow vs. time-critical transaction • Who I am • authenticated user ID • What I want • the 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

  28. RSVP modules in hosts and routers • ApplicationRSVP process • Admission control : sufficient available resources for the request? • Policy control : whether the use has permission for the reservation? Host Router control control Appli- cation RSVP process RSVP process Policy control Routing process Policy control RSVP data Admission control Admission control classifier classifier intServ Packet scheduler Packet scheduler data data Network Layer

  29. Reservation Request Spec.s • Filter spec. (logical) • Selection of subsets of the packets of a given session • Sender IP address and source port • To set parameters in the packet classifier • Flow spec. (quantitative) • Specification a desired QoS • Service class • Tspec (traffic descriptor) • Rspec (desired QoS parameters) • To set parameters in the node’s packet scheduler Network Layer

  30. RSVP parameters • Tspec (PATH), Rspec (RESV) • r : token rate • b : token-bucket depth • p : peak rate • m : minimum policed size • M : maximum packet size • Double leaky bucket model [r,b], [p,M] VBR : average rate < r < p CBR : average rate = r = p p <b r <M Network Layer

  31. Tspec/Rspec in RFC2210 Guaranteedservice Controlled load Network Layer

  32. RSVP Styles S1 S2 sender S1 S2 • Fixed-filter • All sender are active at all time. filter f f f f router N N 2f f receiver R R • One sender at a time • Wildcard-filter • e.g. audio conferencing • Shared explicit • The receiver select a sender.

  33. Scalability Problem SA DA SP DP Pr data • 3 step processes for every intServ packet • Identification of an intServ packet by 5 tuple classifiers {(SA, DA), (source port #, receiver port #), protocol} • Searching for the service spec. for the packet • Traffic policing and scheduling • Impossible inside core network • Maybe possible in edge routers of mobile network 1 SA DA SP DP Pr TSpec intServ routing table 2 SA DA SP DP Pr TSpec 3 SA DA SP DP Pr TSpec 4 SA DA SP DP Pr TSpec 5 SA DA SP DP Pr TSpec Admission control classifier Packet scheduler data Network Layer

  34. 5-tuples in IPv4 and IPv6 • 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 Network Layer

  35. MPLS (Multi-Protocol Label Switching) • Scalability problem of intServ • A set of 5 tuples  a temporary label • Virtual switch for the efficiency of routers (cf. ATM) • Connection oriented : VC (Virtual Circuit) • VC lookup table (resource, path) • Routing flexibility • Traffic engineering and provisioning • Constraint-based routing (QoS routing) • FEC (Forward Equivalence Class) • With RSVP  IPv6 “Flow Label” Networked Video

  36. Conclusions • intServ for per-flow service  IEEE801.16, UMTS~ • RSVP for resource reservation • Controlled load, guaranteed service • CAC  traffic shaping / policing • Scalability problem • MPLS, IPv6 flow label for simplified identification • Advanced approach • RFC4495 “RSVP Extension for Reduction of Bandwidth” (2006) • Draft-intserv-multiple-tspec (2010) • “…. to dynamically adapt to available bandwidth…” • Multiple reservations between two endpoints • Refreshes only include the Tspecs that were accepted MediaLab , Kyunghee University

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