DiffServ & MLPS. Séminaire à l université Badji Mokhtar Département informatique Annaba, Algérie, mai C. Pham

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1 DiffServ & MLPS Séminaire à l université Badji Mokhtar Département informatique Annaba, Algérie, mai 2012 C. Pham Université de Pau et des Pays de l Adour Congduc.Pham@univ-pau.fr 1

2 Service Differentiation N E W C H A P T E R The real question is to choose which packets shall be dropped. The first definition of differential service is something like "not mine. -- Christian Huitema Differentiated services provide a way to specify the relative priority of packets Some data is more important than other People who pay for better service get it! DiffServ SLA Service Level Agreement 2

3 Divide traffic into classes Differentiated IP Services Voice Platinum Class Low Latency Application Traffic , Web Browsing E-Commerce Traffic Classification Gold Silver Guaranteed: Latency and Delivery Guaranteed Delivery Voice Bronze Best Effort Delivery DiffServ Auteur: C. Pham, Université de Pau et des Borrowed Pays de l Adour from Cisco (UPPA) 3

4 DiffServ building blocks DIFFSERV TRAFFIC CONDITIONING SHAPING MARKING POLICY PER HOP BEHAVIOR TOKEN BUCKET INTRA-DOMAIN INTER-DOMAIN SCHEDULING (RR, WRR, FQ, WFQ) AQM (DT, RED, ) DiffServ 4

5 Traffic Conditioning User declares traffic profile (eg, rate and burst size); traffic is metered and shaped if non-conforming 5Mbps SLA 2Mbps Service Level Agreement packets classifier marker Shaper/ dropper DiffServ meter forward <= C bps r tokens per second b tokens drop regulator 5

6 Differentiated Architecture Ingress Edge Router DiffServ Domain Egress Edge Router Interior Router r marking scheduling Marking: per-flow traffic management marks packets as in-profile and outprofile b. Per-Hop-Behavior (PHB): per class traffic management Ingress buffering and scheduling based on marking at edge preference given to in-profile packets Egress DiffServ 6

7 Pre-defined PHB Expedited Forwarding (EF, premium): departure rate of packets from a class equals or exceeds a specified rate (logical link with a minimum guaranteed rate) Emulates leased-line behavior Assured Forwarding (AF): 4 classes, each guaranteed a minimum amount of bandwidth and buffering; each with three drop preference partitions Emulates frame-relay behavior DiffServ 7

8 Premium Service Example Drop always 10Mbps Fixed Bandwidth DiffServ Auteur: C. Pham, Université de Pau et source des Pays Gordon de l Adour Schaffee (UPPA) 8

9 Assured Service Example Drop if congested 10Mbps Uncongested Assured Service Congested DiffServ Auteur: C. Pham, Université de Pau et source des Pays Gordon de l Adour Schaffee (UPPA) 9

10 Border Router Functionality Premium Service Token Bucket Packet Input Data Queue Wait for token Set P-bit Packet Output Assured Service Token Bucket Class 1 Class 2 Class 3 Class 4 Low drop probability Medium drop proba High drop proba No token Packet Input DiffServ Test if token Token Set A-bit Data Queue Packet Output Auteur: C. Pham, Université source Gordon de Pau Schaffee, et des Pays modified de l Adour by (UPPA) C. Pham 10

11 Internal Router Functionality Packets In P-bit set? Yes High Priority Queue No Low Priority Queue Packets Out If A-bit set, a_cnt++ if congested If A-bit set, a_cnt-- RED In/Out Queue Management A DSCP codes aggregates, not individual flows No state in the core Should scale to millions of flows DiffServ Auteur: C. Pham, Université source Gordon de Pau Schaffee, et des Pays modified de l Adour by (UPPA) C. Pham 11

12 Scheduling DiffServ PHB relies mainly on scheduling choose the next packet for transmission FIFO: in order of arrival to the queue; packets that arrive to a full buffer are either discarded, or a discard policy is defined. More complex policies: FCFS, PRIORITY, EDD, RR, WRR, FQ, WFQ, DiffServ 12

13 Putting it together! 1 Drop probalility 0 1 WRED Queue 0 WRED Queue 1 0 1/4 1/2 3/4 Queue filling Prec. 0 BE + AF UDP out profile 30 % Queue 0 Prec. 1 AF UDP in profile 30 % 30 % Queue 1 Queue 2 Classifier Prec. 2 AF TCP out profile Prec. 3 AF TCP in profile Prec. 4 Prec. 5 EF Prec. 6 Control DiffServ 10 % Queue 3 Prec. 7 Control Auteur: C. Pham, Université de Pau et des Pays de l Adour Source (UPPA) VTHD 13

14 Bandwidth provisioning N E W C H A P T E R DWDM-based optical fibers have made bandwidth very cheap in the backbone On the other hand, dynamic provisioning is difficult because of the complexity of the network control plane: Distinct technologies Many protocols layers Many control software IP ATM SONET/SDH DWDM 14

15 Review of IP routing R3 A R1 D R4 D D D Ver HLen T.Service Total Packet Length B 20 bytes C Fragment ID Flags Fragment Offset TTL Protocol Header Checksum Source Address R2 Destination Destination Address Next Hop Options D (if any) R3 E Data R3 F R5 R5 E F 15

16 The telephone circuit view SW SW Trunk lines SW SW SW SW PABX PABX SW 16

17 Advantages of circuits Provides the same path for information of the same connection: less out-of-order delivery Easier provisioning/reservation of network s resources: planning and management features 17

18 Time Division Circuits Most trunks time division multiplex voice samples At a central office, trunk is demultiplexed and distributed to active circuits Synchronous multiplexor N input lines Output runs N times as fast as input Simple, efficient, but low flexibility and wastes resources N MUX Fixed bandwitdh N De- MUX N 1 sample every 125us gives a 64Kbits/s channel 18

19 Back to virtual circuits Virtual circuit refers to a connection oriented network/link layer: e.g. X.25, Frame Relay, ATM Virtual Circuit Switching: a path is defined for each connection A B C R3 R1 R2 R4 D E R5 But IP is connectionless! F 19

20 Virtual circuit principles Connections & Virtual circuits table Label IN Link IN Label OUT Link OUT label 23 R Link 1 Link A R1 R3 R4 D Virtual Circuit Switching B C E R2 R5 20

21 End-to-end operation (1) VCI E. Lien E. VCI S. Lien S. 17 A 1 A CR@B A 0 B 2 C 2 1 VCI E. Lien E. VCI S. Lien S B 2 C CR@B A 2 B 0 C 1 A 2 B 1 C 0 4 CR@B 13 VCI E. Lien E. VCI S. Lien S CR@B 5 B C VCI E. Lien E. VCI S. Lien S

22 End-to-end operation (2) VCI E. Lien E. VCI S. Lien S. 17 A 1 A data A 0 B 2 C 2 1 VCI E. Lien E. VCI S. Lien S B 2 C data A 2 B 0 C 1 A 2 B 1 C 0 4 data 13 VCI E. Lien E. VCI S. Lien S data 5 B C VCI E. Lien E. VCI S. Lien S

23 Why virtual circuit? Initially to speed up router s forwarding tasks: X.25, Frame Relay, ATM. We re fast enough! Now: Virtual circuits for traffic engineering! 23

24 Virtual circuits in IP networks Multi-Protocol Label Switching Fast: use label switching LSR Multi-Protocol: above link layer, below network layer Facilitate traffic engineering IP LINK PPP Header(Packet over SONET/SDH) PPP Header Header Layer 3 Header Ethernet Ethernet Hdr Header Layer 3 Header Frame Relay FR Hdr Header Layer 3 Header 24

25 From multilayer networks FR access ATM SONET/SDH ring SONET/SDH ring 25

26 to IP/ networks Multi-access Label Switch Router IP/ link 1 Multi-access U N I V E R S I T Y 26

27 operation 1a. Routing protocols (e.g. OSPF-TE, IS-IS-TE) exchange reachability to destination networks 1b. Label Distribution Protocol (LDP) establishes label mappings to destination network Label Switch Router 4. LSR at egress removes label and delivers packet IP link 1 IP 10 IP 20 IP src dest out * /16 1/10 * /16 1/26 2. Ingress LSR receives packet and label s packets 3. LSR forwards Source Yi Lin, modified C. Pham packets using label switching

28 Label Distribution In In dest out out Link label link label / Label Switch Router In In dest out out Link label link label / Label Switch Router link 1 Use label 20 for! /16! Use label 40 for! /16! Use label 10 for! /16! In In dest out out Link label link label In In dest out out Link label link label / / Unsolicited downstream label distribution 28

29 Label Distribution (con t) In In dest out out Link label link label / !? Label Switch Router In In dest out out Link label link label / Label Switch Router Use label 10 for! /16! link 1 Use label 20 for! /16! Use label 40 for! /16! request label for! /16! request label request for! label for! /16! /16! In In dest out out Link label link label In In dest out out Link label link label / / On-demand downstream label distribution 29

30 Dynamic circuits for grids E B C I need 2.5 Gbps between: A & B B & C D & C E & A A D 30

31 for resiliency FastReroute Intended to provide SONET/SDHlike healing capabilities Selects an alternate route in tenth of ms, provides path protection Traditional routing protocols need minutes to converge! FastReroute is performed by maintaining backup LSPs 31

32 for resiliency, con t Backup LSPs One-to-one Many-to-one: more efficient but needs more configurations C G A D F H B E One LSP from A to H 3 backup LSPs 32

33 for resiliency, con t Recovery on failures Suppose E or link B-E is down B uses detour around E with backup LSP C G A D F H B E 33

34 for VPN (Virtual Private Networks) Virtual Private Networks: build a secure, confidential communication on a public network infrastructure using routing, encryption technologies and controlled accesses Shared network 34

35 for VPN, con t The traditional way of VPN Uses leases lines, Frame Relay/ATM infrastructures 35

36 134.13/16 VPN B for VPN, con t VPN over IP/ IP/ replace dedicated networks reduces VPN complexity by reducing routing information needed at provider s routers /16 VPN B Know only attached VPNs /16 S /16 s /8 s1 Do not know VPNs at all VPN A VPN A Ingress LSR IP backbone Egress LSR IP VPN B /8 36

37 for optical networks Before Application Application Transport Transport Network Network Network Network Link WDM WDM Link Terminals IP router IP router Terminals Source J. Wang, B. Mukherjee, B. Yoo! 37

38 for ON, con t MPλS=+λ lightpath Application Application Transport Transport Network Link Network(IP) λ is MPλS viewed WDM as a label Network(IP) MPλS WDM Network Link Terminals MPλS enabled LSR MPλS enabled LSR Terminals Source J. Wang, B. Mukherjee, B. Yoo! 38

39 Summary Towards IP/(G)/DWDM From cisco 39

40 Summary Technology scope Source Alcatel 40

41 Want to know more? G: IEEE Comm. Mag., Vol. 43(7), July 2005 Optical Control Plane for the Grid Community: IEEE Comm. Mag., Vol. 44(3), March Optical Transport Systems/Networks by S. Kinoshita & R. Rabbat, APNOMS «Inter-domain Traffic Engineering for QoSguaranteed DiffServ Provisioning», Young-Tak Kim, APNOMS %203.pdf See Tutorial IV of HOTI 2006: Dynamic Optimal Networks for Grid Computing 41