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       Internet-The Next Generation:                                             • Background

          Developments in Internet
                                                                                 • Best-Effort Architecture
          Networking Technologies
                                                                                 • Emerging Architectures

                                                                                 • Conclusions

                                                                                 • References

                                                   Slide 1                                                                                                                        Slide 2

                    Background                                                                                     Background
• Origins of today’s Internet                                                                                         Sample Network
  – US Dept. of Defense DARPA projects (1960-70’s)                                                            Residential Internet
                                                                                                               (modem access)
  – Evolved from defense to research to commercial                                       LAN

• What is the Internet?
  – Hierarchical, global network of communicating hosts
  – Hosts have addresses, routers interconnect hosts                                                                          IP network
  – Routers perform packet switching, “best-effort” service                                                                    domains

                                                                                                     Intra d
                                                                                                         - omain                                             IP routers perform
                                                                                                     OSPF routing                                                   -
                                                                                                                                                               - y op
                                                                                                                                                             hop b h packet
• What is IP (Internet Protocol)?
  – Suite of protocols/framework to control routers/hosts              Various router link technologies
                                                                                                                                     - omain BGP
                                                                                                                                 Inter d
                                                                                                                                    routing (red)
  – Addressing, routing, registration, etc.                              (SONET/SDH, ATM, FR)

                                                   Slide 3                                                                                                                        Slide 4

                    Background                                                                                    Background
• Tremendous growth of IP-based networks
                                                                                                                                 Data traffic on large carrier
   – Worldwide deployment, many TCP/IP applications                                                                              networks exceeds voice
                                                                                                                                                     - 999)
                                                                                                                                 circuit traffic (1998 1
   – Hosts is growing exponentially, only few “on-line”                                                                                                              Internet applications:
                                                              Relative Traffic

                                                                                                                                                                     web browsing/caching,
   – Improving, cheaper “end-user” access technologies                                                                                                               ftp, telnet (exponential
                                                                                     Residential, business
      Link speeds increasing (cable, DSL, wireless)                                  trunked voice circuits
                                                                                                                                                                     growth scales)
                                                                                     (linear growth scales)
   – “Capacity requirements doubling per 4 months” (1999)                                                                                       Packet
   – Becoming crucial to economic/national infrastructure
• Changing networking paradigms: “circuit to packet”
   – Packet data volume has overtaken voice volume
   – Shift from “data over voice” to “voice over data”
                                                                                            1997                 1998             1999                   2000              2001
   – “Convergent network” philosophy
      I.e., “One network carries all (data, voice, video)”
                                                   Slide 5                                                                                                                        Slide 6
                    Background                                                                               Background
• Traditional IP user applications                                     • Challenges
   – Initial “data” applications (telnet, ftp, email,web)                 – Internet must evolve to support new applications
   – “Non-realtime” applications, no service guarantees                   – IP protocols must support service guarantees
       E.g., Web (ftp) transfer can take 1ms or 10 sec                        I.e., packet delay, loss, jitter
                                                                          – Must also support today’s IP protocols/applications
• New, emerging IP user applications                                          I.e., “Backwards compatibility” requirement
   – Recently, new “real-time” applications
      E.g., voice (IP telephony), IP video                             • New solutions are required
   – Future explosion of “multi-media” applications                       – “Intelligent” switching technologies
      E.g., Internet gaming, tele-commuting/conferencing                      I.e., Selective processing of traffic flows/types
   – Applications need services “guarantees”                              – Capable of supporting large, diverse user base
      E.g., Voice<10 ms delay, video<100 ms delay                             I.e., Commonly termed “scalability”
                                                                          – Various proposals have been made
                                                     Slide 7                                                                                                     Slide 8

            Best-Effort Architecture                                                             Best-Effort Architecture
• Represents traditional Internet architecture                                                    Traditional IP Network Hierarchy
   – “Hop-by-hop” forwarding (routing decision per packet)                                                                                                    - ffort”
                                                                                                                                                         “Best e
   – Very rudimentary packet buffering capabilities                Transport control, reliable               User Applications
                                                                                                                                                         services (e.g., web
                                                                                                                                                         browsing, ftp, telnet)
                                                                   transfer functions
      “First-in-first-out” (FIFO), G/G/1 model
   – Routing protocols for packet route control (static)          Traditional “best e
                                                                                   - ffort”                 TCP/UDP (Transport)
                                                                  layer three addressing,
      Open-shortest-path-first (OSPF) intra-domain                routing, packet forwarding

      Border-gateway protocol (BGP) inter-domain                                                               IP (Network)

                                                                                                      ATM       FR
• Best suited for “non-realtime” data applications               Variety of data and
                                                                                                                                                     Hardware (electronic
                                                                 link layer technologies                                  SONET Ethernet             buffering processing or
   – High delay tolerance (e.g., ftp, email)                     (costs, complexity)
                                                                                                                                                     SONET type opto  -
                                                                                                  SONET       SONET
                                                                                                                                                     electronic switching)
   – Reliability via higher-layer transport (TCP/IP)
   – Works well for lightly-loaded networks                                                                   Physical Layer
      I.e., Reduced packet losses, delays
                                                     Slide 9                                                                                                   Slide 10

            Best-Effort Architecture                                                             Best-Effort Architecture
• Inadequate service definition                                                                        FIFO Queueing Node (Edge)
                                                                                         - acket
                                                                            Constant inter p
   – Basic queueing gives no “quality of service” (QoS)                   timing, fixed packet size
      E.g., bandwidth (capacity), delay, loss, etc.
                                                                                                                                              Outgoing (combined) flows:
   – No service differentiation possible                                                                                                      voice timing very distorted
                                                                                    Time                             IP Router
   – Router processing speeds become bottleneck                 Voice packet stream (phone call)
      I.e., “Layer 3” IP address-lookup ( O(log2(N) )
   – Static routing causes network congestion                                                                                                             Time

                                                                                     - acket timing,
                                                                        Variable inter p
                                                                            variable packet sizes                                                   Fixed router
• Inefficient interworking with multiple “lower-layers”                                                        FIFO queue, voice and data      transmission link speed
   – Layered model approach (SONET/SDH, ATM, FR)                                                               packets mix (G/G/1 model)

      Added maintenance/operations costs, complexity                                Time
                                                                                                              Incoming (individual) traffic
   – Counter to convergent networks trend                         Data packet stream (web transfer)
                                                                                                                flows to IP router queue

                                                     Slide 11                                                                                                  Slide 12
                       Best-Effort Architecture                                                                         Emerging Architectures
                                 FIFO Queueing Network                                         • Revamp IP protocols/architecture
  User connection flows (e.g.,
TCP/IP or UDP session, dotted
                                              Router B                                            – New service definitions for “integrated” services
lines) buffered in same queues
                                                                                                    “Everything over IP networks” (voice, video, data)
                                                                                                  – Basic idea is to “separate out” different traffic types
       Router A                                                             Router D
                                                                                                     I.e., Treat “realtime” different from “non-realtime”
                                     Full-IP address lookup, single
                                                                                                  – Large focus in Internet Engineering Task Force (IETF)
                                    aggregate with large interference
                                        between multiple flows
                                                                                               • Multiple proposals have emerged:
                                                Router C
                                                                                                 – Integrated Services (IntServ) proposal
                                                                                                 – Differentiated Services (DiffServ) proposal
                                                                                                 – Multi-Protocol Label Switching (MPLS)*
                                                                                                    *Emerging as comprehensive solution

                                                                                Slide 13                                                                                         Slide 14

                  Emerging Architectures: IntServ                                                           Emerging Architectures: IntServ
   • Detailed, advanced service definitions                                                                              Per-Flow Queueing Node (Edge)
                                                                                                                 - acket
                                                                                                    Constant inter p
      – Multiple service categories                                                               timing, fixed packet size          IP IntServ Router
        Best-effort:          Like “best-effort” Internet
                                                                                                         Time                                                      Outgoing (combined) flows:
        Controlled-load:      Lightly-loaded Internet                                                                                                            limited voice timing distortion
                                                                                                                                          Flow 1
        Guaranteed:           Firm bounds (capacity, delay)
                                                                                           Voice packet streams                           Flow 2
   • Router requirements
                                                                                                           - acket timing,
                                                                                              Variable inter p                            Flow 3                         Fixed link speed
      – Advanced, fast packet classification/processing                                           variable packet sizes
         I.e.,IP-address lookup, complex buffering/scheduling                                                                                                      Per-flow bandwidth scheduler
                                                                                                                                          Flow 4
      – Admission control, scheduling, buffer management                                                Time
                                                                                                                                                                     gives capacity guarantees
                                                                                                                                                                  (hardware complexity: tracking,
      – Advanced resource control signaling (RSVP protocol)                                                                                                           processing/computing)
                                                                                                                                Per-flow buffering, voice and data
         For set-up and take-down of flow reservations                                                   Time                    packets separated (G/G/n model)
                                                                                           Data packet streams
      – Requires policy control (who makes reservations?)
                                                                                Slide 15                                                                                         Slide 16

                  Emerging Architectures: IntServ                                                           Emerging Architectures: IntServ
                             Per-Flow Queueing Network                                         • Shortcomings and concerns
      User connection flow (e.g.,       IntServ Router B
                                                                                                  – Per-user flow storage/processing for QoS at routers
       TCP/IP or UDP session)
                                                                                                     I.e., Potentially millions of flows at any time
                                                                                                  – Hardware complexity: storage, scheduling, monitoring
 IntServ Router A                                                       IntServ Router D
                                                                                                     E.g., Very fast (bounded) IP-address lookup times
                                                                                                  – Software complexity: RSVP protocol
                                                                                                  – Does not “scale”, i.e., if number of flows very large
                                 Per-flow buffering and
                            scheduling, complexity increases                                         Note: Same problem as ATM technology
                            with number of traversing flows
                                                                                                  – Traffic engineering limitations
                                         IntServ Router C

                                                                                               • Current status/developments
                                                                                                  – Complexity concerns have led to DiffServ proposal
                                                                                                  – RSVP being modified to suit DiffServ and MPLS
                                                                                Slide 17                                                                                         Slide 18
             Emerging Architectures: DiffServ                                                                  Emerging Architectures: DiffServ
   • Simplify per-flow model to per-class                                                                                     Per-Class Queueing Node (Edge)
                                                                                                                       - acket
                                                                                                          Constant inter p
      – Arrange (mark) user flow packets into classes                                                   timing, fixed packet size

          “Class of service” (CoS) indicated in IP header
                                                                                                                                           IP DiffServ Router         Outgoing (combined) flows:
      – Perform “per-class” control (buffering, scheduling)                                                     Time
                                                                                                                                                                     moderate voice timing distortion
          Via standardized “per-hop behaviors” (PHBs)
      – Much less complex than “per-flow” IntServ approach                                     Voice packet streams
                                                                                                                                                    Class 1
        I.e., O(# of classes) vs. O(# of flows)                                                                                                 1   1   1   1

                                                                                                    Variable inter p
                                                                                                                 - acket timing,                    Class 2                Fixed link speed
                                                                                                        variable packet sizes
   • Router requirements                                                                                                                            2       2

                                                                                                                                                                    Per-class bandwidth scheduler
      – Edge classification/metering (“mark” ToS byte header)                                                 Time
                                                                                                                                                                        (reduced complexity)

      – PHB resource mappings (% bandwidth,priority,buffer)
                                                                                                                                              DiffServ classification maps multiple
         E.g., Advanced buffer control (RED schemes)                                                           Time                           flows to fewer classes (two shown) by
                                                                                                Data packet streams                             “marking” ToS byte in IPv4 header
      – No signaling, “fixed” service level agreements (SLAs)
                                                                                  Slide 19                                                                                             Slide 20

            Emerging Architectures: DiffServ                                                                    Emerging Architectures: DiffServ
                            Per-Class Queueing Network                                              • Traffic aggregation problems
  User connection flows (e.g.,
                                            DiffServ Router B
TCP/IP or UDP session, dotted                                                                          – Class guarantees do not mean flow (user) guarantees
lines) mapped to fewer classes
                                                                                                          I.e., Flows inside a class can “collide/interfere”
                                                                          DiffServ Router D            – Good for small data transfers (web browsing)
     DiffServ Router A
                                                                                                       – Poor performance for real-time flows

                                     Per-class buffering/scheduling,                                • Limited flexibility
                                    complexity reduced to number of
                                 classes not number of traversing flows                                – Designed for relatively “static” networks
                                                                                                          Network topology, user traffic demands unchanging
                                              DiffServ Router C
                                                                                                       – Difficult to change class resource allocations
                                                                                                          E.g., Increase/decrease bandwidth per usage levels
                                                                                                       – Automated, fast re-adjustment required today
                                                                                                          I.e., Need “traffic engineering” applications
                                                                                  Slide 21                                                                                             Slide 22

                Emerging Architectures: MPLS                                                                         Emerging Architectures: MPLS
   • Very comprehensive framework
      – Decouple packet forwarding from routing                                                                                 IP-MPLS Network Hierarchy
         I.e., packet route setup before data transfer                                                                                                                           - ased” applications
                                                                                                                                                                            “QoS b
                                                                                                                                                                            (IP voice/video, Internet
      – Major industry focus (main IP networking framework)                                     Transport control, reliable
                                                                                                                                                                            gaming, etc.), and traditional
                                                                                                                                       User Applications                          - ffort” applications
                                                                                                                                                                            “best e
                                                                                                transfer functions
                                                                                                                                                                            (web browsing, ftp, telnet,
   • Based upon earlier flow/tag switching proposals
                                                                                                               - ware”
                                                                                              Layer three “QoS a
      – Assign “tags” to flows, switch based upon “tags”                                      routing/packet forwarding
                                                                                                                                     TCP/UDP (Transport)
                                                                                              and label b
                                                                                                       - ased forwarding,                                                    Hardware (electronic packet
      – Reduced delays for (layer 3) IP address-lookups                                       traffic engineering,                                                           buffering/processing and
                                                                                              protection/ restoration                                                        even optical switching)
      – Various tag assignment schemes (measure/control)                                                                            IP-MPLS (Network/Data)

   • MPLS enables many advanced applications                                                                                            Physical Layer

     – Traffic engineering, QoS service guarantees/routing
     – Virtual private networks (VPNs)
                                                                                  Slide 23                                                                                             Slide 24
                                 Emerging Architectures: MPLS                                                                                               Emerging Architectures: MPLS
  • “Label” and “label switched path” (LSP) concepts                                                                                                                           MPLS Label-Switching Node
                                                                                                                                                                  - acket
                                                                                                                                                     Constant inter p
     – Label: Identifier/tag used for switching data flows                                                                                         timing, fixed packet size

     – LSP: Concatenation of labels, arbitrary granularity                                                                                                                                                                       Voice distortion dependant upon
                                                                                                                                                                                                IP MPLS Router                    MPLS resource control (e.g.,
     – LSP achieves “virtual circuit”, i.e., logical connection                                                                                                                                                                       per-flow or per-class)

     – Encapsulate IP packets into MPLS packets (header)
     – LSP protection, label stacking (flow aggregation)                                                                                    Voice packet streams

                                                                                                                                                                                       Label encapsulation,

                                                                                                                                                                                         label swapping
                                                                                                                                                                                                              Generic resource
                                                                                                                                                            - acket timing,
                                                                                                                                               Variable inter p                                                control engine
  • Router requirements                                                                                                                            variable packet sizes                                         (buffering,
                                                                                                                                                                                                                                          Fixed link
     – Maintain input/output label tables, “short” label match                                                                                                                                                  scheduling)

     – Generic association of labels with local QoS resources                                                                                           Time                                                            Label encapsulated user
                                                                                                                                                                                                                     packets/datagrams (i.e., MPLS
        I.e., buffer space, priority, bandwidth                                                                                                                                                                             “shim” header)
     – Signaling protocols to control label assignments                                                                                                  Time                       MPLS packet mapping (via forward
                                                                                                                                            Data packet streams                       equivalent class, FEC), packet
        RSVP+extensions, label distribution protocol (LDP)                                                                                                                           encapsulation with MPLS header
                                                                                                                                 Slide 25                                                                                                        Slide 26

                                  Emerging Architectures: MPLS                                                                                                  Emerging Architectures: MPLS
                                 Label Table                      MPLS Network                                                                  • DiffServ implementation via MPLS
                       Link In    Label In   Link Out   Label
                                                                                                   Label-switched paths (incoming
                                                                     MPLS Router B
                                                                                                                                                   – Associate labels (LSPs) with aggregate classes

                         1          23          3        21
                                                                                                   labels overwritten with outgoing


                                    …          …
                                                5        27

                                                                                                  labels after switching, based upon                  I.e., Multiple flows (traffic classes) on to same label
                                                                                                          label table entries)
                                                                       Label control

                                                                                                                                                   – RSVP/LDP can now fill signaling shortcomings
                         5           3          1        89

                                                                                        control            MPLS Router D
MPLS Router A

                                                                                                                                                • IntServ implementation via MPLS
 Label control

                                                             Label processing operations
                                                                                                                                                   – Associate labels (LSPs) with each flow (connection)
                                                                                                             Label control

                 Resource                                     (edge mapping, swapping,                                       Resource
                                                           stacking): arbitrary granularity                                   control                 I.e., Each user (connection) has unique label (LSP)
                                                                 and resource control
                                                                                                                                                   – Note: Per-flow complexity, but can “stack” labels
                                                                     MPLS Router C
User connection flow (e.g.,
 TCP/IP or UDP session)                                                                                                                         • Extensions to optical networks
                                                                       Label control

                                                                                                                                                   – For migration from SONET/SDH technology
                                                                                                                                                   – Can apply “label” switching to wavelength switching
                                                                                                                                 Slide 27                                                                                                        Slide 28

  • Internet growth forecasted to grow tremendously
     – New applications, more bandwidth, more users
     – Increasingly integral to corporate/national success

  • Traditional “best-effort” IP model is inadequate
     – Designed for “latent” data traffic transport (ftp, email)
     – No multi-service guarantees (delay, loss, jitter)
     – Added costs complexity maintaining multiple networks
        I.e., IP, ATM, SONET/SDH, frame relay, etc.

  • Emerging advances promise much more
     – Service guarantees, traffic engineering, VPNs
     – MPLS has emerged as comprehensive framework
                                                                                                                                 Slide 29

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