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Metropolitan IP Networks

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  • 1. Metropolitan IP Transport Networks Eric A. Voit Distinguished Member of Technical Staff Technology Verizon November 8 th , 2000  Copyright Verizon Communications, 2000. All Rights Reserved Disclaimer: The views expressed herein are those of the author, and do not necessarily reflect the position of Verizon. Note View Slides in PowerPoint ‘ Slide Show’ format
  • 2. Agenda
    • Economic drivers and architectures for Metropolitan IP Networks
    • The importance of efficient facilities utilization
    • More on IP QoS
  • 3. Long Live IP
    • IP divorces applications from transport
      • Value added services will be IP based
      • IP allows services to be delivered independently of the data link technology
      • Customers want to exploit price-performance curves of access technologies while having each of these technologies inter-operate
    • IP QoS has arrived
      • IP QoS mechanisms can be applied to specific applications of individual customers
      • IP QoS is superior to ATM QoS for IP transport
    • IP will be used for networks, ATM remains a viable link layer technology
      • DLECs currently provide integrated IP services using ATM transport. As lower cost link layer technologies are deployed (such as Gigabit Ethernet/Fiber), DLECs will abandon ATM.
  • 4. Review of Router Types and Business Segments
    • Access Router (AR)
      • Provides local (End Office) access to the IP network
      • Supports a variety of access technologies (e.g. ATM (DSL) , Fast Ethernet, FR)
      • Ensures the proper treatment of traffic based on an individual customer interface
      • Off the shelf equipment
    • Interconnection Router (IR)
      • Provides interconnection with external IP networks
      • Ensures the proper treatment of traffic to meet QoS and Customer VPN needs
      • Off the shelf equipment (potentially uses the same platform as the Router)
    • Router (R)
      • Provides efficient IP transport between nodes of the network
      • Ensures the proper treatment of traffic to meet QoS and Customer VPN needs
      • AR and IR must also perform the functions of the Router
      • Off the shelf equipment
  • 5. A New Yorker’s View of the World
  • 6. A DLEC View of the IP World DLEC Metro IP Application Services ISP Application Services DLEC Metro IP Network ISP Networks AOL UUNET SBC GTE-I Sprint Yahoo Application Transport
  • 7. Network Topology and Server Placement Local
    • Very high bandwidth
    • Low capital per installation
    • Limited local operations
    • Security / Network demarcation
    Centralized
    • Control Systems
    • Quickly changing data
    • LATA wide resources
    • Expensive platforms
    Off Net
    • Low volume services
    • Minimal QoS needs
    • World wide customer base
    • Embedded applications
    Distributed
    • High bandwidth
    • Low Latency
    • Local PSTN interconnection
  • 8. Scope of Metropolitan IP Network Latency Jitter Packet Loss Packet Sequence Bandwidth Security Availability Service Level Agreements (SLA) at IP Network Interfaces are Negotiated based on Application Specific Needs Application SLA Application SLA
  • 9. End-to-End Service Level Agreements
    • An application layer budget needs to be partitioned between sub-systems
    • SLAs need to be measurable and actionable
  • 10. AR Integrates Diverse Transport Technologies
    • Access Router acts as universal IP edge device for diverse customer access methods
      • Inexpensive equipment from a highly competitive evolving marketplace
    • Access technologies only supported as new services demand them (incremental roll-out)
    • Sharing the IP WAN infrastructure allows AR to push further to the edge
  • 11. The Key to Access Scalability Decoupling Logical and Physical Link Layer Termination
    • Router Port 1
      • Multiple ATM VCs from a DSLAM
    • Router Port 2
      • Ethernet access ‘Channelized’ for Fiber to the home
    • Router Traffic engineering is based on offered load and the number of logical connections, not physical port limitations
    Dozens of Twisted Pair One Fiber Layer 2 identity based on VPI/VCI Dozens of Feeder Fibers Hundreds of Drop Fibers Several Fibers (redundancy)
  • 12. Metropolitan IP Routing Topology
    • Logical
      • Redundancy and failover supported by proven routing protocols & implementations
      • Opportunity to efficiently route local and InterLATA IP traffic
    • Physical
      • Router connections engineered using the most efficient / expedient transport alternatives
      • Can change without impacting logical design
    Engineering Decisions
  • 13. Routing and Interconnection Logical Topology
    • Metro is built from multiple local areas
    • Local areas are connected to ensure redundancy and performance
    • Content services can be centralized, or distributed to the edge
    • Interconnection with ISPs is centralized to minimize operations complexity
  • 14. Network Topology and the Importance of Efficient Facilities Utilization
  • 15. 1996-1999 Data Networks
    • Which of the following statements are true:
    • IP, ATM, and SONET layers exist as independent aggregations of signaling, transport, and operations protocols and equipment
    • This layering results from historical accident
    • For networks carrying IP, this layering is based on sound long term engineering principles & economics
    Network Provider ATM / FR Network Provider SONET Network Provider Fiber Customer IP LAN Customer IP LAN
  • 16. Architectural Drawbacks for Local Data
    • Can require more than 6x the SONET ring bandwidth of an IP/SONET connection
    • Why? SONET was designed assuming a local PSTN switch that could choose a local trunk group. Star data architectures are unable to leverage this ability.
      • The current architecture was developed when data volumes were low, switches were expensive, and operations procedures and expertise was evolving
      • The current architecture is best when data traffic isn’t local
    • At some point, local data volumes become large enough for the economics to favor the deployment of data switches and routers closer to the edge of the network
      • Any economic analysis would have to measure the amount and characteristics of the local data to determine the opportunity for savings
      • The analysis would then focus on facilities cost versus switch placement, operations, and maintenance costs
      • An unlikely analysis conclusion would be to simply distribute more switches and routers across our existing SONET …
    Layer 2 Switch Example: Two customer routers, both connected to a Layer 2 Cloud via PVCs x2 Customer owned Routers
  • 17. Installing a Switch (or Router) on Every SONET Ring Doesn’t Completely Solve the Problem
    • If a switch or router was placed on every SONET ring, you would still double the data bandwidth required between two local offices (compared to a direct SONET connection)*
    • Adding a second switch on the ring in some cases will TRIPLE the SONET bandwidth required
    • Optimizing SONET utilization (for local data) requires switching capability in every C.O.
      • Optimizing SONET costs doesn’t mean you have optimized total service delivery cost
      • Today operational, service, and complete network topology roadblocks hinder such a network configuration
      • Architectures which address these problems are emerging
      • Price points for equipment and operations are changing, and are different than when Fast Packet services were first deployed
    * This example intentionally ignores the benefits of multiplexing traffic to multiple destinations, both local & remote. x2 Bandwidth x3 Bandwidth
  • 18. SONET also ‘Wastes’ Bandwidth
    • This fiber run is carrying an OC-12 worth of ‘wasted’ bandwidth. With traditional SONET, you cannot use this available capacity to transport low priority traffic.
      • (Note: this is not PoS interface protocol issue.)
    Logical Physical
  • 19. Gigabit Ethernet & 10GBE over Fiber
    • Enabling Factors:
    • Dark fiber
    • New Routers
      • ASIC & FPGA
      • Low latency
      • Big backplanes (50+ GB/s)
      • Line Speed QoS
        • Layer 3/4
      • 802.3ad
      • Interrupt driven failure recovery
    When is the cost of leased fiber (over diverse paths) lower than SONET?
  • 20. Ethernet / Fiber Organizational Interfaces
    • Different Organizations would manage the Routers and the Transport Layer
      • Different skill sets for Operations
      • Useful life of long haul Lasers is longer than life of Router
      • Ethernet provides a simple interface within the C.O.
      • Same network interface for Router to Router and Router to Customer communications
      • DWDM can be deployed to transport multiple Ethernet handoffs from the Routers
      • Regulatory boundaries
  • 21. DLEC Local Topology & Existing Tariffs
    • Verizon Transport Alternatives
    • ATM
      • DS3
      • OC3
    • SONET
      • DS3, OC3 on shared ring
      • Dedicated OC48 ring (OC12 drops to AR)
    • Dark Fiber
    DLEC Local Topology Airline perimeter around the four C.O.s Urban (10 miles) Rural (50 miles)
  • 22. Verizon Recurring Monthly Tariffs (FCC Tariff #1, 3 year commitment)
    • P er VC Charges excluded
    *
  • 23. More on IP QoS
  • 24. Why IP QoS is Superior to IP/ATM QoS
    • Applications talk IP
    • IP routers can now identify IP application layer traffic flows, and prioritize them across the LAN (i.e. QoS)
    • Supporting IP flow QoS in the WAN is now becoming viable
    • If IP QoS is deployable, having an intervening ATM QoS abstraction is redundant, unnecessarily restrictive, and costly
      • QoS prioritization is done on the AR
      • Eliminates the need for the different types of ATM pipes
      • Eliminates traffic management and operational complexities of different pipes
      • Minimizes troubleshooting between the IP and ATM layers
    • Managing QoS is now something customers can outsource to the network. They don’t have to pre-sort their IP traffic into different types of ATM QoS differentiated VC pipes
  • 25. Moderate ATM Cell Loss Can Induce Disproportionate IP Packet Loss 4% of Cells 4% of Packets 40% of Packets * 4% of Packets DLEC discards: IP/ATM IP Subscriber experiences loss of: