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    • The Verizon NGN - Challenges in Evolving to a Converged Network Prodip Sen Director, Packet Network Architecture Verizon Technology Organization June 1, 2007
    • Outline
      • The Verizon NGN
      • Packet Network Convergence
      • Challenges and the Future
    • The Verizon NGN
    • Network(s) of the Past
        • Cost of maintaining, growing and operating multiple technologies and networks is untenable.
      STP DSLAM Switch ATM Switch Switch Tandem FR Switch Gig-E Switch ATM Switch DCS RT Inter-Office Transport Network ATM/FR Network PSTN IXC
    • Services Landscape
      • Demand for traditional wire line POTS is declining.
      • Customers are becoming more technically sophisticated with multiple devices requiring simultaneous broadband access.
      • The service model is changing from telephony-centric to data-centric – most new services and applications being developed, are IP / web based.
      • “ Any-to-any” connectivity - need to provide IP services to (enterprise) customers with multiple locations served via different Layer 1 or 2 access mechanisms.
      • Quality of Service (QoS), Service Level Agreements (SLAs) are becoming increasingly important.
      • Service flexibility is the key to success.
    • Business Drivers for Convergence
      • Business Drivers
        • Strategic Growth Services in which Vz will Invest
          • Ethernet, Internet Access, L3VPNs, L2VPNs, VoIP & Video Delivery
        • Layer 1 and 2 services (Frame, TDM, ATM) will continue to exist for the foreseeable future in their native form. Additionally these will provide access to IP services.
        • Services such as VoIP require rapid restoration and differentiated QoS
        • FTTP will markedly increase traffic volumes
      • Strategy
        • Design a core “multi-service” network to serve all customer segments
        • Use the converged network for new services - old technology will be migrated and retired within financial and regulatory constraints
        • Convergence to two layers in the core: optical transport and packet switching, on which all applications can served.
        • Complementing this evolution in the core network is the deployment of FTTP for broadband access.
    • Verizon’s Target – IP over Glass
      • Connectivity - Optical transport is the key to next-generation, bandwidth-intensive applications.
        • FTTx is replacing the copper plant over the next 10-15 years.
        • Expansion of Verizon’s installed fiber plant via DWDM.
          • ~3.5M strand-miles -> 3.5B λ -miles (pre-MCI merger)
        • Evolution from ring-based SONET transport using APS protection to mesh-based DWDM transport.
      • Access – Support legacy and new forms of access migrating to Ethernet
        • Frame, ATM, TDM need to be supported, but will be pushed to the edge and aggregated into the packet network.
        • Ethernet is the new access allowing for network convergence and significant savings.
      • Network - A QoS Enabled IP/ MPLS Network Provides Service Convergence.
        • Multiple overlay networks can be supported on a single core infrastructure, significantly reducing capital and operating expenses.
            • Many levels of logical groupings possible - Virtual Private LAN Services ( VPLS ) and IP Virtual Private Networks ( VPNs ), Logical Routers..
        • Aggregate forwarding in the core allows for significant scalability over traditional technologies.
        • Class-based queuing in conjunction with MPLS allows for QoS-differentiated service offerings, and quick failure-recovery.
      • Applications – Based on an IMS and IPTV infrastructure overlaid on top of the packet network.
    • Core Architecture Target Applications Packet Optical Transport Platform Converged Packet Switch / Router Service Delivery Platform IMS Core; IPTV Core Next Gen Elements MPLS IP Network Apps Mesh and Ring DWDM SONET, EPL PBB, VPWS G.709 (OTN)
    • FTTP -- MASS-MARKET BROADBAND ACCESS Optical Splitter Central Office Customer Premises ONT Optical Coupler (WDM) Super Head End (SHE) EDFA OLT Bandwidth BPON Downstream: 622 Mbps Upstream 155 Mbps EDFA – Erbium Doped Fiber Amplifier OLT – Optical Line Terminal ONT – Optical Network Terminal
      • Industry Moving Towards GPON Systems
        • Doubles, Or Quadruples, Bandwidth
        • Enables Full IPTV Implementation
        • Uses Same Fiber Plant Design
        • Overlay Wavelength Decision (Vs. IPTV)
      GPON 1.2Gbps/2.4 Gbps 622Mbps/1.2 Gbps Third Wavelength Is Optional IP/MPLS Network Internet VoIP Services PSTN/SS7 Network IP Video Services
      • Approach
        • Consolidate traffic types into a single network
        • Reduce total number of network elements
        • Reduce number of optoelectronic conversions between ingress and egress points
        • Eliminate unnecessary regeneration in the network
      • Integrated Multi-Service And Multi-Functional Elements in Metro
        • Service integration by providing full support for TDM/SONET/SDH, IP, Ethernet, ATM, and MPLS interfaces
        • Integration of aggregation, adaptation, switching, routing, and transport in A high-performance, cost-effective design
      • Transparent Optical Core
        • ROADM and WXC Platforms in Core Network
        • Mesh Topology – Dedicated Protection
      Optical Network Convergence Strategy
    • The Core Optical Network Nationwide 10 Gbps Per Wavelength Network (40G Ready) Supporting Mesh Topology Re-Configurable Optical ADM (ROADM) 3000 – 4000 Km Reach without regeneration Optical Cross Connect (OXC) Wavelength Cross Connect (WXC) Collector Rings Signaling Communication Network GMPLS Signaling and Routing Messages Broadband Service Control Point CPC CPC CPC CPC CPC
    • Packet Network Convergence Strategy
      • Platform Convergence
        • Reduce number of routers and interfaces to decrease Capex/Opex
        • L2 access network backhauls traffic to converged edge/aggregation routers
        • Multiple services supported via a converged edge/aggregation router
        • New services enabled by deploying new cards rather than new platform deployment
        • Common platforms enable convergence of testing, operations and OSS Development for different business units
      • Network Convergence
        • Eliminate service specific networks, but maintain diverse customer access with unified access into the VZ packet network
        • Converge the backbone network and maintain logical networks based on class of service sets rather than individual service
        • Maintain logical control and capacity separation between service sets (e.g., public, private)
    • Strategic Packet Network Architecture LEC TDM CPS L2SW TDM Ethernet GPON GPON Ethernet FR/ATM TDM ADSL DSLAM Metro Private Line CPA BEAS NGOLT ROADM Net Ethernet CPA BEAS LEC Ethernet Access NGEAR CBBR MSE In Footprint Access Out of Footprint Access Verizon Business NG VoIP, Enterprise Services Other VPNs Internet External Networks Verizon Telecom Next Gen Edge/ Aggregation Router Converged Back-Bone Router Multi-Service Edge Router NG VoIP, Consumer Services Optical Legend: Metro Fiber ATM NG-GWR VoD/ IPTV FR/ATM FR/ATM Under Study CPA L2SW Ethernet Switch SES VZ Wireless WAN Lambda
    • Packet Network Convergence
    • Target Packet Network Characteristics
      • Service Support
        • Uses MPLS VPNs and PseudoWires for service domain and customer differentiation.
        • Implements QoS to provide differentiated treatment of traffic types.
        • Stable platforms and network resiliency mechanisms to provide PSTN-”like” availability.
      • MPLS Model
        • IS-IS is the IP topology construction technology.
        • MPLS is the transport technology.
        • LDP is the initial MPLS signaling technology, with RSVP-TE phased in.
        • BGP is the VPN membership discovery technology.
      • QoS Model
        • DiffServ combined with MPLS traffic engineering is used to provide end-to-end QoS across multiple domains.
        • NEs at the boundaries of a domain perform traffic control functions (e.g., policing, marking, MPLS COS mapping).
        • Interior NEs perform bandwidth management functions (e.g., aggregate queuing, WRED).
    • Convergence Enablers -- Router Design
      • Carrier class routers emerging at last !
        • Higher capacity, high availability, multi-chassis, diversity of service cards
      • Software Process Separation
        • Multiple routing processes run on the same physical processor with operating system limits placed on key parameters
      • Logical Interface Allocation
        • Each logical interface (e.g., DLCI, VLAN) can be owned by a separate process
      • Hardware Processor Separation
        • Each routing process runs on a physically separate processor
      • Implementing Resiliency
        • Fast Failure Detection (e.g. BFD)
        • Non-stop forwarding via graceful restart or hot routing/signaling redundancy
      • Forwarding Separation
        • Class-based queuing, scheduling, policing and shaping
        • MPLS bandwidth reservation
        • VPN-based forwarding
    • Convergence Enablers -- Hardware and Protocols
      • High-performance Ethernet Forwarding Hardware
        • High-speed, cost-effective interfaces
        • QoS capable, policing, shaping per logical interface
        • Supports link aggregation, protection switching, OAM
      • Ethernet-capable Optical Equipment
        • New generation of optical aggregation and switching elements have Ethernet and MPLS processing capability
      • Tunnel-based Traffic Engineering and Constrained Routing
        • MPLS support currently available
        • Ethernet-based tunneling may be an expected future standard
      • Automatic Logical Circuit Provisioning, Routing, Restoration
        • Recent Multi-Segment Pseudowire (MS-PW) signaling and routing standard provides scalability and inter-provider interconnection
        • MS-PW protection and diversity routing being standardized as well
    • Logical Router Technology – Separation/Allocation Traditional Router Switch Forwarding Cards Processor Routing Process Physical Interface Logical Interfaces Software Separation Single Processor Multiple Routing Processes Hardware Separation Multiple Processors Multiple Routing Processes Logical Interfaces Multiple Routing Processes Logical Interface Allocation Multiple Routing Processes Forwarding Card Allocation Distributed Processing Router Multiple Processors Single Routing Process Sub- Processes Most Separation, Highest Cost Good Separation, Higher Cost Hardware Separation Some Separation, Least Cost Some Separation, Least Cost Software Separation Forwarding Card Allocation Logical Interface Allocation
    • Ethernet and MPLS Aggregation in the Access Network LEC TDM L2SW Ethernet GPON NGOLT BEAS In Footprint Access Out of Footprint Access Verizon Business Verizon Telecom Ethernet Switch L2SW L2SW L2SW External Networks Ethernet Network MS-PW L2VPN On-net Fiber Internet Access L3VPN Internet Access L3VPN MS-PW Segment Endpoint Tunnel Tunnel Legend MS-PW Segment NGEAR MSE Open Third Party Interface
      • Multi-Segment Pseudowire (MS-PW) switching provides any-to-any, automatic, traffic engineered virtual connections
      • MPLS or Ethernet Tunnels provide scalability within a domain
      • L2 protocol interworking supports connections with different protocols at the end points
      Ethernet VLANs Ethernet VLANs MS-PW MS-PW
    • FTTP Access Aggregation – Functional Convergence
      • Optical transport technologies with integrated Ethernet switching (e.g. OTP) provide OPEX & CAPEX reduction for traffic aggregation in the access network
      • Functionally decompose the edge GateWay Router into the NGOLT, OTP and the Next Gen Edge/Aggregation Router
      SONET ADM GWR LCR OLT NGOLT OTP NGEAR Current Deployment Target Architecture
    • Example : Splitting BRAS Functions Current View Edge routing forwarding, 2547, vlan, Diffserv Sub queuing, policing, etc. Subscriber Management (policy, DHCP, ..) PON Core: routing, forwarding, MPLS, queuing, QoS, etc. OLT Aggregation Routing Aggregation GWR Access L4+ L2-L3 L1
    • Example : Splitting BRAS Functions Target View Edge routing forwarding, 2547, vlan, Diffserv Sub queuing, policing, etc. Subscriber Management (policy, DHCP, ..) PON Core: routing, forwarding, MPLS, queuing, QoS, etc. OLT Aggregation Routing Aggregation Access L4+ L2-L3 L1 Forwarding, Diffserv Subscriber-queueing, Policing, IGMP, Multicast forwarding, Anti-Spoofing, ARP IP-MPLS Service Edge NGEAR ROADM Net NGOLT
    • Challenges and the Future
    • Where Are We?
      • We are attempting to
        • Merge separate networks.
        • Introduce fundamentally new technology in several areas simultaneously
      • While
        • Technology and standards are evolving
        • Legacy technology and network elements remain and have to be cared for
      • We need to
        • Shift in thinking from circuit-switching to packet-switching.
        • Change our operations paradigm and processes
          • New IP technologies are more like the Internet, less like the PSTN.
          • New technologies and strategies are forcing convergence in networks and network elements.
          • Multiple groups may need to touch the same elements and networks.
      • Need help in the management plane – new technology dies on the vine if not operationally viable
    • Inter-Provider / Inter-Network Challenges
      • Interconnection requirements driven by
        • services requiring inter-provider connectivity and end-end QoS guarantees (e.g., VoIP, global IPVPN services)
        • the regulatory regime
        • connecting existing networks
      • Specifying and achieving performance across domains
        • Common definitions of performance metrics across boundaries.
        • Apportioning performance when traffic crosses multiple carrier networks.
        • Enforcing SLAs across provider networks.
      • Achieving resiliency across providers / networks
        • MPLS is still optimized for intra-domain applications
        • Inter AS control plane is designed for stability and scale – not performance.
        • Inter AS TE, Fast-Reroute, Inter-carrier OCh restoration technology are still in their infancy.
      • Troubleshooting across the boundary
    • Beyond MPLS
      • High speed forwarding
        • Faster, bigger routers - are IP address lookups no longer an issue?
      • Separation of control and forwarding
        • Separate control processors and forwarding engines – is the separation then just a matter of better network element design?
      • Advanced services (VPN etc) and service separation
        • Better implementations of routing contexts and logical routers – can these be enough for service separation?
      • Improved resiliency and TE
        • Will IP fast reroute and the lack of useful tools to handle MPLS TE complexity, overtake the use of MPLS?
      • Encapsulating services
        • Will handling legacy native layer 1 and layer 2 services via encapsulation be the only reason left to use MPLS?
    • Convergence and Simplifying the Core - Are We There Yet?
      • In the current model for handling convergence are our networks any less complex?
        • E.g. the ATM control plane exists between CPE and bet end switches, IP control plane between “core” routers and interworking between the two at the boundaries.
        • Legacy Layer 1 and 2 switching is preserved, together with the new MPLS switching
        • Issues with QoS mappings, path visibility, points of failure
      • Are we moving complexity from the edge back into core?
        • Are the next generation elements more complex failure prone devices?
      • Should we be building true label switches to simplify the core ?