The Verizon NGN - Challenges in Evolving to a Converged Network Prodip Sen Director, Packet Network Architecture Verizon Technology Organization June 1,

The Verizon NGN - Challenges in Evolving to a Converged Network

Prodip SenDirector, Packet Network Architecture

Verizon Technology Organization

June 1, 2007

© Verizon 2007 – All Rights Reserved Slide 2

Outline

• The Verizon NGN• Packet Network Convergence• Challenges and the Future


The Verizon NGN


STPSTP

DSLAMDSLAM

Switch Switch

ATMATMSwitchSwitch

Switch Switch

Tandem Tandem

FRFRSwitchSwitch

Gig-EGig-ESwitchSwitch

ATMATMSwitchSwitch

DCSDCS

RTRT

Inter-Office Inter-Office Transport Transport NetworkNetwork

Inter-Office Inter-Office Transport Transport NetworkNetwork

ATM/FRATM/FR NetworkNetwork

PSTNPSTN

IXCIXC

Network(s) of the Past

Cost of maintaining, growing and operating multiple technologies and networks is untenable.


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

MPLS

IP

Network Apps

Mesh and Ring DWDM

SONET, EPL

PBB, VPWS

G.709 (OTN)

Applications

Packet OpticalTransport Platform

Converged Packet Switch / Router

Service Delivery Platform IMS Core; IPTV Core

Next GenElements


FTTP -- MASS-MARKET BROADBAND ACCESS

OpticalSplitter

Central Office

Customer PremisesThird Wavelength Is Optional

ONT

Optical Coupler(WDM)

IP/MPLSNetwork

Internet

VoIPServices

PSTN/SS7Network

Super Head End (SHE)

EDFA

OLT

Bandwidth BPON

Downstream: 622 MbpsUpstream 155 Mbps

EDFA – Erbium Doped Fiber AmplifierOLT – Optical Line TerminalONT – Optical Network Terminal

IP Video Services

Industry Moving Towards GPON Systems– Doubles, Or Quadruples, Bandwidth– Enables Full IPTV Implementation– Uses Same Fiber Plant Design– Overlay Wavelength Decision (Vs. IPTV)

GPON1.2Gbps/2.4 Gbps622Mbps/1.2 Gbps


• 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)

Signaling Communication Network

GMPLS Signaling and Routing Messages

Broadband Service Control

Point

Wavelength Cross Connect (WXC)

CPC

CPC

CPC

CPC

CPC

Collector Rings


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)


LEC TDM

Strategic Packet Network Architecture

CPSL2SW

TDM

Ethernet

GPON

GPON

EthernetFR/ATMTDM

ADSL

DSLAM

MetroPrivate

Line

CPABEAS

NGOLT

ROADMNet

Ethernet

CPABEAS

LECEthernetAccess

NGEAR

CBBR

MSE

In Footprint Access

Out of Footprint Access

Verizon Business

NG VoIP,EnterpriseServices

WANLambda

OtherVPNs

Internet

External Networks

Verizon Telecom

Next GenEdge/

AggregationRouter

ConvergedBack-Bone

Router

Multi-ServiceEdge

Router

NG VoIP, ConsumerServices

Optical

Legend:

MetroFiber

ATMNG-GWR

VoD/ IPTV

FR/ATM

FR/ATM

UnderStudy

CPAL2SW

EthernetSwitch

SES

VZ Wireless


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

ProcessorRouting ProcessPhysical

Interface

LogicalInterfaces

Software Separation

SingleProcessor

Multiple Routing Processes

Hardware Separation

MultipleProcessors


LogicalInterfaces


Logical Interface Allocation


Forwarding Card AllocationLogical Interface Allocation

Forwarding Card Allocation

Software Separation

Some Separation, Least Cost

Some Separation, Least Cost

Hardware Separation

Good Separation, Higher Cost

Most Separation, Highest Cost

Distributed Processing Router

Multiple ProcessorsSingleRouting Process

Sub-Processes


Ethernet and MPLS Aggregation in the Access Network

LEC TDM

L2SW

Ethernet

GPON NGOLT

BEAS

In Footprint Access

Out of Footprint Access

Verizon BusinessVerizon Telecom

EthernetSwitch

L2SW L2SW L2SW

External Networks

EthernetNetwork

MS-PWL2VPN

On-netFiber

InternetAccess L3VPN

InternetAccess

L3VPN

MS-PW Segment Endpoint

TunnelTunnel

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 LCROLT

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

NGEARROADM

NetNGOLT

IP-MPLS Service Edge


Challenges and the Future

23


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 ?

The Verizon NGN - Challenges in Evolving to a Converged Network Prodip Sen Director, Packet Network Architecture Verizon Technology Organization June 1,

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