INTEGRATING OPTICAL TRANSPORT INTO ROUTERS

Transcription

1 WHITE PAPER INTEGRATING OPTICAL TRANSPORT INTO ROUTERS Tunable Laser-Based Interfaces and Multiplexing Options for 10-Gbps and 40-Gbps Applications Copyright 2010, Juniper Networks, Inc. 1

2 Table of Contents Executive Summary Introduction Tunable Juniper Networks 10-Gigabit Ethernet DWDM PIC DWDM Advantages in Metro Networks Features of Juniper Networks 10-Gigabit Ethernet DWDM PIC Solution Applications: Intra- and Inter-POP Configurations Limitations of Competing OC-768 Integration Solutions Juniper Networks Solutions Economic Advantages of Juniper Solutions Conclusion For More Information Data Sheets Documentation for Tunable Juniper Networks 10-Gigabit Ethernet DWDM PIC Features About Juniper Networks Table of Figures Figure 1: Hierarchical LSPs in GMPLS Figure 2: DWDM in metro area network Figure 3: 10-Gigabit Ethernet DWDM PIC Figure 4: Router with SR-to-DWDM transport for long-haul network Figure 5: 40-Gbps transponder targeting long-haul and dark fiber applications Figure 6: External third-party transponder: OC-768 approach Figure 7: 4-Port OC-192 approach Figure 8: Dark fiber application with four-fiber or single-fiber solution Copyright 2010, Juniper Networks, Inc.

3 Executive Summary This white paper should be read by network operators and managers, as well as executives. It describes applications and features of Juniper s tunable optics, and 10 Gbps and 40 Gbps options for Ethernet and SONET. Service provider networks both metro and core continue to converge on technologies that enable operational efficiencies and high-bandwidth multiplay offerings for consumer and business users. On the physical layer, this means optimal use of fiber via dense wavelength-division multiplexing (DWDM). On Layers 2 and 3, this means Ethernet and IP/MPLS. Of course, SONET/SDH remains an important framing technology as well, partly because many metro networks have already been built using ring topologies. In this convergence effort, situations often become apparent in which combining the functions of previously disparate network elements offers network simplicity and retains the service-building advantages of the overlay networks being replaced by the converged network. In particular, network operators have found that integrating optical transport technology into routers provides flexibility in provisioning that leads to the rapid rollout of new services, while allowing Layer 3 intelligence to ensure prompt responses to topology changes. Being able to extend the DWDM capabilities to the router without the need for fixed DWDM termination equipment allows providers to offer on-demand services. Juniper Networks supports several methods for integrating routing intelligence with an optical network. The tunable Juniper Networks 10-Gigabit Ethernet DWDM PIC uses a single tunable laser to access any of 45 possible International Telecommunication Union (ITU) grid wavelengths for customized compatibility with a multiplexed fiber network. Operators can thus streamline traffic patterns and reallocate wavelengths as bandwidth patterns change. Similarly, the 4-port OC-192 PIC uses 10-gigabit small form-factor pluggable transceiver (XFP) optics (with 80 km DWDM options) to achieve network compatibility. In a process known as inverse multiplexing, the 4-port OC-192 PIC supports 4 OC-192 ports that can aggregate to a full OC-768 frame. This scenario supports OC-768 transmission through an 80-km metro or intercity deployment. Favorable capital and operational economics are also seen with these PICs. For example, the 10-Gigabit Ethernet DWDM PIC sources 45 channels, but only one model number requires sparing. In addition, the wavelength can be configured and reconfigured remotely through the command-line interface (CLI), in response to network dynamics. On the other hand, the 4-port OC-192 supports full-frame OC-768 transmission without the need for expensive optical amplification over an 80-km span. Introduction DWDM continues to gain prominence in both metro and long-haul networks with the promise of continuing to provide ever-greater bit rates on the same fiber infrastructure. It will become even more important in the future as service providers continue to look for ways to easily deploy new services to subscribers without extending expensive fiber infrastructure. DWDM can provide advantages that many service providers are demanding in critical areas: Reduced need to lay new fiber, by building on the existing fiber infrastructure Cost effectiveness, by enabling rapid rollout of new services Flexibility to support a variety of data formats and transmission speeds High availability with built-in redundancy and failover mechanisms, along with advanced optical diagnostics and monitoring capabilities Of course, for maximum benefit, the provisioning of DWDM has to be nimble. Operators have been seeking ways to enhance the flexibility of wavelength services, and they want their optical bandwidth to be optimized for maximum revenue. One of the interesting developments in the drive to speed up provisioning is the tunable laser interface. The capability to change the wavelength via software control provides the agility needed for on-demand provisioning. In contrast to interfaces that need to be preset to a particular wavelength, tunable laser interfaces can also reduce sparing requirements, as one spare laser interface (that is, one model number) can back up several different-wavelength interfaces. Another important development in this area is the reconfigurable optical add/drop multiplexer (ROADM), which represents a step-function increase in manageability over traditional optical add/drop multiplexers (ADMs). Traditional ADM devices provide the capability to add and drop wavelengths from one network to another (for instance, from a metro ring to a local access ring, or from a metro ring to a service point of presence, or POP. However, operators would have to demultiplex an entire band of wavelengths just to add or drop a few wavelengths, potentially affecting circuit availability. Using a ROADM, operators can use software to add, drop, or parse any combination of available wavelengths. Copyright 2010, Juniper Networks, Inc. 3

4 The management standard integrating optical transport equipment such as ROADMs with routing infrastructure is Generalized MPLS (GMPLS). GMPLS extends the MPLS control plane to support packet switching, time-division multiplexing (TDM) switching, DWDM wavelength switching, and the switching of all traffic from one physical port to another. GMPLS does this by setting up a label switched path (LSP) hierarchy, so that router-to-router traffic has a particular LSP, as does ROADM-to-ROADM traffic and so on. This approach is based on IP routing and signaling, and can be controlled from routers for maximum operational efficiency. For instance, in Figure 1, all the LSPs (called highorder, low-order, and forwarding-adjacency, or FA, LSPs) can be controlled by the router. Low-order LSP Sonet/SDH ADM Switch DWDM Switch FA LSP DWDM Switch Sonet/SDH ADM Switch Low-order LSP High-order LSP High-order LSP ATM Switch ATM Switch Figure 1: Hierarchical LSPs in GMPLS Thus, GMPLS can manage all the network elements: routers, ROADM devices, and DWDM transport equipment. Juniper is an industry leader in GMPLS integration, supporting this feature with logical routers and with OC-768 links. 1 Another innovation that Juniper brings to the 40-Gbps application is the capability to create an OC-768 connection over 80 km by using inverse multiplexing with the 4-port OC-192 PIC. All these innovations are discussed in this document. Tunable Juniper Networks 10-Gigabit Ethernet DWDM PIC The tunable 10-Gigabit Ethernet DWDM PIC is a Type-3 PIC that operates on the Juniper Networks M320 Multiservice Edge Router, T320 and T640 Core Routers. This PIC supports 1024 VLANs and many other Ethernet features. 2 With this DWDM PIC, optical diagnostics are accessible through the Juniper Networks Junos operating system command-line interface (CLI) Included are numerous alarms, which generate system logs, and which can be trapped via SNMP. 3 When a wavelength being generated by the tunable 10-Gigabit Ethernet DWDM PIC is changed, the same adjustments can be made to other network equipment using GMPLS. One key economic advantage is that only one spare needs to be in force for up for four DWDM PICs: because they are tunable, the wavelength can be changed to match whatever PIC needs to be replaced. Other key advantages relate to the flexibility and the remote provisioning capabilities, both of which translate into reduced time to market. They are discussed in the following sections. 1 See the press release at 2 See the data sheet for the Tunable 10-Gigabit Ethernet DWDM PIC by clicking the Modules tab at 3 For a list of the ITU wavelengths and CLI commands to change them, see Documentation for Tunable Juniper Networks 10-Gigabit Ethernet DWDM PIC Features later in this document. 4 Copyright 2010, Juniper Networks, Inc.

5 DWDM Advantages in Metro Networks Figure 2 shows a typical metro network with multiple buildings and campuses connected through a DWDM ring. Each of the four separate networks is connected to the DWDM ring of single-mode fiber. Local routers (such as the M320, T320, or T640) integrate traffic from the customers local IP networks for transport over the network. The ring architecture delivers superior protection and reliability by connecting the DWDM multiplexers in the core of the network with the local routers through both directions of the optical ring. COMPANY D M Series COMPANY A M Series 1 GE 1 GE M Series DWDM Switch DWDM Switch Metro Access Ring 10 GE DWDM Switch M Series 1 GE 10 GE COMPANY C COMPANY B Figure 2: DWDM in metro area network The advantages of this approach are speed, scalability, high availability, and investment protection: Speed: DWDM can combine multiple optical signals over different channels on a single strand of fiber, and each signal can be transmitted at different rates, such as OC-12, OC-48, or OC-192. Providers have the option of providing more and faster links without the need for major structural changes in either the customer network or provider infrastructure. Scalability: Providers can scale the services supported over installed fiber by an order at least equivalent to the number of ITU-defined channels. Scalability to support new services or customers means an available wavelength on existing fiber reducing or eliminating the need for major network reconfiguration. Multiple end-user networks can be connected to different channels in a single strand of fiber, leaving unused channels available for future expansion and scalability. High availability: The architecture is inherently reliable, with built-in redundancy and failover mechanisms. DWDM can reroute around a ring failure in less than 100 ms. Further, two-path links to the ring from the end-user network deliver a unique wraparound capability that provides protection from fiber cuts. Investment protection: Both end users and service providers benefit from the investment protection inherent in a DWDM network. End users connect to the DWDM network by implementing advanced solutions such as the 10-Gigabit Ethernet DWDM PIC, which is fully integrated into standard Juniper Networks routing platforms such as the M320, T320, and T640. Juniper also delivers the advantage of support for tunable optics in the 10-Gigabit Ethernet DWDM PIC so the customer can easily modify (via the Juniper Networks CLI) the wavelength and channel used without making any changes to the PIC hardware or optics. Further, because the PIC is tunable, one spare is sufficient to back up multiple PICs. Copyright 2010, Juniper Networks, Inc. 5

6 Features of Juniper Networks 10-Gigabit Ethernet DWDM PIC Solution Juniper Networks M320, T320, T640, and TX Matrix routing platforms support DWDM with the addition of the 10-Gigabit Ethernet DWDM PIC (Figure 3). The 10-Gigabit Ethernet DWDM PIC implements tunable optics technologies that enable customers to use the full ITU grid, selecting from 45 wavelengths (C-band ITU grid with 100-GHz spacing) that can be configured from the CLI, with an optical reach of up to 80 km (49.6 miles). Software-programmable DWDM configuration: The 10-Gigabit Ethernet DWDM PIC enhances DWDM flexibility by supporting programmable configuration for 45 different wavelengths (100-GHz spacing in C-band from to nm) on a single line of fiber. With tunable optics technology, customers can select from the full ITU grid of channels on a single PIC module. Customers can easily add or delete different wavelengths from a common sparing inventory as bandwidth and network requirements change. The setting of DWDM wavelengths requires no change in PIC hardware or optics as the Junos OS CLI is used. Reduced cost of ownership: The 10-Gigabit Ethernet DWDM PIC expands cost savings by providing Figure 3: 10-Gigabit Ethernet DWDM PIC support for all 45 wavelengths available in a single PIC with one 10-Gigabit Ethernet optical interface. Other vendors require a different (physical) optical interface for every DWDM wavelength in the network, creating an operational burden as operators must match the right optical interface to the right module in the right location. Sparing each of the 45 individual DWDM optical interfaces is then a concern as well. Extended reach, to 80 km: The 10-Gigabit Ethernet DWDM PIC is ideally suited for network configurations that require both longer spans and the capability to use installed fiber. Supporting transmission distances of up to 80 km (49.6 miles) and passive DWDM multiplexers, the Juniper Networks solution delivers maximum flexibility for both intra-pop configurations and more distributed configurations. High-density DWDM configuration: Each 10-Gigabit Ethernet DWDM PIC supports up to 10-Gbps data transmission and, as shown in Table 1, Juniper can support up to 128 DWDM PICs in a single system (TX Matrix). Table 1: Juniper Networks 10-Gigabit Ethernet DWDM PIC PLATFORM PER CHASSIS PER RACK M T T T TX Matrix N/A 128 (per TX Matrix) 6 Copyright 2010, Juniper Networks, Inc.

7 Applications: Intra- and Inter-POP Configurations The applications of the 10-Gigabit Ethernet DWDM PIC for the 40-Gbps market can be separated into two primary areas: Intra-POP connections between routers Intersite handoff for POP egress The intra-pop application is a straightforward deployment of interfaces between routers to alleviate congestion; a 40- Gbps interface either displaces or augments a deployed link aggregation solution. High-speed connections egressing the POP typically rely on DWDM transmission systems to handle the movement of data between locations. Short-reach (SR) interfaces are used between the router and the local DWDM equipment. In this type of configuration (Figure 4), the data goes through an optical-electrical-optical (OEO) conversion on the transponder located in the DWDM system. The router originates an optical signal and sends it via an SR connection to the DWDM transponder. The transponder then performs the OEO conversion. The OEO conversion is required to convert the signal for transmission over the long-haul network. The OEO conversion also enables the signal to be integrated into a composite signal along with other similar discrete signals. DWDM SYSTEM Lambdas Short Reach Transponders Long-Reach Signal Management Multiplexer Figure 4: Router with SR-to-DWDM transport for long-haul network In the inter-pop application, the long-reach (LR) output on each transponder is tuned to a specific wavelength. In this configuration, the optical multiplexer is a passive element, consuming no electrical power and using the physical properties of its construction to achieve its function. In a DWDM system, much of the intelligence of the system the management and engineering expertise required to integrate the constituent subsystems lies in the transponder. In the ongoing process of optimizing the costs of network elements in converged networks, it has been postulated that savings can be achieved by moving the transponder function into the router. The idea is that the cost of the SR interface can be saved if the router integrates the transponder s functions. To achieve this result and maintain functional parity, the integrated transponder must assume the management responsibilities previously housed in the DWDM system. In a DWDM system, one of the primary responsibilities of the management subsystem is ensuring the integrity of the composite long-haul signal exiting the system. A variety of analog optical parameters must be accounted for in continuous operational management of the DWDM system. This approach raises some issues related to management differences for 10- and 40-Gbps transponders. The standard building blocks for DWDM transmission systems on the market today are 10-Gbps components. However, some technologies allow a 40-Gbps stream to be transmitted over the same spectrum as used by a 10-Gbps stream: a single 40-Gbps wavelength can be co-located with 10-Gbps wavelengths in an existing DWDM system. The necessary caveat in this scenario is that management of these disparate wavelengths needs to be addressed. Copyright 2010, Juniper Networks, Inc. 7

8 Limitations of Competing OC-768 Integration Solutions Figure 5 shows an integrated 40-Gbps transponder configured for traditional long-haul and dark fiber applications. DWDM SYSTEM Lambdas Long Reach Transponders Composite Long-Reach Signal Management Multiplexer Figure 5: 40-Gbps transponder targeting long-haul and dark fiber applications However, incumbent operators typically have a transmission group responsible for DWDM systems that is distinct from the data group responsible for routers. Thus, the transmission group must be willing to host an alien lambda (wavelength) on its line system. The router s interface must attach directly to the passive optical multiplexer, which means that it bypasses the typical management interface and controls for the transponders on the DWDM system. If problems arise on the composite side of the DWDM line system and there is limited management capability for the integrated transponder, troubleshooting may be impaired and require the drastic action of disconnecting the alien lambda from the system. Because of the lack of management capabilities for the alien lambda, this scenario can represent an insurmountable barrier, especially when these technical management attributes are considered alongside the likelihood of human interaction issues arising from the existence of two separate management groups for a customer. Juniper Networks Solutions Juniper has multiple approaches to long-haul and dark fiber applications based on standards for interoperability between optical vendors. For long-haul applications, Juniper can either use the native OC-768 SR interface connected to an external third-party OC-768 transponder, or the Type-4 4-port OC-192 PIC, which can be deployed with the inverse multiplexing capability of Junos OS, delivering the 40-Gbps capacity required. The four Juniper solutions discussed in this section are: External third-party transponder with OC-768 interface 4-port OC-192 PIC using inverse multiplexing into an OC-768 signal Dark fiber application with four fibers Dark fiber application with single fiber Figure 6 shows a configuration of an external third-party transponder with an OC-768 interface. Third-Party Transponder DWDM SYSTEM Lambdas Long Reach Transponders Composite Long-Reach Signal Management Multiplexer Figure 6: External third-party transponder: OC-768 approach 8 Copyright 2010, Juniper Networks, Inc.

9 Figure 7 shows this configuration with the 4-port OC-192 PIC. In this case, the transponder within the DWDM system can be used. DWDM SYSTEM Lambdas Short Reach Transponders Composite Long-Reach Signal With 4-Port OC-192 PIC Management Multiplexer Figure 7: 4-Port OC-192 approach This approach also works with dark fiber applications (Figure 8). Customers can use LR XFP optics to achieve the distance required. If it is necessary to use a single fiber pair, the four optical connections can be multiplexed together with an external passive optical multiplexer. Long-Reach XFP and Dark Fiber Long-Reach XFP Dark Fiber With 4-Port OC-192 PIC With 4-Port OC-192 PIC Multiplexer FOUR-FIBER SOLUTION SINGLE-FIBER SOLUTION Figure 8: Dark fiber application with four-fiber or single-fiber solution A common element in three of the Juniper solutions is the inverse multiplexing capability on the Type-4 4-port OC-192 card. This feature enables the four OC-192 interfaces to be treated by the packet forwarding engine as a single OC-768 connection. The SONET framing application-specific interface card (ASIC) designed by Juniper that is used on the PIC has this proprietary feature embedded. The feature sprays a packet across all four of the SONET links. Since this occurs at the byte level, there is no reordering issue, and the use of all four links is distributed uniformly, thereby presenting an optimal technical solution. The configuration of this option is simple. To configure OC-768 mode, enter the following: chassis { lcc # { fpc # { pic # { aggregate-ports; } } } } After this code is executed, the 4-port OC-192 PIC behaves like an OC-768 PIC. The OC-192 ports so-x/y/1-3 will disappear, and so-z/y/0 will be reported as an OC-768 port. Copyright 2010, Juniper Networks, Inc. 9

10 Economic Advantages of Juniper Solutions The key advantage of the 4-port OC-192 solution is the capability for a longer reach. DWDM XFP optics can reach to 80 km, and some third-party XFPs can reach to 110 km. Thus, amplification which is very expensive and tedious to maintain is not needed within the metro network. The 4-port OC-192 solution enables enterprises to lease only a single fiber when using with a passive multiplexer to aggregate the 10-Gbps channels into a single OC-768 stream. Without a passive multiplexer, a fiber would have to be leased independently for each DWDM or non-dwdm wavelength and routed separately through the metro network or between cities. This option has significant upside, however, in that it allows operators to leverage routing power to determine new paths to destination networks in the event of a topology change. Routers are inherently better at this than are lower-layer devices. Conclusion Juniper provides industry-leading integration of optical transport technologies into routers. To accommodate the flexible, remote provisioning requirements of optical networks, Juniper provides interfaces that incorporate DWDM and SONET technologies, including inverse multiplexing. Juniper also provides industry-leading GMPLS support, including GMPLS signaling for 40-Gbps interfaces. Juniper addresses the requirement to support 40-Gbps long-haul and dark fiber metro network opportunities using the solutions presented. Long-haul applications are supported through the use of an external 40-Gbps transponder from a third party or through deployment of four parallel interfaces to a DWDM line system. Dark fiber metro network opportunities are addressed using either a multiple-fiber or a single-fiber solution. For More Information For more information about the features and functions described in this document, see the data sheets and documentation listed here. Data Sheets The following data sheets are available by clicking the Modules tab at Tunable 10-Gigabit Ethernet DWDM PIC (PC-1XGE-DWDM-CBAND) 4-port OC-192 PIC (PD-4OC192-SON-XFP) Documentation for Tunable Juniper Networks 10-Gigabit Ethernet DWDM PIC Features More information about the tunable 10-Gigabit Ethernet DWDM PIC can be found at: About Juniper Networks Juniper Networks, Inc. is the leader in high-performance networking. Juniper offers a high-performance network infrastructure that creates a responsive and trusted environment for accelerating the deployment of services and applications over a single network. This fuels high-performance businesses. Additional information can be found at Corporate and Sales Headquarters APAC Headquarters EMEA Headquarters To purchase Juniper Networks solutions, Juniper Networks, Inc North Mathilda Avenue Sunnyvale, CA USA Phone: 888.JUNIPER ( ) or Fax: Juniper Networks (Hong Kong) 26/F, Cityplaza One 1111 King s Road Taikoo Shing, Hong Kong Phone: Fax: Juniper Networks Ireland Airside Business Park Swords, County Dublin, Ireland Phone: EMEA Sales: Fax: please contact your Juniper Networks representative at or authorized reseller. Copyright 2010 Juniper Networks, Inc. All rights reserved. Juniper Networks, the Juniper Networks logo, Junos, NetScreen, and ScreenOS are registered trademarks of Juniper Networks, Inc. in the United States and other countries. All other trademarks, service marks, registered marks, or registered service marks are the property of their respective owners. Juniper Networks assumes no responsibility for any inaccuracies in this document. Juniper Networks reserves the right to change, modify, transfer, or otherwise revise this publication without notice EN Mar 2010 Printed on recycled paper 10 Copyright 2010, Juniper Networks, Inc.