CAPACITY UPGRADE THROUGH 40G

Transcription

1 Application August 2009 About ADVA Optical Networking ADVA Optical Networking (FSE: ADV) is a global provider of telecommunications equipment. With innovative Optical+Ethernet transport solutions, we build the foundation for high-speed, nextgeneration networks. Our FSP product family adds scalability and intelligence to our customers networks while removing complexity and cost. With a flexible and fastmoving organization, we forge close partnerships with our customers to meet the growing demand for data, storage, voice and video services. Thanks to reliable performance for more than 15 years, we have become a trusted partner for more than 200 carriers and 10,000 enterprises across the globe. For more information, please visit us at CAPACITY UPGRADE THROUGH 40G The rapid growth in bandwidth consumption is straining networks everywhere. Currently, WDM transport networks are facing bandwidth exhaustion as 10G channel plans fill up. With 100GE still in its early stages, bandwidth providers are turning to 40G transport solutions to instantly quadruple their remaining 10G channel. This application white paper describes how our existing customers are quickly and easily upgrading their existing 10G WDM transport networks to 40G using muxponder technology that is shipping today. Table of contents: 1. The need for 40G transport 2 2. The muxponding solution 2 3. Investment protection 3 4. ADVA Optical Networking product 4 5. Example network upgrade 4 6. Looking ahead 5 Authors: Jim Theodoras and Clark Scott ADVA Optical Networking ADVA Optical Networking August All rights reserved. Legal disclaimer: The information provided in this document is distributed as is without any warranty, either express or limited.

2 1. The need for 40G transport Across the globe, bandwidth consumption continues to explode. There seems to be an endless stream of new applications that consume greater amounts of bandwidth: Peer-to-peer sharing, social networking, cloud computing, digital photo storage and exchange, video messaging, the PDA revolution, the list goes on and on. In the past, transport networks have attempted to keep up with this data growth by simply adding more 10Gbit/s channels (colors) to their existing Dense Wavelength Division Multiplexing (DWDM) networks. However, recently this strategy has run out of steam, as existing channel plans have filled up. CO or DC 10Gbit/s transponders Optical lineshelf MUX Wavelength exhaustion Figure 1: Wavelength exhaustion In response to this predicament, multiple standards bodies launched efforts to develop 100Gbit/s protocols and technology. 100Git/s technology has been successfully field trialed, and early 100GbE prototypes are just beginning to ship in limited volume. However, due to the relentless growth in data traffic, many transport links face bandwidth exhaustion today. The problem exists now, and a real solution is needed today. 40Gbit/s muxponding technology and products are the solution, and are shipping today. 2. The muxponding solution 40Gbit/s is typically thought of as a core backbone overbuild network, as that was one of its earliest applications. Nevertheless, this perception can be a bit misleading, as 40Gbit/s is also a quick and easy way of relieving congestion on existing 10G DWDM networks. The key technology that makes both applications possible is muxponding. Muxponding is a Portmanteau word that combines multiplexer (nicknamed a Mux) and transponder. Multiplexer refers to the fact that four streams of 10Gbit/s are combined into a single 40Gbit/s stream and then separated out again. Transponder refers to the fact that the 40Gbit/s information stream is put onto a standards compliant DWDM optical channel that may be launched onto and received from an optical fiber. Figure 2: Functional block diagram Figure 2 shows a functional block diagram of a 4 x 10Gbit/s to 40Gbit/s muxponder. A muxponder is typically a self-contained linecard that plugs into a DWDM transport chassis. Note that all traffic enters and exits the linecard, so it does not need to hit the backplane, and no switching plane is needed. The client interfaces are 10Gbit/s, of various protocols, and in this case consist of pluggable optics. The line interface is 40Gbit/s, and fully tunable over the channel plan. The combination of pluggable client interfaces and tunable line interface greatly enhances the flexibility of the muxponder. The beauty of a muxponder solution lies in the ease in which existing transport networks can be upgraded. As shown in Figure 3, all that is needed is to simply connect the auxiliary router/switch ports to the client ports of a muxponder, and the line output of the muxponder to an unused channel on the DWDM combiner/splitter. If no unused channels are available, a single 10Gbit/s wavelength channel can be disconnected and replaced with a 40G wavelength channel, thus yielding three additional unused 10G channels. And that is it! No forklift upgrades, no router/switch upgrades, no re-engineering the network needed. CO or DC 10Gbit/s transponders 40Gbit/s muxponders spare Optical lineshelf MUX Figure 3: Muxponders give new life to networks 2

3 3. Investment protection Given the scenario of wavelength exhaustion, let s look at the options available. The first option that comes to mind is to simply replace the existing 10G linecards in the router/switch with 40G linecards. However, upon closer examination, this option has many drawbacks. 40G linecards in routers/switches are very expensive, running into seven-digit US/Euro territory. These linecards route traffic to the backplane and switching fabric, thus often requiring upgraded switch cards as well. In the end, you might as well replace the entire router chassis with something new. Not only is the new router expensive, but the existing 10G router linecards and switch fabric are no longer being used, and the existing network has been substantially disturbed during the upgrade process. The original problem was wavelength exhaustion, so why try to fix it in the router/switch? A second option is to install a new 40G core overlay network. There is no shortage of new DWDM platforms boasting 40G capabilities. Shiny new products can be tempting, but again, digging deeper reveals this may be overkill for dealing with wavelength exhaustion. Many vendors 40G transponders are expensive, and often require new amplifiers as well. The existing networks will need to be re-architected, with new span design rules, and new active re-generation sites chosen, often with closer spacing. The new 40G transponders may also force the upgrade to 40G client interfaces on the router/switches that feed the transport equipment. The older 10G client router/switch linecards and 10G transport transponders go unused, and must be either recycled elsewhere in the network, or written off. (Note that ADVA Optical Networking s 40G transceiver does not suffer these limitations, as it has been expressly designed to avoid the aforementioned pitfalls). Router Switch L Band: nm C Band: nm S Band: nm Figure 4: DWDM channel bands Router Switch Well, if wavelengths are the issue, why not simply add more wavelengths? There are two primary ways of increasing wavelengths, adding more bands and decreasing channel spacing. Most DWDM transport networks run in the C-band, which consists of 80 color channels spaced 50GHz apart. As shown in Figure 4, moving to the L- or S-band frees up more channels. However, the L- and S-band often have different span budgets, requiring revamping of existing active sites. The S-band is outside the range of traditional optical amplifiers, requiring new amplifiers. Moreover, these technologies tend to be proprietary to specific vendors. Decreasing channel spacing does indeed yield more available colors, yet suffers from some of the same disadvantages as moving to new bands. Squeezing channels too closely together changes the link budgets, forcing re-engineering of spans, and alters active re-generation spacing. Amplifiers will at a minimum need their gain adjusted, or even replaced. Channel spacings less than 50GHz tend to be proprietary and vendor specific. A properly designed muxponding solution has all the advantages, and possesses none of the disadvantages of the aforementioned options. The biggest advantage is, as all of the existing network gear remains in-service. There is no need to re-shuffle network gear or disturb revenue generating traffic. Existing optical combiner/splitters and amplifiers can be used as-is. There is no need to mess with the active sites or their spacing, as existing span budgets are maintained. Existing router/switch interface linecards can be used, with no need to upgrade their associated switching matrix. Moreover, in addition to protecting existing equipment, very little additional equipment is needed, as only one muxponder linecard is needed for every four additional 10G channels that are desired. The outcome of this comparison is summarized in Table 1 below: OPT DESCRIPTION COMMENT Upgrade router linecards to 40G Build a 40G overlay network Add L- or S-bands to existing C-band. Decrease channel spacing to <50GHz Install 40G Muxponders Expensive, poor Expensive, new span design rules, forces router upgrades, poor New span rules, new amplifiers and filters, expensive, poor New span rules, new amplifiers, poor Maximum investment protection over existing 10G DWDM networks Table 1: Comparison of upgrades 3

4 4. ADVA Optical Networking product Now that we have established muxponders are one of the best ways to simply, quickly, and cost-effectively upgrade an existing revenue generating network, let s take a closer look at ADVA Optical Networking s solution. In order to be able to capitalize on all of the advantages of a muxponder solution, the muxponder must be properly designed. For example, some 40Gbit/s muxponders on the market simply squeeze 4 x 10 Gbit/s data streams into a single channel slot using closely coupled filters, and this approach will have the same disadvantages as decreasing overall channel spacing to generate additional channels. ADVA Optical Networking s 40 Gbit/s muxponder, the 4TCC-PCTN-10GU+40G (hereafter referred to as 4TCC-40G) is a true 40 Gbit/s muxponder in that it multiplexes 4 x 10 Gbit/s data streams onto a G.709 standards compliant 40 Gbit/s serial wavelength. Key to the value proposition of muxponders is client flexibility. The 10 Gbit/s clients to be multiplexed will not necessarily all be 10 Gigabit Ethernet. The 4TCC- 40G can accept a wide variety of client traffic, and is able to multiplex a mix of: STM-64/OC-192, 10GbE WAN-PHY, 10GbE LAN-PHY OTU-2 The 10GbE LAN-PHY support features PCS layer termination, achieving 100% data throughput without overclocking! Client optics are front panel pluggable XFP form factor. Also key to the value proposition of muxponders is the line side interface. In order to maximize, the 40Gbit/s performance must match the existing 10Gbit/s channels as closely as possible. The 4TCC- 40G impresses here as well, having implemented a binary Phase Shift Keying (PSK) modulation scheme that is very tolerant of multiple passes through ROADM-based add/drop nodes in a DWDM transport network. In addition, this modulation scheme has very low Optical Signal to Noise Ratio (OSNR) requirements, which makes it perfectly suitable for links that have been engineered for traditional 10G technology. Furthermore, the 4TCC-40G has built-in tunable dispersion compensation on a per 50GHz channel basis that enables the adjustments needed to match a pre-existing span s budget. Finally, wavelength tunability is a must in order to take advantage of whatever color channels happen to be available, and the 4TCC-40G is tunable across the entire C-band, supporting all 80 channels at 50GHz spacing. 5. Example network upgrade In order to demonstrate just how straightforward a network upgrade through 40G is using ADVA Optical Networking s 4TCC-40G, let s walk through the following example: Assume a pre-existing DWDM network with 80 channels of 10Gbit/s spaced at 50GHz intervals, for a total of 800Gbit/s. The network spans between two cities over 1200km apart with no regeneration available in between. In other words, there are only optical amplifiers and ROADM based add/drop nodes in between the source and destination. While amplifier spacing and span budgets vary on a link by link basis, they average out to roughly 15 spans of 80km, each with a 24dB budget. For argument sake, let s assume the network is built with another vendor s DWDM equipment, and not ADVA Optical Networking. City A 80 channels of 10GE traffic on 50GHz grid 15 spans of 80km with 24dB link budget 80km 24dB 80km 24dB Site 1 Site 2 Site 15 Figure 5: Example network City B While this fairly typical scenario is not that challenging for modern DWDM technology, the difficulty arises when runs out. Suddenly, the span budgets that were not an issue at 10Gbit/s become challenging at 40Gbit/s. The incumbent vendor might not have a suitable 40G transponder or muxponder available, or if he does, it may not be compatible with the existing span budget. ADVA Optical Networking s 40G muxponding technology turns what could be a nightmare scenario into a simple and straightforward upgrade. 4

5 Mxpdr shelves Upgraded channels Legacy Added Total G G G 160G 920G G 320G 1040G G 640G 1280G G 1280G 1760G G 2560G 2720G G 3200G Table 2: Capacity upgrade options for 80 channel, 10GE network using 4TCC-40G One or more of the alternate vendor s line side cables (wavelengths) are disconnected from the combiner/ splitter and replaced with line side cable of the 4TCC- 40G. The existing 10G client cable is plugged into one of the client ports on the 4TCC-40G, making three more client ports still left available for additional bandwidth. This same procedure can be repeated as additional is needed until all the 10G wavelengths have been replaced with 40G wavelengths. Table 2 details possible upgrades. Qty Part number Description FSP 3000 chassis and commons Network element control unit 40Gbit/s muxponder linecard XFP, G, SR, 1310nm Table 3: Order list to upgrade four 10Gbit/s channels to 40Gbit/s, providing 120Gbit/s additional While the above example was hypothetical, it is important to note that ADVA Optical Networking has already upgraded the of many existing 10G networks across the globe using this approach. In many cases, the original networks were built using other vendors DWDM transport hardware. These networks were upgraded through 40G with no disruption to the existing revenue generating 10G traffic and are successfully carrying live traffic today, some over 1600km with no regeneration. 6. Looking ahead ADVA Optical Networking is at the forefront of 40G muxponder technology with best in class features such as universal client support, full data rate without overclocking, built in tunable dispersion compensation, and adaptive binary PSK modulation. We are not resting on our laurels, though. In order to bring bandwidth relief and upgrades to even more existing transport networks, ADVA Optical Networking continues to enhance the performance of our 40G muxponders ultimately yielding up to 40% more unregenerated distance. Figure 6: 4TCC-40G in FSP 3000 chassis Let s delve further into what is actually needed to upgrade four wavelength channels from 10Gbit/s to 40Gbit/s, thus adding 120Gbit/s more. The 4TCC-40G linecard is compatible with the standard FSP 3000 chassis, which can hold four of the 4TCC- 40G muxponders. Thus, only a single shelf will be needed for a four-channel, 120G upgrade. All that needs to be ordered is a chassis, network element, four 4TCC-40G muxponder linecards, and XFPs for the client ports. And the XFPs can be purchased and installed as additional is needed. The actual order list is shown in Table 3. 5