AMCC s Pemaquid device enables the cost-effective implementation of Metro-Ethernet for Optical-Based Metro and Long-Haul Transport Networks

Transcription

1 AMCC s Pemaquid device enables the cost-effective implementation of Metro-Ethernet for Optical-Based Metro and Long-Haul Transport Networks Mark Donovan (Senior PMM) and Keith Conroy (Sr. Solutions Architect) AMCC Corp, 200 Minuteman Road, Andover, MA mdonovan@amcc.com / ( ); kconroy@amcc.com (215) Abstract: The integration of OTN s FEC and EDC technologies into AMCC s Pemaquid 10GbE Mapper device offers the potential for greatly improving the cost-effective deployment of next generation data services and transport technologies such as metro/carrier Ethernet. 1. Ethernet s Dominance in the LAN migrates to the MAN/WAN For some time now Ethernet has been the protocol of choice in the enterprise, home, and mobile infrastructure for transporting Internet Protocol (IP) data, voice, and video over Local Area Networks (LAN). The main reasons for Ethernet dominating the LAN is its simplicity and low cost. Ethernet is a best effort protocol service for transporting traffic between computers, printers and other networking equipment in a local area network. It is architected to work in a shared environment where multiple network elements can be connected and communicate with each other over a single wire. Because of Ethernet s cost attractiveness, due to its larger ecosystem, a transformation is taking place in next generation Metro/Wide Area Networks (MAN/WAN). There has been interest in extending Ethernet directly over the (MAN/WAN). This interest has manifested itself over the past couple of years in the form of Carrier Grade Ethernet and Metro Ethernet services. As shown in Figure 1.0, this transformation is taking place from a multiple network layer (PSTN, FR, ATM, IP), using SONET/SDH as the transmission protocol over WDM networks, to a simplified IP/MPLS/Ethernet based service platform using Optical Transport Network (OTN) for transmission over Non-WDM or WDM optical networks. This transformation will yield a cost effective solution with high reliability and optical capacity. Figure 1.0 A New and Cost Effective Network Structure Ethernet Over Glass In the MAN/WAN, the SONET/SDH protocol has dominated. Traditionally, to bridge the gap between the LAN and WAN/MAN, ethernet frames carrying IP packets needed to be terminated/regenerated and the IP packets stuffed into/removed from ATM cells or Frame Relay Frames. The cells or frames would then be encapsulated into SONET/SDH frames prior to being transmitted over the MAN/WAN. Due to the bandwidth growth from the timeframe a new means of serial 10G transport was adopted, Wave Division Multiplexing (WDM). WDM 1

2 extended the bandwidth by using multiple wavelengths over a single fiber. The WAN consists of WDM, NON- WDM and Dense WDM (DWDM) networks. Terminating and regenerating ethernet frames to transmit IP packets over the WAN has proved to be an expensive endeavor. Though the SONET/SDH protocol offers extremely robust management, signaling, control, maintenance and protection services, it is extremely expensive from a cost per bit transmission standpoint. With new applications, particularly video and data applications, driving massive increases in internet traffic bandwidth, service providers and telecom and datacom OEMs have been under increasing pressure to provide lower cost/bit transmission services. Consequently, the interest in extending Ethernet directly over the MAN/WAN has become a major objective. However, achieving this objective is fraught with new technical challenges and in some cases compromises. The WAN / SONET/SDH environment is circuit based and is extremely reliable, whereas the LAN/ Ethernet environment is packet based and best effort reliable. The LAN / Ethernet environment has traditionally lacked the quality of service (QoS), protection, and management services found in the WAN SONET/SDH environment. In addition, the LAN environment has non deterministic latency issues that are relatively absent in the WAN environment. 2. Ethernet Standard Bodies working towards Carrier Ethernet Services for the MAN/WAN To address these concerns the Metro Ethernet Forum (MEF) and the IEEE802 standards organization have been working to provide a set of standards for Carrier Grade Ethernet services that offer many of the feature sets of SONET/SDH, but without the cost/bit transmission penalty. Key features include: QoS OAM&P (Operations, Administration, Maintenance, and Protection) o Performance monitoring and predictable performance o Localization of Faults (Isolate and troubleshoot problems) & defect detection and reporting o Network availability and Protection Though the work that the MEF and IEEE802 organizations have done is helpful in realizing the goal of making ethernet the protocol of choice both in the LAN and MAN/WAN, there are still technical issues that have yet to be resolved and that will not be achieved by just data management protocol changes only. One key issue involves the actual optical transport of ethernet frames directly over metro and long haul distances with multiple huts. When traditional WDM equipment is merged with ethernet equipment, optical noise and signal impairments become a significant problem in the transporting of ethernet frames directly over optical lambdas. Optical impairments that need to be addressed include: Chromatic Dispersion (CD) and Polarization Mode Dispersion (PMD) Low Optical Signal to Noise Ratio (OSNR), associated with EDFAs In order for a carrier ethernet network solution to be realized these optical impairments, as well as the OAM&P features that are standard in today s Service Level Agreements (SLAs), need to be addressed. 3. The use of OTN to Provide the OAM&P features of SONET over Metro Ethernet with FEC One ideal solution for providing carrier ethernet services, and that mitigates the optical impairments issue, as well as addresses the OAM&P requirements, is to employ the OTN framing structure around the ethernet frame, prior to transporting it over an optical link. The OTN framing structure [1], defined by the ITU in the ITU-G.872, G.709 and G.795 specifications includes Forward Error Correction (FEC) technology along with Electronic Dispersion Compensation (EDC) that can attenuate the optical impairments sufficiently to enable the ethernet traffic to be transported over metro and long haul optical distances. 2

3 In addition, the OTN framing structure is a narrowed down version of the SONET/SDH protocol that can enable a cost-effective deployment of next generation data services with many of the same QoS, management & protection services of SONET/SDH. OTN also has several advantages over SONET/SDH based transport services including: Forward Error Correction (FEC) 6 Levels of Tandem Connection Monitoring (TCM) and improved performance monitoring statistics Transparent Transport of Client Signals Large Optical capacity - Multiplexing of 2.5G tributaries up to 43 to 112Gbit/s Carrier Class Management - Fast restoration and automatic provisioning - OAM (Operation, Administration, Maintenance) provisioning for End to End Networking - Efficient control maintenance for operators providing localization of faults performance monitoring, Signal Fail / Signal Degrade PM, and section & trail protection. 3.1 Benefits of OTN Forward Error Correction The ITU standard allows for two kinds of FEC code used at the 7% channel expansion rate. The standard FEC code, or GFEC code for G.709 FEC code, gives you 6.2db of gain at BER. The other 7% overhead code is a strong FEC code as defined by the standard. AMCC's EFEC code (for Enhanced FEC) fits in this standard definition and provides 8.6 db of coding gain at BER A key benefit of OTN FEC is that it provides increased gain to an optical transmission line. This translates into fewer huts or sub-connections required between a source and destination address. MAN/WANs have Single Mode Fiber transmission spans which can range up to 640km and in some cases 1000km. In most of these spans electronic regeneration is not used. The spans are broken into multiple 70-80km links feeding into fiber huts which have Dispersion Compensated Fibers (DCF) to compensate / mitigate Chromatic Dispersion (CD), and Erbium Doped Fiber Amplifiers (EDFA) to amplify the optical signal before re-transmission. For a 640km span this equates to 8 fiber huts or sub connections. Degradation of the signal will occur through each hut due to optical noise from the EDFA. With GFEC operation the channel can be run at 8e-5 and decoded to With EFEC operation the channel could be run at 2.0e-3 and decoded to 10e-15. See Figure 2.0 below. Figure 2.0 Channel BER rate vs. Decoded BER rate for GFEC / EFEC operation 3

4 Shown below in Figure 3.0 is an example of a graph showing OSNR vs. BER for 80km link. The data was taken using a zero chirp modulator running at Gbit/s. The receiver side used an Avalanche Photo Diode (APD) with EDC circuitry. As shown in this graph, using GFEC would allow an OSNR link budget as low as 14dB. For Enhanced FEC (EFEC), the OSNR budget could go as low as 11dB. This is one of the key benefits of using OTN for transporting ethernet in a MAN/WAN. Without it, the OSNR link budget through multiple EFDA huts would need to stay above 23-24dB OSNR to achieve a 10e-12 BER. For fiber spans (>600km) which have PMD or additional optical noise, EFEC and EDC provide added margin in the link budget. 80km (10.709Gbit/s) EFEC Breaks down at BER =2e E E-03 GFEC Breaks down at BER =8e-5 80km 0km 1.00E E-05 BER 1.00E E E E-09 0km 80k 1.00E OSNR Figure 3.0 OSNR vs BER for 80km Link 3.2 Background and Benefits of OTN Tandem Connection Monitoring OTN Tandem Connection Monitoring (TCM) is another key benefit in the transmission of Ethernet traffic in the MAN/WAN. OTN TCM enables carrier s carrier services, where a Carrier A needs to continue to monitor a signal as it passes it through Carrier B s network. SONET/SDH provides one layer of TCM, where as the OTN G.709 standard provides 6 layers. SONET/SDH monitoring is broken down into Section, Line and Path monitoring. A problem arises with SONET/SDH when there is a Carrier s Carrier situation as shown below in Figure 4.0 [2], 4

5 Figure 4.0 Example of two different Carriers / Operators Here Operator A needs to have Operator B carry transport its signal. However, Operator A also needs a way of monitoring the signal as it passes through Operator B s network. This is what a Tandem connection is. It is a layer between Line Monitoring and Path Monitoring. SONET/SDH was modified to allow a single Tandem connection. G.709 allows six levels. SONET/SDH could never work in a transparent fashion in the above network. TCM1 is used by the User to monitor the Quality of Service (QoS) that they see. TCM2 is used by the first operator to monitor their end-to-end QoS. TCM3 is used by the various domains for Intra domain monitoring. Then TCM4 is used for protection monitoring by Operator B. There is no standard on which TCM is used by whom. The operators have to have an agreement, so that they don t conflict. 4. Realization of OTN Features into Next Generation Metro Ethernet Integrated Circuits and Equipment The realization of a solution that employs OTN, with FEC and Enhanced FEC functionality is relatively straight forward to implement. By front-ending an OTN framing function, with FEC or Enhanced FEC support, onto a traditional 10GbE physical layer integrated circuit, a metro ethernet platform, such as an edge switch router, could directly interface to an optical metro network. The integrated circuit could be architected to bolt seamlessly to a MAC, network processor, or switch fabric device. AMCC s Pemaquid device is the first device available to the marketplace that indeed provides this level of functionality and integration. The Pemaquid (S19258) represents AMCC s first device in its MEtrON (Metro Ethernet Optical Networks) product family that is designed for Metro Ethernet and Carrier Grade Ethernet solutions. Pemaquid, with its rich suite of integrated 10GbE to OTU2 Mapping modes, EDC, FEC, and XAUI and Serial 10G Interfaces is the perfect answer for enabling a cost-effective implementation of Metro-Ethernet for Optical-Based Metro and Long-Haul Transport Networks. Pemaquid enables the direct connection between 10G MACs and XFP/SFP+ Optical modules as seen in Figure 5.0 below. A single Pemaquid can take the place of up to three devices; a FEC/Framer/Mapper device, an SFI4.1 to Serial 10G Physical layer device and a bridge device to connect the 10G MAC to the FEC/FRAMER/Mapper device. 5

6 LINE 1 x OTU-2 (Up to 160km) 10G XFP Module Serial 10G XFI PEMAQUID 10G MAC/PCS with GFEC/EFEC XAUI 10G np or MAC LINE 1 x OTU-2 Up to 300KM Ethernet Based Uplink Switch Card or 300 Pin MSA Module SFI4.P1 S XFI 1 9 PEMAQUID 2 10G MAC/PCS 5 with GFEC/EFEC 0 XAUI Ethernet Switch Fabric Ethernet Based Uplink Switch Card Backplane Figure 5.0 Pemaquid in a Metro-Ethernet Chassis Line Card Application The Pemaquid is ideally suited for Metro-Ethernet Switch/Router and DWDM systems. It supports pure 10GbE LAN Metro-Ethernet networks, as well as WAN and OTN networks via its rich set of 10GbE over WAN and OTN mapping modes. With its integrated serial 10G PHY XFI/SFI interface and provisional G.709 GFEC/EFEC features, it provides a seamless interface to XFP and SFP+ optical modules. It is ideally suited for carrier grade metroethernet switch/router cards, OTU2 DWDM client tributary and line cards, and 10GbE / OC-192/STM-64 multiservice provisioning platform client tributary and line cards. Also, with its integrated FRACn synthesizer, a single low cost external oscillator is all that is required to enable Pemaquid to support 10G line rates from 9.954Gbps up to 11.32Gbps, while meeting SONET/SDH and OTN jitter requirements (See Figure 6.0 below). Pemaquid also supports loop timing for SONET/SDH, OTH, and Synchronous Ethernet applications. See Figure 6.0 for a table listing showing Pemaquid s various recovered clock options. Figure 6.0 Pemaquid s FRAC N enables one low Cost Reference Clock to Support all LAN/WAN Baud Rates 6

7 In addition to this timing flexibility, the Pemaquid device supports seven 10GbE mapping modes, including: Bit Transparent Mapping, GFP mapping, WIS framing, and 10GbE LAN pass-thru mode. 4.1 Synchronous Ethernet Critical for Traditional TDM Voice Services and Mobile Services It is imperative that Carrier ethernet equipment support Synchronous Ethernet. Synchronous Ethernet is necessary for enabling the support of legacy TDM services, such as T1/E1 voice traffic, as well as mobile cell services. Synchronous ethernet allows important timing information to be persevered in the Metro Ethernet network. This timing information is critical for ensuring clean TDM voice services and preventing dropped calls. The ability to support loop timing (bits timing) is a fundamental requirement of Synchronous Ethernet. As mentioned above, Pemaquid supports Synchronous Ethernet applications by providing a demapped clock signal from the Line receive OTN signal. This demapped clock signal represents the native 10Gb Ethernet clock signal that was transmitted over the Line OTN interface. This clock signal can then be used to feed a common Timing card that can generate a TX Reference clock to feed both the Receive System Interface and the Line Transmit Interface, effectively providing loop timing based on the received native 10Gb Ethernet signal. See Figure 7.0 below. Line Card Pemaquid f2 f1 MUX FRAC N ETHERNET SWITCH 10GE MAC 3.125G f2 XAUI XAUI 8b/10b Deskew Output Monitor MUX f1 8b/10b Encoder Bit Transparent Async Mapping OTN Demapping RX_DEMAP_CLK See Below in Table G.709 OH Insert GFEC EFEC Decoder G.709 OH Monitor GFEC EFEC Encoder G.709 Framer XFI XFI RX_MCLK 1/16 1/64 LINE RATE f1 or f2 f2 OTN Network G G G MHz f2-8khz Integer Timing Card Figure 7.0 Pemaquid in a Synchronous Ethernet over OTN application Finally, with integrated ITU G.709 FEC, and AMCC s Enhanced FEC (ITU G I4), Pemaquid enables Metro and Long Haul transmission of 10GbE over OTN networks in low OSNR environments with optical impairments such as chromatic dispersion and polarization mode dispersion. In addition, the GFEC and Enhanced FEC, also compensates for nonlinear inter-channel impairments such as cross-phase modulation (XPM) and four-wave mixing (FWM), which allows for a narrow channel spacing of 25Ghz for DWDM systems. Though feature rich with its 10GbE mappings, framing, FEC, and integrated 10G Phy, the Pemaquid is available in a small 19x19 package and only consumes 2.5 watts under typical applications. 7

8 5. The MEtrON product family leverages AMCC Rubicon family to enable the convergence of Metro Ethernet and OTN services AMCC s Pemaquid device represents the first device in AMCC s MEtrON product family that specifically targets Metro Ethernet and Carrier Grade Ethernet solutions. The MEtrON family spawns from AMCC s highly successful Rubicon product family. The Rubicon product family consists of a number of highly integrated 10G and 2.5G Framer/Mapper devices with integrated G.709 FEC, AMCC s Enhanced FEC (EFEC), and Electronic Dispersion Compensation (EDC) features. These devices were targeted towards traditional TDM and OTN applications and achieved market dominance due to their 10GbE to SONET/SDH and OTN mapping capabilities. The MEtrON product family leverages the Rubicon 10GbE mapping, GFEC, EFEC, and EDC technologies by integrating them into single device solutions. In addition, these single device solutions also integrate Telecom class performance 10G SERDES, and traditional system interfaces, such as the XAUI protocol, to seamlessly connect to 10G MACs, Network Processors, and Ethernet Switch devices. The result of this silicon integration is a new AMCC product family (MEtrON) that enables highly integrated physical layer solutions for Carrier Ethernet platforms requiring direct connection to OTN and WAN networks. The Pemaquid device, along with future MetrON product offerings, enables extremely cost effective 10G Framer/Mapper/Phy solutions that require minimum power and footprint. 6. Conclusion By employing OTN with FEC and EDC technology into next generation metro ethernet equipment, large CAPEX and OPEX cost savings can be realized. Besides the cost per bit transmission savings by maintaining ethernet throughout the LAN/MAN/WAN infrastructure, edge WDM equipment could outright be eliminated in many cases, as future Metro Ethernet boxes could connect directly to metro and long haul WDM networks. In addition, fewer huts are required for transporting Ethernet over metro or long haul networks saving both equipment and maintenance costs. The integration of OTN s FEC and EDC technologies into AMCC s Pemaquid 10GbE Mapper device offers the potential for greatly improving the cost-effective deployment of next generation data services and transport technologies such as metro/carrier Ethernet OTN is the cost-effective solution for implementing metro ethernet over optical based networks. 7. References [1] Optical Transport Network (OTN) ITU Recommendation Telecommunication, G.982 and G.709, ITU 2001 [2] T. Walker; "OTN Tutorial", Presented to ITU Study Group 15, ITU