Copy of presentation given to IEEE 802.3z September 1996 Interim Meeting in Coeur d'Alene, Idaho. (This file should be printed using a fixed-width font, like COURIER) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Optics Update to Joint Proposal of May, 1995 by Del Hanson, Jonathan Thatcher, Stan Swirhun o Overview of approach o Applications coverage o Details (white paper) The following companies have indicated their support for the concepts outlined in this proposal (in alphabetical order): HP IBM Vixel Optical Adapter Architecture _____________________________ We assume use of the same architecture as presented by Johnson, "Architectural Overview". This presentation focuses on the PMA and PMD sublayers, for 8B10B-coded optics. PMA Layer: Serializer _____________________ Assumes 8B10B coding is done by PCS layer Uses same 8B10B PMA Layer for all optical devices > PMA service interface is 10-bit interface specification @ 125 MHz > Use style of jitter specification per ANSI Jitter Study Group > Scale interface timing for 125 MHz operation Interface to PMD is serial PECL PMD Layer: Two Transceivers ___________________________ (1) Short-wavelength laser (SWL) Multimode fiber: Lowest-cost option that easily covers horizontal desktop distances, and some building backbone distances, on either 50 or 62.5 um MMF (per ISO 11801) (2) Long-wavelength laser (LWL) Single mode fiber: Goes at least 2 km on SMF Multimode fiber: Extends reach on MMF to longer building backbone distances Application Coverage ____________________ LWL on SMF: from zero to 2km (good for campus backbones) LWL on 50 um MMF: from zero to somewhere in excess of 500m LWL on 62.5 um MMF: from zero to somewhere in excess of 500m (extends distance on building backbones) SWL on 50 um MMF: from zero to as much as 500m SWL on 62.5 um MMF: from zero to as much as 200m (good for desktops, horizontal connections) This plan meets or exceeds study group objectives > It is based on available parts > It is not dependent on controlled mode launch assumptions > Each transceiver will be characterized over its full operating range on each type of fiber Details: Our White Paper ________________________ This white paper contains detailed notes concerning the following modules. It is not intended to be a complete specification. It indicates the state of our thinking to date. > 8B10B PMA sublayer > 8B10B PMD sublayer: SWL optics > 8B10B PMD sublayer: LWL optics 8B10B PMA SUBLAYER Table--Data Rate Specifications Description Unit Value Unencoded Serial Bit Rate Mbaud 1000 Encoded Serial Bit Rate Mbaud 1250 Baud Rate Tolerance PPM 100 This section should include jitter budget allocations. It will be a scaled Version of the ANSI Fibre Channel 10b Specification. 8B10B PMD SUBLAYER: SWL OPTICS Table--Operating Distance for Each Fiber Type (meters) Optical Source 62.5 micron MMF 50 micron MMF SMF Shortwave Laser 200 450 N/A LASER SAFETY Optical transceivers shall be Class 1 laser certified under any condition of operation. This includes single fault conditions whether coupled into a fiber or out an open bore. Certification shall include both CDRH and IEC 825.... All laser safety standards and regulations require that the manufacturer of a laser product provide information about the product's laser, safety features, labeling, use, maintenance and service. This documentation must explicitly define requirements and usage restrictions on the host system necessary to meet these safety certifications. A host system that fails to meet these requirements and/or usage restrictions may emit laser radiation in excess of the safety limits of one or more safety standards. In such a case, the host manufacturer is required to obtain its own laser safety certification. BIT ERROR RATIO OBJECTIVE The SWL optical link shall not exceed a 10E-12 bit error ratio during the links lifetime under any normal operating conditions, including: worst case temperature, transmitter, cable plants, and receivers. This specification will more than meet our 802 functional requirements. 8B/10B ENCODING 8B/10B Encoding provides a balanced, DC, bit stream with a maximum run length of 5. It is the basis for many simplifications made in the high speed optical and electrical design, and it is required for the correct operation of this PMD. SWL TRANSMITTER The general laser transmitter pulse shape characteristics are specified in the form of a mask of the transmitter eye diagram (see Figure 1:).These characteristics include optical rise time, fall time, overshoot, undershoot and ringing.... The mask of the eye shall be measured using a fourth-order Bessel Thompson transfer function to provide uniform measurement conditions (it is not expected to match the filter characteristics of a typical receiver).... The laser shall have properties which significantly reduce noise problems (especially modal noise) associated with using lasers on multimode fiber. ***SOME Measurement(s)*** shall be measured using the methods specified by the "Modal Noise Test Methodology Group." If the laser is a self- pulsating type, the self pulsation frequency shall be greater than three times the bit rate to allow for efficient filtering at the receiver. Deterministic and Random Jitter shall be measured using the methods specified by the "Fibre Channel Jitter Study Group." Extinction ratio shall be measured using the methods specified inOFSTP-4. This measurement may be made with the node transmitting any valid 8b/10b data stream. The minimum value of the extinction ratio shall be the minimum acceptable value of the ratio (in dB) of the average optical energy in a logic-one to the average optical energy in a logic-zero. The extinction ratio shall be measured under fully modulated conditions with worst case reflections. Optical power shall be measured using the methods specified in OFSTP-2.This measurement may be made with the node transmitting any valid 8b/10bdata stream. Figure 1 Transmitter Eye Mask Definition . (to be taken from Fibre Channel) Table SWL transmit characteristics Description Unit Value Status Bit Rate Mbaud/s 1250 +/- 100 agreed ppm Transmitter laser agreed type Wavelength nm 770-860 agreed Spectral width nm, RMS 4 see note 1 Max. launch dBm, avg. -5 agreed power @770 nm Max. launch dBm, avg. -4 agreed power @ 860 nm Min. launch dBm, avg. -10 agreed power Extinction dB 9 ? ratio RIN (max) dB/Hz -117 see note 2 Eye opening see note 3 Note 1: We need to reconcile the use of RMS units in the SWL transmit table with the use of FWHM units in the LSL transmit table. Note 2: Regarding relative intensity Noise (RIN), it is a known effect that reflections can increase RIN The ISO/IEC 11801 and TIA/EIA 568A Standards do not specify the return loss for multimode connectors. Building premises cabling can have multiple non physical contact connections; each of which can cause reflections of 8dB (worst case). Vixel will test the 4 different manufacturers' lasers for the effects of reflections on the laser RIN. These tests are expected to be completed before October of 1996. The RIN numbers for SWL and LWL have yet to be reconciled. Note 3: We have tentatively agreed that it is sufficient to specify the transmit eye mask in a way that allows the implementor to trade-off rise-time, fall-time and jitter. SWL RECEIVER Table SWL receive Description Unit Value Status Minimum receive dBm, avg. -17 agreed power Maximum dBm, avg. ? (see note receiver power 2) BER per baud 1E-12 agreed (see note 3) Return loss dB, min 12 (more work required) Optical ns ? (more rise/fall work assumed for required, these see note measurements 3) Note 1: HP would like to see the maximum receiver power match the maximum launch power. IBM would like to see the maximum receiver power match other standards. The outcome of this issue depends on projected future changes in PDRH and EIA 825-1 laser power safety limits. Note 2: FC is "looking" at the problem of having all subcomponents specified to 1E-12 BER while having the entire link also specified as 1E-12 BER. The IEEE functional requirements are more relaxed than 1E-12. Note 3: We have tentatively agreed that it is sufficient to specify the transmit eye mask in a way that allows the implementor to trade-off rise-time, fall-time and jitter. General note: We need to specify a worst-case received eye signal for the purpose of testing clock recovery systems. If the fibre-channel jitter study group completes its work in time, we may use their ideas on how to do this. SWL MEDIA Table Media characteristics for use with SWL Description Unit Value Status 62.5 um 50 um MMF SMF MMF Guaranteed m 200 450 n/a operating distance Max. dB/km 4 3.5 n/a (needs attenuation @850 work) nm Min. modal MHZ*km 160 400 n/a (needs bandwidth @850 work) (overfilled nm launch) at 850 nm Dispersion ps/km* 0.093 0.105 n/a (note slope nm2 1) Min. um 1.36 1.33 n/a (note dispersion 1) point Note 1: HP has submitted these figures for consideration. IBM is reviewing them. Note: The optical fiber interface shall be the Duplex SC and shall meet the dimension and interface specifications of IEC 874-14. The connector shall meet the performance specifications as specified in ISO/IEC 11801. It is recommended that the network polarity (transmit and receive) be managed in accordance with ANSI/TIA/EIA-568-A. Note: Physical contact (PC) connectors shall be used throughout the link. 8B10B PMD SUBLAYER: LWL OPTICS Table Operating Distance for Each Fiber Type (meters) Optical source 62.5 micron MMF 50 micron MMF SMF Longwave Laser > 550 (perhaps > 550 (perhaps 2,000 (or as much as as much as more) 850m) 850m) LASER SAFETY Optical transceivers shall be Class 1 laser certified under any condition of operation. This includes single fault conditions whether coupled into a fiber or out an open bore. Certification shall include both CDRH and IEC 825.... All laser safety standards and regulations require that the manufacturer of a laser product provide information about the product's laser, safety features, labeling, use, maintenance and service. This documentation must explicitly define requirements and usage restrictions on the host system necessary to meet these safety certifications. A host system that fails to meet these requirements and/or usage restrictions may emit laser radiation in excess of the safety limits of one or more safety standards. In such a case, the host manufacturer is required to obtain its own laser safety certification. BIT ERROR RATIO OBJECTIVE The LWL optical link shall not exceed a 10E-12 bit error ratio during the link's lifetime under any normal operating conditions, including: worst case temperature, transmitter, cable plants, and receivers. This specification will more than meet our 802 functional requirements. 8B/10B ENCODING 8B/10B Encoding provides a balanced, DC, bit stream with a maximum run length of 5. It is the basis for many simplifications made in the high speed optical and electrical design, and it is required for the correct operation of this PMD. LWL TRANSMITTER The general laser transmitter pulse shape characteristics are specified in the form of a mask of the transmitter eye diagram (see Figure 1:). These characteristics include optical rise time, fall time, overshoot, undershoot and ringing.... The mask of the eye shall be measured using a fourth-order Bessel Thompson transfer function to provide uniform measurement conditions (it is not expected to match the filter characteristics of a typical receiver).... The laser shall have properties which significantly reduce Deterministic and Random Jitter shall be measured using the methods specified by the "Fibre Channel Jitter Study Group." Extinction ratio shall be measured using the methods specified in OFSTP-4. This measurement may be made with the node transmitting any valid 8b/10b data stream. The minimum value of the extinction ratio shall be the minimum acceptable value of the ratio (in dB) of the average optical energy in a logic-one to the average optical energy in a logic-zero. The extinction ratio shall be measured under fully modulated conditions with worst case reflections. Optical power shall be measured using the methods specified in OFSTP-2. This measurement may be made with the node transmitting any valid 8b/10b data stream. Figure Transmitter Eye Mask Definition . (to be taken from Fibre Channel) Table LWL transmit characteristics Description Unit Value Status Bit Rate Mbaud/s 1250 +/- 100 agreed ppm Transmitter laser agreed type Wavelength nm 1270-1355 agreed Spectral width nm, FWHM 14 note 1 Max. launch dBm, avg. -3 agreed power Min. launch dBm, avg. -13 note 2 power Extinction dB 9 ? ratio RIN (max) dB/Hz -116 ? see note 3 Eye opening see note 4 Note 1: We need to reconcile the use of RMS units in the SWL transmit table with the use of FWHM units in the LSL transmit table. Note 2: HP has submitted this figure for consideration. IBM is reviewing it. Note 3: Regarding relative intensity Noise (RIN), it is a known effect that reflections can increase RIN The ISO/IEC 11801 and TIA/EIA 568A Standards do not specify the return loss for multimode connectors. Building premises cabling can have multiple non physical contact conections; each of which can cause reflections of 8dB (worst case). Vixel will test the 4 different manufacturers' lasers for the effects of reflections on the laser RIN. These tests are expected to be completed before October of 1996. The RIN numbers for SWL and LWL have yet to be reconciled. Note 4: We have tentatively agreed that it is sufficient to specify the transmit eye mask in a way that allows the implementor to make trade-offs regarding rise-time, fall- time and jitter. LWL RECEIVER Table LWL receive characteristics Description Unit Value Status Minimum receive dBm, avg. -20 power Maximum dBm, avg. -3 agreed receiver power BER per baud 1E-12 agreed (see note 2) Return loss dB, min 12 (more work required) Optical ns ? (more rise/fall work assumed for required, these see note measurements 3) Note 2: FC is "looking" at the problem of having all subcomponents specified to 1E-12 BER while having the entire link also specified as 1E-12 BER. The IEEE functional requirements are more relaxed than 1E-12. Note 3: We have tentatively agreed that it is sufficient to specify the transmit eye mask in a way that allows the implementor to make trade-offs regarding rise-time, fall- time and jitter. General note: We need to specify a worst-case received eye signal for the purpose of testing clock recovery systems. If the fibre-channel jitter study group completes its work in time, we may use their ideas on how to do this. LWL MEDIA Table Media characteristics for use with LWL Description Unit Value Status 62.5 50 um MMF SMF um MMF Guaranteed m 550-850 550-850 2000+ T.B.D. operating note 1 distance Max. dB/km 1 1 < 1 note 1 attenuation @1300 (needs nm work) Min. modal MHZ*km 500 500 n/a (needs bandwidth @1300 work: (overfilled nm at 500 launch) MHz-km (see note 2) you can get 850m on 50 um) Dispersion ps/km* 0.093 0.105 note 1 slope nm2 Min. um 1.36 1.33 note 1 dispersion point Dispersion ps/nm, 12 note 1 (up to max. RMS distance) Note 1: HP has submitted these figures for consideration. IBM is reviewing them. Note 2: For MMF, Measured in accordance with IEC 793-1-C2A (ANSI/TIA/EIA-455-51A) or IEC 793-1-C2B (ANSI/TIA/EIA-455-30B). Note: For MMF, a portion of the system power penalty is reserved for performance degradation due to modal noise. A methodology for the measurement of modal noise is being defined by the TIA FO-2.2 committee. The system power penalty due to modal noise shall not exceed 1.0 dB for 62.5 um fiber and 1.5 dB for 50 um fiber. The modal noise system power penalty above assumes that the connector loss is distributed across the link and that the maximum connector loss for any single connector does not exceed 0.75 dB. Note: A 7 dB system budget is specified. For 62.5 fiber, the 7 dB budget supports 5 dB allocated for cable plant losses and 2 dB for the system power penalty. For 50 fiber, the 7 dB budget supports 4.5 dB allocated for cable plant losses and 2.5 dB for the system power penalty. For SMF, there is no modal noise penalty and there is only a 1 dB penalty for chromatic dispersion, leaving a 6 dB budget for cable plant losses. Note: The optical fiber interface shall be the Duplex SC and shall meet the dimension and interface specifications of IEC 874-14. The connector shall meet the performance specifications as specified in ISO/IEC 11801. It is recommended that the network polarity (transmit and receive) be managed in accordance with ANSI/TIA/EIA-568-A. Note: Physical contact (PC) connectors shall be used throughout the link.