Fiber Bandwidth Requirements
			   for
		    802.3 Gigabit Ethernet


Steven E. Swanson
Corning Incorporated
607-974-4252
607-974-4941 FAX
swanson_se@corning.com

1. Introduction

This is a followup to my presentation in Wakefield on fiber   
bandwidth requirements. This presentation takes a high level view   
of the requirements and the proposed solutions for providing   
gigabit Ethernet links over multimode fiber.

Corning's objective is to meet the requirements of 802.3z gigabit   
Ethernet with a solution or solution set that meets the   
requirements, is robust, and represents the low cost system   
solution.

Corning will support the embedded base of fiber to the maximum   
extent possible. The first step in that process is to   
understand/characterize the embedded base.

Corning is not advocating replacing the entire embedded base of   
62.5 um fiber with 50 um fiber. However, 50 =B5m fiber is the   
preferred cable plant for short wavelength Fibre Channel   
solutions for a reason - it is a better solution for supporting   
short wavelength high speed applications.   

Finally, Corning can support most of proposals that you'll hear   
today. Each solution, however, offers tradeoffs that we need to   
fully understand before excluding any solution set.

2. Overview
	- Recap of key observations from Wakefield meeting
	- Link length analysis for all sources using 160, 400,   
	  and 500 MHz.km fiber
	- Proposed goals
	- Optical LAN paradigms
	- Understanding the embedded base
	- Supporting the embedded base
	- The case for 50 um fiber   
	- Summary
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3. Recap from interim Wakefield meeting
	- 400 MHz.km minimum modal bandwidth is needed to support   
	  500 meters at 1.25 Gbaud
	- 500 MHz.km minimum modal bandwidth was recommended to   
	  support 500 meters at 1.25 Gbaud
	- Some confusion was noted over the assumptions used to   
	  determine link length
	- A strong desire to support the embedded base was also   
	  noted
	- It was unclear what link length is necessary to support   
	  the embedded base

4. Maximum link length @ 160 MHz.km
	Source rise time		Source spectral width
					5 nm	7 nm	9 nm
		.25 ns			271	267	261
		.35 ns			257	253	247
		.45 ns			236	232	227

5. Maximum link length @ 400 MHz.km
	Source rise time		Source spectral width
					5 nm	7 nm	9 nm
		.25 ns			623   	574	524
		.35 ns			590	544	496
		.45 ns			543	500	456

6. Maximum link length @ 500 MHz.km
	Source rise time		Source spectral width
					5 nm	7 nm	9 nm
		.25 ns			742	663	589
		.35 ns			702	627	557
		.45 ns			645	577	512

7. Proposed goals
	- Support lowest cost system solution
	- Independently evaluate alternatives going forward
		- Embedded base
		- New builds
	- Allow all capable source technologies by supporting   
	  both wavelength windows (850 nm and 1300 nm)
	- Support the embedded base to the extent possible

8. Optical LAN paradigms
	- Bandwidth requirements will continue to escalate
	- Multimode fiber will be lowest cost solution for LAN   
	  applications
	- Short wavelength source technology has outpaced long   
	  wavelength source technology requiring improved first   
	  window performance
	- 62.5 mm fiber is optimized for operation at 1300 nm
	- 50 mm fiber has adequate bandwidth to support both       
	  wavelength windows   
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9. The embedded base
	- How do we characterize the embedded base?
		- What is the distribution of link lengths?
		- What % will 300 meters support? (51%)
		- What % will 500 meters support? (56%)
		- What about the 1-2 km backbones?
	- The current embedded base represents less than 30% of   
	  the total NA market

10. Bandwidth (length) enhancement
	- Solutions will exist for enhancing bandwidth and   
	  therefore length
		- Controlled launches
		- Using 1300 nm single-mode transceivers
		- Receiver equalization
		- Wavelength division multiplexing
	- We should certainly consider the merits of each but   
	  understand that they may not represent the most   
	  economical nor best technical solution
	- Any enhancement most likely will apply for higher   
	  minimum bandwidth fibers thereby further extending   
	  length capability


11. Enhanced BW with controlled launch
	- TIA is studying alternative launch definitions
	- Need in excess of 3x improvement
	- The results to date are inconclusive
	  	- high variability
		- many unknowns (fiber characterization, source   
		  characterization, etc.)
		- added cost to produce a specific launch
	- More time is needed to fully characterize
	- Recommend deferring any implementation of these   
	  techniques until TIA completes their work

12. The case for 50 um multimode fiber
	- 50 um offers higher performance
		- 50 um has lower attenuation
		- 50 um has higher bandwidth
		- 50 um can support 500 meters minimum at 1.25   
		  Gbaud
		- 50 um supports both 850 nm and 1300 nm   
		  solutions   
	- 50 um fiber is a standard fiber solution
		- 50 um fiber is recognized in ISO/IEC 11801   
		  Generic Cabling
		- 50 um fiber is the preferred cable plant for   
		  short wavelength Fibre Channel solutions
		- 50 um fiber is defined in ITU-T G.651 and IEC   
		  793-2

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13. Summary
	- 50 um fiber can support 1.25 Gbaud over at least a 500   
	  meter distance
	- 62.5 mm fiber can support 1.25 Gbaud over at least a   
	  200 meter distance
	- Continue to study options to support extended link   
	  lengths for both fibers
	- More work is needed to fully understand the effects of   
	  controlled launch