Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

RE: Supporting Installed Fibre

Bruce (et al):

There are many reasons why we ended up with the distance objectives we did.
I am especially grateful that we have what we do. 

While it is of great interest to maximumize the distance we can acheive,
this cannot be done independent of cost, reliability, risk,
manufacturability, IP, and numerous other issues. I do not believe that we
have sufficient information at this point in time to make these trade-offs.
I do believe that it is important for us to understand the matrix and make
informed decisions. I believe that the best PMD solution for distance is
different from the best PMD solution for cost is different from the best PMD
solution for reliability....

Your point is well taken and should not be forgotten. In fact, we all hope
that your fiber survey ad-hoc will come up with some really good data that
will help to make our future decisions and trade-offs easier. In the mean
time, let's construct the criteria list and get to work information
gathering and prioritizing.


> -----Original Message-----
> From: Bruce_Tolley@xxxxxxxx [mailto:Bruce_Tolley@xxxxxxxx]
> Sent: Monday, September 20, 1999 1:07 PM
> To: Alan Flatman
> Cc: IEEE 802.3 HSSG
> Subject: Re: Supporting Installed Fibre
> Alan:
> Thanks for re-stating the statistics.  We have a goal of 
> supporting 100 meters
> on the installed MM fiber. We have a goal of supporting 300 
> meters on MM fiber.
> I am not sure I want to start a debate on moving goal posts 
> but I want everyone
> to be crystal clear on the fact that these two goals as 
> stated miss the
> installed base of MM building backbones.
> Although during the debate on distances, it was stated that 
> we could change or
> add goals later, apart from HP, I have seen little indication from the
> optoelectronics companies that they are interested in 
> supporting distances in
> the ranges of 200 meters on installed MM fiber.
> Customers are currently  using 1000BASE-SX at the specified 
> distance of 220
> meters. They will expect to run 10 GbE on the same links.  
> Not many of them will
> want to pull a new "enhanced" MM fiber.
> Bruce Tolley
> Manager, Business Development, 3Com
> Alan Flatman <a_flatman@xxxxxxxxxxxxxx> on 09/16/99 07:29:35 AM
> Sent by:  Alan Flatman <a_flatman@xxxxxxxxxxxxxx>
> To:   "IEEE 802.3 HSSG" <stds-802-3-hssg@xxxxxxxx>
> cc:    (Bruce Tolley/HQ/3Com)
> Subject:  Supporting Installed Fibre
> I would like to offer some perspectives on supporting 
> installed multimode
> fibre links.
> Firstly, let's remind ourselves of the statistics. I 
> presented a survey of
> installed fibre links in Montreal and compared this with 
> existing data:
> I found 25% of installed building backbone links within 100m
> The maximum percentage found by other surveys for this 
> distance was 35%
> I would add approximately 3% to this figure to include in-range campus
> links
> I found 58% of installed building backbone links within 200m
> The maximum percentage found by other surveys for this 
> distance was 70%
> I would add approximately 4% to this figure to include in-range campus
> links
> I found 88% of installed building backbone links within 300m
> Other surveys found slightly less, so there was good 
> correlation for 300m
> I would add approximately 5% to this figure to include in-range campus
> links
> It's worth noting that cabling standards and installers treat 
> horizontal
> (generally copper) and backbone (generally fibre) cabling 
> differently. The
> horizontal medium is chosen and installed for generic use and 
> for long life
> (typically 10 years). The backbone medium is more 
> application-dependent.
> Standards for structured cabling have tried to specify 
> optical fibre for
> generic application but we do not believe that this is possible.
> Consequently, we expect installed fibre backbone links to 
> turnover more
> frequently. As a consultant, I have been recommending a 
> combination of MMF
> and SMF in the backbone for some time.
> Having said this, some organisations will not or cannot tolerate the
> disruption associated with installing new fibre for 10GE. It 
> will therefore
> be useful to offer them a solution. Refer to the above 
> statistics in making
> this decision.
> I tend to agree with Bruce Tolley that a 200m target for 
> installed MMF is
> much  better than 100m. I also got the impression from the 
> Montreal meeting
> that 300m was possible but complex and expensive. I would 
> like to hear more
> from the optoelectronics industry before we move the goalposts.
> Regards,
> Alan Flatman