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Re: 1310 nm vs. 1550 nm links greater than 40 km


We have an objective as a task force to support a distance of at least 40 
km over SM fiber.

On the basis of discussions with multiple customers especially service 
providers over the last year, I have determined that the market requirement 
exists to support distances of 50 to 70 km on SM fiber.

Therefore, I support the PMD that can go much further than 40 km and attach 
to existing infrastructure: 1550 nm serial.


Bruce Tolley
Enterprise Line of Business
Cisco Systems

At 12:11 PM 5/31/00 -0700, Vipul Bhatt wrote:

>I would like to respond to a couple of comments made on this
>reflector about the possibility of using 1310 nm wavelength for 40
>km Serial links. I think we should stay with 1550 nm.
>Following a presentation I gave at the 10GEA Santa Clara meeting,
>and also during Serial SIG discussions, the feedback I have received
>from many members is that for Metro Area Networks, it is desirable
>to be able to extend the link distance beyond the stated 40 km goal.
>Metro Area links capable of supporting distances beyond 40 kms will
>be a significant potential application of 10G Ethernet. This does
>not mean that we need to include optical amplifiers or dispersion
>compensation blocks in the standard, only that our link should be
>compatible with them. Compatibility with long distance
>infrastructure tilts the balance in favor of 1550 nm. Limiting the
>operation of this link to 40 kms will be like clipping the wings of
>10G Ethernet.
>If you ask the question - "Do we want a link that is the lowest cost
>solution for 40 kms, or do we want a link that is more expensive but
>capable of plugging into the long distance infrastructure?" - my
>recommendation is to choose the latter.