IEEE is seeking feedback from network operators etc on the reach
requirements for 40GE & 100GE.
If you have direct feedback to give, please contact Chris Cole directly
(email address below).
This is very important as it will directly impact how much you pay for those
soon to be cherished 40 & 100 GE hardware in the future. I believe
information on how many patch panel connections you expect the links to go
through is also highly valued.
Regards
Bora
------ Forwarded Message
A practical question here: does anyone know offhand if 4km reach is
adequate for interbuilding access (i.e., DC[124] to DC3) access at
Equinix Ashburn, including worst-case interior wiring and cross
connects? I'm thinking that's cutting it close. The enterprise
people are substantially less likely to find themselves with a lot of
interconnections in a GCE (Ginormous Campus Environment) than we are,
and I suspect that skews the 90% number a bit. Folks who are more
familiar with the layout of other facilities may wish to chime in here.
---Rob
Bora Akyol <bora.akyol@aprius.com> writes:
Another nice feature would be cheap cheap optics with say 500M-1KM reach for inter-floor connects.
A practical question here: does anyone know offhand if 4km reach is
adequate for interbuilding access (i.e., DC[124] to DC3) access at
Equinix Ashburn, including worst-case interior wiring and cross
connects? I'm thinking that's cutting it close. The enterprise
people are substantially less likely to find themselves with a lot of
interconnections in a GCE (Ginormous Campus Environment) than we are,
and I suspect that skews the 90% number a bit. Folks who are more
familiar with the layout of other facilities may wish to chime in here.
I'm not in any of the Equinix facilities, but I do run a decent-sized urban campus network and a 3km-4km distance limitation would be cutting it really close for me in some cases. Some of the 10G links on my backbone today do require multiple physical cross-connects, which would eats into the link budget. Most of my backbone connections work find with 10G-LX4 optics, but there are a few places where 10G-ER is needed.
I haven't read the draft spec yet to see what's being proposed for a link budget at 3/4/10km, but that's just as important as the physical distance.
jms
"Justin M. Streiner" <streiner@cluebyfour.org> writes:
I haven't read the draft spec yet to see what's being proposed for a
link budget at 3/4/10km, but that's just as important as the physical
distance.
That's a really good point, and one which I didn't originally consider
pre-coffee. 
Link budget information on page 4, here:
Relative cost estimates on page 5.
Suppositions for ingredients to link budget are here:
(page 3)
I'm kind of looking longingly at that extra 3dB, given the slight
marginal extra cost and my knowledge of the trained chimp quality
mechanical splices that are rife in certain <cough> data centers.
---Rob
(totally disregarding the HSSG policy of talking cost and not price here)
If the cost estimate has any bearing on actual end-user purchase price, then I would say that the 3-4km reach alternative makes sense. Having a 10km reach alternative costing 60% of 40km reach optics just doesn't make sense. Today we live in a world where 10km reach optics is ~1/4 the price of 40-80km optics, what's being said in that table is that the 40km reach optics cost 2.1x of the 3km one. The 40km optics would cost 1.6x the 10km one.
Since cost of keeping spares and considering the operational expense of bringing up links with beforementioned bad connectors etc, it might even be rational to just go with 40km optics at this cost difference level.
Different optics variants need to have a distinct price difference, otherwise they're just complicating things. Otoh if we need attenuators for 40km optics on 5km links then that's a complicating factor as well. That's not been needed before.
I have three practical uses for 40G at present...
First and most obvious is router to router. In this case, if the
routers are in the same cage, there's little reason to want to be able
to push more than 100 feet. (The same applies to aggregation switches
and similar.)
The second use is links around a campus. Now we're pushing
distances. ESPECIALLY when you consider budgets due to patch losses
and so on. In this case, 3-4km is probably still adequate for me in
most cases. (Equinix's DC area will probably work with 3km as long as
they don't take it through 8 patch panels before they get to you. DC3
is the only one to be concerned about because of the added
inter-building distance.)
The third use for this is across a metro area. (Lets face it, it's
hard to find a good amount of space in any one location.) In this
case, in most areas, I have a need to use DWDM. I would still need to
do this on dark fiber since some locations can quite easily push more
than 40 gigs back to the core. So I either double my fiber costs and
buy two pair to each location or I use DWDM. So now the concern is
when my DWDM vendor will be able to mux these together. That, above
and beyond "how far can you push this?" If I've got a long run and no
place to put an amplifier in the middle, even 10km may mean I'm SOL.
So from my POV, I have a vested insterest in all three options and the
relevant orders of magnitude between each one. For the sake of
instroducing the technology, should it not persue the same path that
10GE did? That is, focus on the first condition with an eye to the
second and add the third once you've got the problems with the first
two worked out?
The 100G 40km reach (the 40G in your email I am assuming is a type) will
be a black/white code, and it will not support DWDM.
Chris