[c-nsp] Good 10GE Metro switch

[Joe Loiacono]

Thanks Gert. Great information.

Turns out the fiber length is about 60km, but it is testing at 13dB for 
1550 nm. This winds up fitting in the 24dB optical budget for the 
XENPAK-10GB-ZR (80 km). I have removed  dB for connectors and potential 
splices as well.

Next challenge: On the other end of the connection is a Juniper MX. So 
here we go again ...

PS: Here's a good link for understanding how to calculate optical budgets 
if anyone needs it:

http://www.transition.com/TransitionNetworks/Learning/Whitepaper/Optical.aspx

Joe




Gert Doering <gert at greenie.muc.de> 
08/16/2008 11:29 AM

To
Joe Loiacono/CIV/CSC at CSC
cc
cisco-nsp at puck.nether.net
Subject
Re: [c-nsp] Good 10GE Metro switch






Hi,

On Mon, Aug 11, 2008 at 05:08:23PM -0400, Joe Loiacono wrote:
> PS - Should I worry (alot) about being at or slightly above the 40 Km 
> distance?

The key question is, how much loss (in dB) do you have on that line, and
on the tolerances of the X2 optics in question - a "best case" X2 will
transmit with +4.0 dBm, while a "worst case" X2 will transmit with -4.7 
dBm,
according to:

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/hardware/Module_Installation/Mod_Install_Guide/0btransc.html


- so with a receiver sensitivity of -15.8 dBm, you have a power budget of
11.1 dB to 19.8 dB.   11.1 dB is very tight for a 40km span - you need 
good
fibers, and nearly no patches in between (every patch brings about 0.5 dB 
loss).

You need to ask your carrier about the attenuation of the fiber path.

gert

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Gert Doering - Munich, Germany gert at greenie.muc.de
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