[177990] in North American Network Operators' Group
Re: MultiMode Fiber Connectivity... (850nm) Power Question
daemon@ATHENA.MIT.EDU (Justin M. Streiner)
Wed Feb 11 16:40:32 2015
X-Original-To: nanog@nanog.org
Date: Wed, 11 Feb 2015 12:41:23 -0500 (EST)
From: "Justin M. Streiner" <streiner@cluebyfour.org>
To: NANOG <nanog@nanog.org>
In-Reply-To: <582468259.1095514.1423687699056.JavaMail.zimbra@snappytelecom.net>
Errors-To: nanog-bounces@nanog.org
On Wed, 11 Feb 2015, Faisal Imtiaz wrote:
> I was looking for feedback on the following question:-
>
> When connecting two MM SFP/SFP+/XFP 's together...(short range).
>
> What should be the best practice receive power range ?
SX (1G) / SR (10G) / SR10 (100G) gear generally has a receive threshold
that's higher than the maximum launch power. They are designed for
short-reach applications (in-building, data center, etc), so no
attenuation is needed.
> Is it true that if the rx power is higher than (x?) then it shortens
> the life of the optics ?
> (assumption being made here is that MAX Rx Power is not being exceed as
> per the spec sheets of the optics)
On short-reach optics, this should never be a problem. On long-reach
optics, receiver saturation will generally result in link errors/flaps,
and possibly high rx power warnings (depending on the gear on the
receiving end), however, these can be addressed using in-line attenuators.
On very long-reach optics, such as ZX (1G) and ER/ZR (10G), it is possible
to damage the receivers with too hot of a signal because they are designed
for long spans and a certain amount of distance-based attenuation is
factored into the optical power budget.
jms
