[AusNOG] Fiber connectivity

Fri Apr 20 11:34:01 EST 2012

Agree with Kevin

Also when talking about Cisco SFP's this is a good link to bookmark for
future:

http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product
_data_sheet0900aecd8033f885.html 

has some estimations of distance but these are conservative as you'd
expect - actual distance achieved depends upon fibre loss and other
linear/non-linear effects that I won't bore everyone with that are
generally worse on MMF

Now OM1 at 1300nm has a loss of 1.5dB per km so that won't be the
problem as long as the mode conditioning cables are used but as we're
all saying the loss of the 'hops' is the main loss based issue (once you
have mode conditioners)

The SFP in question being a GLC-LH-SM has a tx power of as low as
-9.5dBm and a lowest acceptable receive level at -20dBm, which means we
have as little as 10.5dB to play with one reflection or splice can be as
high as .5dB if done poorly but still 0.1dB if done well so it all adds
up

Recommend getting a power meter onto the fibre and see what loss there
is at 1300nm (1310nm)

Darren

From: ausnog-bounces at lists.ausnog.net
[mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Kevin Harm
Sent: Friday, 20 April 2012 11:15 AM
To: Christopher Pollock; Qui Le
Cc: ausnog at lists.ausnog.net
Subject: Re: [AusNOG] Fiber connectivity

And be aware of the speed / distance limitations

For OM1, typical transmission speed and distance limits are 100 Mbit/s
for distances up to 2 km (100BASE-FX
<http://en.wikipedia.org/wiki/100BASE-FX> ), 1 Gbit/s to 220-550 m
(1000BASE-SX <http://en.wikipedia.org/wiki/1000BASE-SX> ), and 10 Gbit/s
to 300 m (10GBASE-SR
<http://en.wikipedia.org/wiki/10_Gigabit_Ethernet#10GBASE-SR> )

And, if each hop that you refer to is a patching point, you will
introduce loss along the way.

Kev

From: ausnog-bounces at lists.ausnog.net
[mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Christopher
Pollock
Sent: Friday, 20 April 2012 10:55 AM
To: Qui Le
Cc: ausnog at lists.ausnog.net
Subject: Re: [AusNOG] Fiber connectivity

Sounds like you're using single mode transceivers with multimode fibre
there.  Since SM optics rely on total internal reflection and multimode
is basically bendy plastic, that will probably never work.  You need
some multimode SX SFPs.

Cheers,
--
Christopher Pollock,
io Networks Pty Ltd.

e. chris at ionetworks.com.au
p. 1300 1 2 4 8 16

d. 07 3188 7588

m. 0410 747 765

f. 07 3245 0843 

skype: christopherpollock

twitter.com/chrisionetworks

http://www.ionetworks.com.au
In-house, Outsourced.

On Fri, Apr 20, 2012 at 10:44 AM, Qui Le <QLe at sydneyoperahouse.com>
wrote:

We run 550m of OM1 fibre from our Cisco core to a remote site over 6
hops included rack to rack and we can not

seem  to get any connectivity. Using both Cisco GLC-LH-SM transceivers
at both the Core & access Switch.

Does anyone know if there are hops limitations for long haul fibres.

Any advise is much appreciated.

Thanks

Qui Le

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