Re: [AFMUG] Single mode attenuators needed at 30m

[Faisal Imtiaz]

Just to clarify for the inquiring minds... 

10km & 20km optics tend to have the same TX power, but 20km have better RX 
sensitivity. 

There is a fair amount of variance by MFG in specs, and also variance in 
individual optics out of the same batch. 

So stuff that is TX with less than 1db of power, you should be perfectly fine.. 
but stuff that is TX with more then 1db of power, then you should attenuate to 
make sure you are getting about a -3 on RX. 

Faisal Imtiaz 
Snappy Internet & Telecom 
7266 SW 48 Street 
Miami, FL 33155 
Tel: 305 663 5518 x 232 

Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net 

> From: "George Skorup" <geo...@cbcast.com>
> To: af@afmug.com
> Sent: Wednesday, September 14, 2016 9:55:22 PM
> Subject: Re: [AFMUG] Single mode attenuators needed at 30m

> I use the MikroTik and FS 20km SFPs with short patch cables all the time.
> Nothing bad has happened yet. DDM reports the Rx power around -6dBm, but you
> can't always trust the DDM data, however I highly doubt they're overloaded.
> Then we have customers at about 2-4 miles usually around -9 to -11. When the
> contractor doesn't screw up anyway. Had a couple at -21 and they still worked.
> Not even any errors with traffic load.

> I agree completely, buy a light meter.

> On 9/14/2016 8:16 PM, Faisal Imtiaz wrote:

>> My humble suggestion:-

>> invest in a light meter. not need to guess..
>> Get a $50 unit from FS.com or amazon... they are not junk, and get the job 
>> done.

>> Standard optics (SMF) 10km should be fine with shorter cables.
>> LR (Long Range) 40K or up... you can have them overload the receiver...

>> A tip shared from the field
>> Keep an #2 pencil handy if you need to make an attenuation in a hurry 
>> !...
>> take the fiber cable and start warping it around the pencil as tightly as you
>> can ..
>> and tape it so that it does not unwind.

>> I have tested this  using a light meter... and yes it does work, you may
>> need to give it 15 or more turns

>> BTW those optics putting out 4db those are meant to light up 40km or 60km
>> links.. but are also used in link where there is lots of loss expected due to
>> Mux/Demux or other passive device..
>> and yes you don't want to use these with a short cables :)

>> Faisal Imtiaz
>> Snappy Internet & Telecom
>> 7266 SW 48 Street
>> Miami, FL 33155
>> Tel: 305 663 5518 x 232

>> Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net

>>> From: "trey" <t...@3dsc.co>
>>> To: af@afmug.com
>>> Sent: Wednesday, September 14, 2016 7:08:55 PM
>>> Subject: Re: [AFMUG] Single mode attenuators needed at 30m

>>> You should not need any attenuation if you are using the same lr sfp/xfp on 
>>> both
>>> ends. However there is a small chance if they are different part numbers or
>>> manufacturers that one may transmit at the same or greater than the others 
>>> max
>>> receive level. Typically it is a .5-1db tx with a max rx of 3-4. I have ran
>>> into some 4db tx XFPs though. It will probably work fine like that, but I 
>>> have
>>> had a couple trickle errors under high utilization.
>>> I would say it's always best to keep some attenuators on hand probably 5db 
>>> and
>>> 10db with those you can make just about any optic work at any distance less
>>> than what they are rated. I personally carry around everything from 1-20db
>>> because of manualy balancing dwdm systems and seem to go through 4,7 and 13s
>>> the most.

>>>  Original message 
>>> From: Chuck McCown <ch...@wbmfg.com>
>>> Date: 9/14/16 5:19 PM (GMT-06:00)
>>> To: af@afmug.com
>>> Subject: Re: [AFMUG] Single mode attenuators needed at 30m

>>> The SFP spec will have an absolute maximum RX level. If I remember 
>>> correctly,
>>> last one I checked was higher than the max TX level of 4 dBm. Seems like the
>>> absolute max RX was something like 16 or 20 dBm.
>>> From: Eric Kuhnke
>>> Sent: Wednesday, September 14, 2016 2:41 PM
>>> To: af@afmug.com
>>> Subject: Re: [AFMUG] Single mode attenuators needed at 30m
>>> Those are totally safe to use with even a 1 meter fiber patch cable between 
>>> two
>>> pieces of gear in the same rack.

>>> On Wed, Sep 14, 2016 at 1:39 PM, TJ Trout < t...@voltbb.com > wrote:

>>>> 1310 10gb 10km
>>>> On Wed, Sep 14, 2016 at 1:38 PM, Eric Kuhnke < eric.kuh...@gmail.com > 
>>>> wrote:

>>>>> What frequency and tx

Re: [AFMUG] Single mode attenuators needed at 30m

[George Skorup]

I use the MikroTik and FS 20km SFPs with short patch cables all the 
time. Nothing bad has happened yet. DDM reports the Rx power around 
-6dBm, but you can't always trust the DDM data, however I highly doubt 
they're overloaded. Then we have customers at about 2-4 miles usually 
around -9 to -11. When the contractor doesn't screw up anyway. Had a 
couple at -21 and they still worked. Not even any errors with traffic load.


I agree completely, buy a light meter.

On 9/14/2016 8:16 PM, Faisal Imtiaz wrote:

My humble suggestion:-

invest in a light meter.  not need to guess..
Get a $50 unit from FS.com or amazon... they are not junk, and get the 
job done.


Standard optics (SMF) 10km should be fine  with shorter cables.
LR (Long Range) 40K or up... you can have them overload the receiver...

A tip shared from the field
Keep an #2 pencil handy if you need to make an attenuation in a 
hurry !... take the fiber cable and start warping it around the pencil 
as tightly as you can ..

and tape it so that it does not unwind.

I have tested this  using a light meter... and yes it does work, 
you may need to give it 15 or more turns


BTW those optics putting out 4db  those are meant to light up 40km or 
60km links.. but are also used in link where there is lots of loss 
expected due to Mux/Demux or other passive device..

and yes you don't want to use these with a short cables :)

Faisal Imtiaz
Snappy Internet & Telecom
7266 SW 48 Street
Miami, FL 33155
Tel: 305 663 5518 x 232

Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net



*From: *"trey" <t...@3dsc.co>
*To: *af@afmug.com
*Sent: *Wednesday, September 14, 2016 7:08:55 PM
*Subject: *Re: [AFMUG] Single mode attenuators needed at 30m

You should not need any attenuation if you are using the same lr
sfp/xfp on both ends. However there is a small chance if they are
different part numbers or manufacturers that one may transmit at
the same or greater than the others max receive level. Typically
it is a .5-1db tx with a max rx of 3-4. I have ran into some 4db
tx XFPs though. It will probably work fine like that, but I have
had a couple trickle errors under high utilization.
I would say it's always best to keep some attenuators on hand
probably 5db and 10db with those you can make just about any optic
work at any distance less than what they are rated. I personally
carry around everything from 1-20db because of manualy balancing
dwdm systems and seem to go through 4,7 and 13s the most.

 Original message 
From: Chuck McCown <ch...@wbmfg.com>
Date: 9/14/16 5:19 PM (GMT-06:00)
To: af@afmug.com
Subject: Re: [AFMUG] Single mode attenuators needed at 30m

The SFP  spec will have an absolute maximum RX level.  If I
remember correctly, last one I checked was higher than the max TX
level of 4 dBm.  Seems like the absolute max RX was something like
16 or 20 dBm.
*From:* Eric Kuhnke <mailto:eric.kuh...@gmail.com>
*Sent:* Wednesday, September 14, 2016 2:41 PM
*To:* af@afmug.com <mailto:af@afmug.com>
    *Subject:* Re: [AFMUG] Single mode attenuators needed at 30m
Those are totally safe to use with even a 1 meter fiber patch
cable between two pieces of gear in the same rack.

On Wed, Sep 14, 2016 at 1:39 PM, TJ Trout <t...@voltbb.com
<mailto:t...@voltbb.com>> wrote:

1310 10gb 10km
On Wed, Sep 14, 2016 at 1:38 PM, Eric Kuhnke
<eric.kuh...@gmail.com <mailto:eric.kuh...@gmail.com>> wrote:

What frequency and tx power of singlemode?  You do not
need to attenuate 1GbE 1310nm LX (5-10km reach) or 10GbE
1310nm LX optics for very short distances. Tons of ISPs
use all 1310/LX optics for intra-rack and intra-suite
fiber XCs because they're cheap, easy and multimode is dumb.

If you are using optics which are marketed as capable of
20, 40 or more km reach (and/or 1490nm, 1550nm optics) you
do need to attenuate on the Rx.
On Wed, Sep 14, 2016 at 11:20 AM, TJ Trout <t...@voltbb.com
<mailto:t...@voltbb.com>> wrote:

Do I need to pad my optics at 100ft? Or could someone
tell me how to estimate the loss so I can compare to
the spec?

Re: [AFMUG] Single mode attenuators needed at 30m

[Faisal Imtiaz]

My humble suggestion:- 

invest in a light meter. not need to guess.. 
Get a $50 unit from FS.com or amazon... they are not junk, and get the job 
done. 

Standard optics (SMF) 10km should be fine with shorter cables. 
LR (Long Range) 40K or up... you can have them overload the receiver... 

A tip shared from the field 
Keep an #2 pencil handy if you need to make an attenuation in a hurry !... 
take the fiber cable and start warping it around the pencil as tightly as you 
can .. 
and tape it so that it does not unwind. 

I have tested this  using a light meter... and yes it does work, you may 
need to give it 15 or more turns 

BTW those optics putting out 4db those are meant to light up 40km or 60km 
links.. but are also used in link where there is lots of loss expected due to 
Mux/Demux or other passive device.. 
and yes you don't want to use these with a short cables :) 

Faisal Imtiaz 
Snappy Internet & Telecom 
7266 SW 48 Street 
Miami, FL 33155 
Tel: 305 663 5518 x 232 

Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net 

> From: "trey" <t...@3dsc.co>
> To: af@afmug.com
> Sent: Wednesday, September 14, 2016 7:08:55 PM
> Subject: Re: [AFMUG] Single mode attenuators needed at 30m

> You should not need any attenuation if you are using the same lr sfp/xfp on 
> both
> ends. However there is a small chance if they are different part numbers or
> manufacturers that one may transmit at the same or greater than the others max
> receive level. Typically it is a .5-1db tx with a max rx of 3-4. I have ran
> into some 4db tx XFPs though. It will probably work fine like that, but I have
> had a couple trickle errors under high utilization.
> I would say it's always best to keep some attenuators on hand probably 5db and
> 10db with those you can make just about any optic work at any distance less
> than what they are rated. I personally carry around everything from 1-20db
> because of manualy balancing dwdm systems and seem to go through 4,7 and 13s
> the most.

>  Original message 
> From: Chuck McCown <ch...@wbmfg.com>
> Date: 9/14/16 5:19 PM (GMT-06:00)
> To: af@afmug.com
> Subject: Re: [AFMUG] Single mode attenuators needed at 30m

> The SFP spec will have an absolute maximum RX level. If I remember correctly,
> last one I checked was higher than the max TX level of 4 dBm. Seems like the
> absolute max RX was something like 16 or 20 dBm.
> From: Eric Kuhnke
> Sent: Wednesday, September 14, 2016 2:41 PM
> To: af@afmug.com
> Subject: Re: [AFMUG] Single mode attenuators needed at 30m
> Those are totally safe to use with even a 1 meter fiber patch cable between 
> two
> pieces of gear in the same rack.

> On Wed, Sep 14, 2016 at 1:39 PM, TJ Trout < t...@voltbb.com > wrote:

>> 1310 10gb 10km
>> On Wed, Sep 14, 2016 at 1:38 PM, Eric Kuhnke < eric.kuh...@gmail.com > wrote:

>>> What frequency and tx power of singlemode? You do not need to attenuate 1GbE
>>> 1310nm LX (5-10km reach) or 10GbE 1310nm LX optics for very short distances.
>>> Tons of ISPs use all 1310/LX optics for intra-rack and intra-suite fiber XCs
>>> because they're cheap, easy and multimode is dumb.

>>> If you are using optics which are marketed as capable of 20, 40 or more km 
>>> reach
>>> (and/or 1490nm, 1550nm optics) you do need to attenuate on the Rx.
>>> On Wed, Sep 14, 2016 at 11:20 AM, TJ Trout < t...@voltbb.com > wrote:

>>>> Do I need to pad my optics at 100ft? Or could someone tell me how to 
>>>> estimate
>>>> the loss so I can compare to the spec?

Re: [AFMUG] Single mode attenuators needed at 30m

[trey]

You should not need any attenuation if you are using the same lr sfp/xfp on 
both ends. However there is a small chance if they are different part numbers 
or manufacturers that one may transmit at the same or greater than the others 
max receive level. Typically it is a .5-1db tx with a max rx of 3-4. I have ran 
into some 4db tx XFPs though. It will probably work fine like that, but I have 
had a couple trickle errors under high utilization.
I would say it's always best to keep some attenuators on hand probably 5db and 
10db with those you can make just about any optic work at any distance less 
than what they are rated. I personally carry around everything from 1-20db 
because of manualy balancing dwdm systems and seem to go through 4,7 and 13s 
the most.
 Original message From: Chuck McCown <ch...@wbmfg.com> Date: 
9/14/16  5:19 PM  (GMT-06:00) To: af@afmug.com Subject: Re: [AFMUG] Single mode 
attenuators needed at 30m 



The SFP  spec will have an absolute maximum RX level.  If I 
remember correctly, last one I checked was higher than the max TX level of 4 
dBm.  Seems like the absolute max RX was something like 16 or 20 dBm.


 

From: Eric Kuhnke 
Sent: Wednesday, September 14, 2016 2:41 PM
To: af@afmug.com 
Subject: Re: [AFMUG] Single mode attenuators needed at 
30m
 

Those are totally safe to use with even a 1 meter fiber patch cable 
between two pieces of gear in the same rack.



 
On Wed, Sep 14, 2016 at 1:39 PM, TJ Trout <t...@voltbb.com> wrote:


  1310 10gb 10km
  
   
  On Wed, Sep 14, 2016 at 1:38 PM, Eric Kuhnke 
  <eric.kuh...@gmail.com> wrote:

  
What frequency and tx power of singlemode?  You do not 
need to attenuate 1GbE 1310nm LX (5-10km reach) or 10GbE 1310nm LX optics 
for very short distances. Tons of ISPs use all 1310/LX optics for 
intra-rack 
and intra-suite fiber XCs because they're cheap, easy and multimode is 
dumb. 


If you are using optics which are marketed as capable of 20, 40 or 
more km reach (and/or 1490nm, 1550nm optics) you do need to attenuate on 
the 
Rx.




 
On Wed, Sep 14, 2016 at 11:20 AM, TJ Trout 
<t...@voltbb.com> wrote:


  Do I need to pad my optics at 100ft? Or could someone tell me 
  how to estimate the loss so I can compare to the 
spec?
 
   
 

Re: [AFMUG] Single mode attenuators needed at 30m

[Chuck McCown]

The SFP  spec will have an absolute maximum RX level.  If I remember correctly, 
last one I checked was higher than the max TX level of 4 dBm.  Seems like the 
absolute max RX was something like 16 or 20 dBm.

From: Eric Kuhnke 
Sent: Wednesday, September 14, 2016 2:41 PM
To: af@afmug.com 
Subject: Re: [AFMUG] Single mode attenuators needed at 30m

Those are totally safe to use with even a 1 meter fiber patch cable between two 
pieces of gear in the same rack.



On Wed, Sep 14, 2016 at 1:39 PM, TJ Trout <t...@voltbb.com> wrote:

  1310 10gb 10km

  On Wed, Sep 14, 2016 at 1:38 PM, Eric Kuhnke <eric.kuh...@gmail.com> wrote:

What frequency and tx power of singlemode?  You do not need to attenuate 
1GbE 1310nm LX (5-10km reach) or 10GbE 1310nm LX optics for very short 
distances. Tons of ISPs use all 1310/LX optics for intra-rack and intra-suite 
fiber XCs because they're cheap, easy and multimode is dumb. 

If you are using optics which are marketed as capable of 20, 40 or more km 
reach (and/or 1490nm, 1550nm optics) you do need to attenuate on the Rx.


On Wed, Sep 14, 2016 at 11:20 AM, TJ Trout <t...@voltbb.com> wrote:

  Do I need to pad my optics at 100ft? Or could someone tell me how to 
estimate the loss so I can compare to the spec?

Re: [AFMUG] Single mode attenuators needed at 30m

[Eric Kuhnke]

Those are totally safe to use with even a 1 meter fiber patch cable between
two pieces of gear in the same rack.


On Wed, Sep 14, 2016 at 1:39 PM, TJ Trout  wrote:

> 1310 10gb 10km
>
> On Wed, Sep 14, 2016 at 1:38 PM, Eric Kuhnke 
> wrote:
>
>> What frequency and tx power of singlemode?  You do not need to attenuate
>> 1GbE 1310nm LX (5-10km reach) or 10GbE 1310nm LX optics for very short
>> distances. Tons of ISPs use all 1310/LX optics for intra-rack and
>> intra-suite fiber XCs because they're cheap, easy and multimode is dumb.
>>
>> If you are using optics which are marketed as capable of 20, 40 or more
>> km reach (and/or 1490nm, 1550nm optics) you do need to attenuate on the Rx.
>>
>> On Wed, Sep 14, 2016 at 11:20 AM, TJ Trout  wrote:
>>
>>> Do I need to pad my optics at 100ft? Or could someone tell me how to
>>> estimate the loss so I can compare to the spec?
>>>
>>
>>
>

Re: [AFMUG] Single mode attenuators needed at 30m

[TJ Trout]

1310 10gb 10km

On Wed, Sep 14, 2016 at 1:38 PM, Eric Kuhnke  wrote:

> What frequency and tx power of singlemode?  You do not need to attenuate
> 1GbE 1310nm LX (5-10km reach) or 10GbE 1310nm LX optics for very short
> distances. Tons of ISPs use all 1310/LX optics for intra-rack and
> intra-suite fiber XCs because they're cheap, easy and multimode is dumb.
>
> If you are using optics which are marketed as capable of 20, 40 or more km
> reach (and/or 1490nm, 1550nm optics) you do need to attenuate on the Rx.
>
> On Wed, Sep 14, 2016 at 11:20 AM, TJ Trout  wrote:
>
>> Do I need to pad my optics at 100ft? Or could someone tell me how to
>> estimate the loss so I can compare to the spec?
>>
>
>

Re: [AFMUG] Single mode attenuators needed at 30m

[Eric Kuhnke]

What frequency and tx power of singlemode?  You do not need to attenuate
1GbE 1310nm LX (5-10km reach) or 10GbE 1310nm LX optics for very short
distances. Tons of ISPs use all 1310/LX optics for intra-rack and
intra-suite fiber XCs because they're cheap, easy and multimode is dumb.

If you are using optics which are marketed as capable of 20, 40 or more km
reach (and/or 1490nm, 1550nm optics) you do need to attenuate on the Rx.

On Wed, Sep 14, 2016 at 11:20 AM, TJ Trout  wrote:

> Do I need to pad my optics at 100ft? Or could someone tell me how to
> estimate the loss so I can compare to the spec?
>

Re: [AFMUG] Single mode attenuators needed at 30m

[Sterling Jacobson]

Not sure what you are asking.

Do your SFP modules not scale back on their transmit?

I’ve got 20km SFP modules I can plug in with a 3’ cord and work just fine, they 
regulate their power output.

From: Af [mailto:af-boun...@afmug.com] On Behalf Of TJ Trout
Sent: Wednesday, September 14, 2016 12:21 PM
To: af@afmug.com
Subject: [AFMUG] Single mode attenuators needed at 30m


Do I need to pad my optics at 100ft? Or could someone tell me how to estimate 
the loss so I can compare to the spec?

Re: [AFMUG] Single mode attenuators needed at 30m

[Justin Wilson]

There is a good chance you may need to.  I have seen 200 foot runs go for 
years, then all of a sudden become “too hot”.  This was noticed when traffic 
levels increased and things became more busy.   Does it have to be single mode? 
I know companies are standardizing more and more on single mode.  But multimode 
still has it’s place.  You can actually get 10 gig multimode.  the cost may be 
higher than just adding in attenuators though.


Justin Wilson
j...@mtin.net

---
http://www.mtin.net Owner/CEO
xISP Solutions- Consulting – Data Centers - Bandwidth

http://www.midwest-ix.com  COO/Chairman
Internet Exchange - Peering - Distributed Fabric

> On Sep 14, 2016, at 2:20 PM, TJ Trout  wrote:
> 
> Do I need to pad my optics at 100ft? Or could someone tell me how to estimate 
> the loss so I can compare to the spec?
>