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peter at rathlev

May 16, 2012, 2:18 AM

Post #1 of 12 (2605 views)
Permalink
Long range 10G ethernet?

(On 6500/Sup720 and with LAN cards)

We're currently using a gigabit link with a total loss of 24.1dB (at
1510 nm) from end to end. We're using some third party "120 Km"
transceivers, and this is working well.

Now we're thinking about making it a 10G link instead. Finding 10G
transceivers capable of supporting at least ~24-25dB seems tricky
though. Googling a bit reveals something like the Optospan
SPP-81D-K080T31, rated for 25dB at 1310nm. Of course we're primarily
using X2 transceivers, and that one is an SFP+.

Questions:

1) Any general ideas about how to best run 10G on 25+dB stretch without
external amplification? We'd like to avoid the extra complexity that
would introduce.

2) We might cut ~1dB by splicing in a few places instead of patching,
but we probably can't get below 23dB loss. Would using 25dB capable
transceivers on a 23dB stretch be too bold for comfort?

3) Does the OneX converter support any SFP+? Or is it somehow locked to
only support certain modules? Cisco[1] mentions only CU, SR and LR as
supported. Any (electrical) reasons OneX couldn't support any kind of
SFP+? Should we count on being able to use e.g. the aforementioned
SPP-81D-K080T31 in a OneX in e.g. a 6708 or Sup2T port?

[1]: http://www.cisco.com/en/US/prod/collateral/modules/ps5455/data_sheet_c78-547521.html

--
Peter


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p.mayers at imperial

May 16, 2012, 3:46 AM

Post #2 of 12 (2533 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

On 16/05/12 10:18, Peter Rathlev wrote:
> (On 6500/Sup720 and with LAN cards)
>
> We're currently using a gigabit link with a total loss of 24.1dB (at
> 1510 nm) from end to end. We're using some third party "120 Km"
> transceivers, and this is working well.

Out of curiosity, is this an immensely long leg, or is it just really
crappy? We had a link that was relatively short but had very high loss
(though nowhere near this bad) and the fibre provider was able to
improve this significantly more than we expected.

>
> Now we're thinking about making it a 10G link instead. Finding 10G
> transceivers capable of supporting at least ~24-25dB seems tricky
> though. Googling a bit reveals something like the Optospan
> SPP-81D-K080T31, rated for 25dB at 1310nm. Of course we're primarily
> using X2 transceivers, and that one is an SFP+.

Usually I would expect loss at 1310 to be higher than 1550, so unless
the fibre is really odd, I'd aim for a 1550 optic on this link.

>
> Questions:
>
> 1) Any general ideas about how to best run 10G on 25+dB stretch without
> external amplification? We'd like to avoid the extra complexity that
> would introduce.

One possibility might be to use a transponder with G.709 capability, and
appropriate optics. However, I'm not completely sure this will work - if
your RX light level is too low, the transceiver may refuse to link-up,
even though the extra 6dB signal/noise from the G.709 would bring it
into spec.

*If* it works, plain ER optics should run that link in combination with
G.709.

You didn't say what specific complexity puts you off amps, but if it's
just "more kit" then this solution isn't really any better, and I doubt
much cheaper, than a pair of 9dB amps.

There are also optics with embedded g.709 codecs, although I think
they're all XFP (at the moment). This is of course simpler, but you
can't run XFP in that platform (sigh)

> 2) We might cut ~1dB by splicing in a few places instead of patching,
> but we probably can't get below 23dB loss. Would using 25dB capable
> transceivers on a 23dB stretch be too bold for comfort?

Well... it's tight. I aim for a minimum of 3dB headroom, and that tends
to make me uncomfortable.

> 3) Does the OneX converter support any SFP+? Or is it somehow locked to

We've got DWDM ER (40km) SFP+ in the OneX converter, and they work fine
(both 6500/sup720 w/ 6716, and Nexus 7009 with M1 8-port).

> only support certain modules? Cisco[1] mentions only CU, SR and LR as
> supported. Any (electrical) reasons OneX couldn't support any kind of
> SFP+? Should we count on being able to use e.g. the aforementioned
> SPP-81D-K080T31 in a OneX in e.g. a 6708 or Sup2T port?

I don't see any reason this wouldn't work, absent some Cisco nonsense.
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nick at foobar

May 16, 2012, 4:18 AM

Post #3 of 12 (2542 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

On 16/05/2012 10:18, Peter Rathlev wrote:
> Now we're thinking about making it a 10G link instead. Finding 10G
> transceivers capable of supporting at least ~24-25dB seems tricky
> though.

have been there and done this. I would recommend getting external
transponders for this, and if you are, to look into getting coloured
transceivers instead of grey 120km units (not even sure if they make grey
120km transceivers), because

- getting long range wdm X2 transceivers is likely to be very expensive
because only vendor C uses X2, and everyone else in the world uses XFP or SFP+.

- if you ever move to another platform, you can be pretty much guaranteed
it won't support x2, which means that your expenditure on x2 transceivers
will become worthless

> 2) We might cut ~1dB by splicing in a few places instead of patching,
> but we probably can't get below 23dB loss. Would using 25dB capable
> transceivers on a 23dB stretch be too bold for comfort?

yes. This sounds like the sort of link where you'll have to add in a
couple of dB overhead to compensate for chromatic dispersion @10G.

Nick
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streiner at cluebyfour

May 16, 2012, 7:54 AM

Post #4 of 12 (2530 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

On Wed, 16 May 2012, Peter Rathlev wrote:

> (On 6500/Sup720 and with LAN cards)
>
> We're currently using a gigabit link with a total loss of 24.1dB (at
> 1510 nm) from end to end. We're using some third party "120 Km"
> transceivers, and this is working well.

I ended up doing something similar about two years ago on a pair of ~110Km
dark fiber links at 1G, but using external line drivers from Transition
Networks. While I would have preferred to use native Cisco optics to
drive the link, there wasn't anything available that I could plug into
a 6509 that would drive a link that far. To Transition's credit, the
links have been absolutely solid in the nearly two years they've been in
production.

> Now we're thinking about making it a 10G link instead. Finding 10G
> transceivers capable of supporting at least ~24-25dB seems tricky
> though. Googling a bit reveals something like the Optospan
> SPP-81D-K080T31, rated for 25dB at 1310nm. Of course we're primarily
> using X2 transceivers, and that one is an SFP+.

What is the distance of the fiber span? It's somewhat surprising that the
published link budget on the equivalent 1550nm module is lower - by 2 dB,
which is substantial - than the 1330nm module.

> 1) Any general ideas about how to best run 10G on 25+dB stretch without
> external amplification? We'd like to avoid the extra complexity that
> would introduce.

25+ dB is really pushing the envelope of what you can get out of something
you can plug into a switch, without amplification/regen.

> 2) We might cut ~1dB by splicing in a few places instead of patching,
> but we probably can't get below 23dB loss. Would using 25dB capable
> transceivers on a 23dB stretch be too bold for comfort?

Does your link budget include the insertion loss from the jumpers that
will connect to your equipment at each end? It might seem like splitting
hairs, but on a link with that much loss, 2 dB can make a lot of
difference, especially if the insertion loss cuts your headroom down to 1
dB, or even less.

> 3) Does the OneX converter support any SFP+? Or is it somehow locked to
> only support certain modules? Cisco[1] mentions only CU, SR and LR as
> supported. Any (electrical) reasons OneX couldn't support any kind of
> SFP+? Should we count on being able to use e.g. the aforementioned
> SPP-81D-K080T31 in a OneX in e.g. a 6708 or Sup2T port?

Not sure about this one. Haven't messed around too much with the OneX.

jms
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lists at hojmark

May 16, 2012, 12:42 PM

Post #5 of 12 (2524 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

Peter,

A Cisco-branded 10Gbase-ZR X2 actually has a power budget of (at least) 24
dBm @ 1550 nm[1]. Get the fiber cleaned, re-spliced as you suggest, and
(re-)tested (to also check for dispersion). It's likely to work just fine.

I have a couple of customers running 'grey' links at significantly more than
24 dB, and while that's not something I'd normally suggest or consider best
practice, there really is a pretty good chance that it'll work just fine.

[1]
http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6574/product_dat
a_sheet0900aecd801f92aa.html

-A
PS: Be careful if testing them in a lab. You *will* toast them if not using
attenuators.

-----Original Message-----
From: cisco-nsp-bounces [at] puck
[mailto:cisco-nsp-bounces [at] puck] On Behalf Of Peter Rathlev
Sent: 16. maj 2012 11:19
To: cisco-nsp
Subject: [c-nsp] Long range 10G ethernet?

(On 6500/Sup720 and with LAN cards)

We're currently using a gigabit link with a total loss of 24.1dB (at 1510
nm) from end to end. We're using some third party "120 Km" transceivers, and
this is working well.

Now we're thinking about making it a 10G link instead. Finding 10G
transceivers capable of supporting at least ~24-25dB seems tricky though.
Googling a bit reveals something like the Optospan SPP-81D-K080T31, rated
for 25dB at 1310nm. Of course we're primarily using X2 transceivers, and
that one is an SFP+.

[snip]

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Vinny_Abello at Dell

May 16, 2012, 2:02 PM

Post #6 of 12 (2548 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

Transition Networks makes some good stuff. I've used several of their products and they always perform as expected. One of the ones I'm using is the TN-GLC-ZX-SM-15. It's only 1Gb, but has a link budget of 37db and I've never had a problem. I think I'm currently running around the -29 to -30db range on a span that's at least 115km. They do make the TN-XFP-LR10 (which is an XFP obviously based on the model, not X2) which has a link budget of 25db @ 1550nm. That might work just fine for you, although the RX sensitivity is -24db. The TN-XFP-LR10 is also Cisco compatible.

I think that's the best you'll get from their lineup from a native transceiver you can plug into your gear, assuming you can use XFP. I might have missed another option, but they're all here:

http://www.transition.com/sfp.pdf

Hope this helps!

-Vinny

-----Original Message-----
From: cisco-nsp-bounces [at] puck [mailto:cisco-nsp-bounces [at] puck] On Behalf Of Justin M. Streiner
Sent: Wednesday, May 16, 2012 10:54 AM
To: Peter Rathlev
Cc: cisco-nsp
Subject: Re: [c-nsp] Long range 10G ethernet?

On Wed, 16 May 2012, Peter Rathlev wrote:

> (On 6500/Sup720 and with LAN cards)
>
> We're currently using a gigabit link with a total loss of 24.1dB (at
> 1510 nm) from end to end. We're using some third party "120 Km"
> transceivers, and this is working well.

I ended up doing something similar about two years ago on a pair of ~110Km
dark fiber links at 1G, but using external line drivers from Transition
Networks. While I would have preferred to use native Cisco optics to
drive the link, there wasn't anything available that I could plug into
a 6509 that would drive a link that far. To Transition's credit, the
links have been absolutely solid in the nearly two years they've been in
production.

> Now we're thinking about making it a 10G link instead. Finding 10G
> transceivers capable of supporting at least ~24-25dB seems tricky
> though. Googling a bit reveals something like the Optospan
> SPP-81D-K080T31, rated for 25dB at 1310nm. Of course we're primarily
> using X2 transceivers, and that one is an SFP+.

What is the distance of the fiber span? It's somewhat surprising that the
published link budget on the equivalent 1550nm module is lower - by 2 dB,
which is substantial - than the 1330nm module.

> 1) Any general ideas about how to best run 10G on 25+dB stretch without
> external amplification? We'd like to avoid the extra complexity that
> would introduce.

25+ dB is really pushing the envelope of what you can get out of something
you can plug into a switch, without amplification/regen.

> 2) We might cut ~1dB by splicing in a few places instead of patching,
> but we probably can't get below 23dB loss. Would using 25dB capable
> transceivers on a 23dB stretch be too bold for comfort?

Does your link budget include the insertion loss from the jumpers that
will connect to your equipment at each end? It might seem like splitting
hairs, but on a link with that much loss, 2 dB can make a lot of
difference, especially if the insertion loss cuts your headroom down to 1
dB, or even less.

> 3) Does the OneX converter support any SFP+? Or is it somehow locked to
> only support certain modules? Cisco[1] mentions only CU, SR and LR as
> supported. Any (electrical) reasons OneX couldn't support any kind of
> SFP+? Should we count on being able to use e.g. the aforementioned
> SPP-81D-K080T31 in a OneX in e.g. a 6708 or Sup2T port?

Not sure about this one. Haven't messed around too much with the OneX.

jms
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mack.mcbride at viawest

May 16, 2012, 5:41 PM

Post #7 of 12 (2536 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

Standard cisco ZR optics (X2-10GB-ZR) should meet your needs if you can reduce the loss budget by .1 db (I am assuming the loss includes jumpers).
The average on ZR is about 26 db budget. The minimum budget is 24 db.
The ZR optics generally work beyond the listed budget if you are ok operating 'out of spec'.

The OneX probably has a power limitation that prohibits using ER or ZR optics.
However it could just be software.

LR Mack McBride
Network Architect



-----Original Message-----
From: cisco-nsp-bounces [at] puck [mailto:cisco-nsp-bounces [at] puck] On Behalf Of Peter Rathlev
Sent: Wednesday, May 16, 2012 3:19 AM
To: cisco-nsp
Subject: [c-nsp] Long range 10G ethernet?

(On 6500/Sup720 and with LAN cards)

We're currently using a gigabit link with a total loss of 24.1dB (at
1510 nm) from end to end. We're using some third party "120 Km"
transceivers, and this is working well.

Now we're thinking about making it a 10G link instead. Finding 10G transceivers capable of supporting at least ~24-25dB seems tricky though. Googling a bit reveals something like the Optospan SPP-81D-K080T31, rated for 25dB at 1310nm. Of course we're primarily using X2 transceivers, and that one is an SFP+.

Questions:

1) Any general ideas about how to best run 10G on 25+dB stretch without external amplification? We'd like to avoid the extra complexity that would introduce.

2) We might cut ~1dB by splicing in a few places instead of patching, but we probably can't get below 23dB loss. Would using 25dB capable transceivers on a 23dB stretch be too bold for comfort?

3) Does the OneX converter support any SFP+? Or is it somehow locked to only support certain modules? Cisco[1] mentions only CU, SR and LR as supported. Any (electrical) reasons OneX couldn't support any kind of
SFP+? Should we count on being able to use e.g. the aforementioned
SPP-81D-K080T31 in a OneX in e.g. a 6708 or Sup2T port?

[1]: http://www.cisco.com/en/US/prod/collateral/modules/ps5455/data_sheet_c78-547521.html

--
Peter


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p.mayers at imperial

May 17, 2012, 12:11 AM

Post #8 of 12 (2500 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

On 05/17/2012 01:41 AM, Mack McBride wrote:

> The OneX probably has a power limitation that prohibits using ER or ZR optics.

That is most definitely NOT the case for ER SFP+ optics; they work just
fine in OneX converters.
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peter at rathlev

May 17, 2012, 3:14 AM

Post #9 of 12 (2493 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

On Wed, 2012-05-16 at 11:46 +0100, Phil Mayers wrote:
> Out of curiosity, is this an immensely long leg, or is it just really
> crappy?

A bit of both. :-) I think it's just short of 100 Km in total, but with
several patch cords/ODFs along the way. Some of these can be removed but
removing all would probably make too expensive compared to what we win
by running 10G.

> One possibility might be to use a transponder with G.709 capability, and
> appropriate optics.
...
> You didn't say what specific complexity puts you off amps, but if it's
> just "more kit" then this solution isn't really any better, and I doubt
> much cheaper, than a pair of 9dB amps.

Hadn't thought of the G.709 angle. But since it still requires external
equipment (for a 6500) the amplification path is probably easier.

--
Peter


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peter at rathlev

May 17, 2012, 3:53 AM

Post #10 of 12 (2502 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

On Wed, 2012-05-16 at 10:54 -0400, Justin M. Streiner wrote:
> What is the distance of the fiber span?

Just short of 100 Km. I don't have the exact number with me, but it's
something like that.

> Does your link budget include the insertion loss from the jumpers that
> will connect to your equipment at each end? It might seem like splitting
> hairs, but on a link with that much loss, 2 dB can make a lot of
> difference, especially if the insertion loss cuts your headroom down to 1
> dB, or even less.

The ~24dB was what DOM said. I just looked again and saw that it's
actually 24.3dB in one direction and 23.7dB in the other direction:

A Tx: 2.6 dBm Rx: -21.8 dBm
B Tx: 2.5 dBm Rx: -21.1 dBm

We moved the link since the last time I looked, so it's not neccesarily
the fiber having degraded in the meantime. We have the OTDR results
somewhere, and they said something like this too.

--
Peter


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peter at rathlev

May 17, 2012, 4:00 AM

Post #11 of 12 (2492 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

On Wed, 2012-05-16 at 21:42 +0200, Asbjorn Hojmark - Lists wrote:
> A Cisco-branded 10Gbase-ZR X2 actually has a power budget of (at
> least) 24 dBm @ 1550 nm[1]. Get the fiber cleaned, re-spliced as you
> suggest, and (re-)tested (to also check for dispersion). It's likely
> to work just fine.

We could try this and then keep the link out of IGP and see if it is
stable over time. It seems worth a shot at least. :-)

--
Peter


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frnkblk at iname

Jun 12, 2012, 9:07 PM

Post #12 of 12 (2334 views)
Permalink
Re: Long range 10G ethernet? [In reply to]

You generally will save some light if you skip the intermediate patch cords
and splice it through.

Frank

-----Original Message-----
From: cisco-nsp-bounces [at] puck
[mailto:cisco-nsp-bounces [at] puck] On Behalf Of Peter Rathlev
Sent: Thursday, May 17, 2012 5:14 AM
To: Phil Mayers
Cc: cisco-nsp [at] puck
Subject: Re: [c-nsp] Long range 10G ethernet?

On Wed, 2012-05-16 at 11:46 +0100, Phil Mayers wrote:
> Out of curiosity, is this an immensely long leg, or is it just really
> crappy?

A bit of both. :-) I think it's just short of 100 Km in total, but with
several patch cords/ODFs along the way. Some of these can be removed but
removing all would probably make too expensive compared to what we win
by running 10G.

> One possibility might be to use a transponder with G.709 capability, and
> appropriate optics.
...
> You didn't say what specific complexity puts you off amps, but if it's
> just "more kit" then this solution isn't really any better, and I doubt
> much cheaper, than a pair of 9dB amps.

Hadn't thought of the G.709 angle. But since it still requires external
equipment (for a 6500) the amplification path is probably easier.

--
Peter


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