we are moving a router between 2 data centers and we only have LX sfp's for connection, is there any issue using LX sfp's in a short range deployment ?
On Wed, Jan 25, 2012 at 2:26 PM, jon Heise <jon@smugmug.com> wrote:
we are moving a router between 2 data centers and we only have LX sfp's for connection, is there any issue using LX sfp's in a short range deployment ?
A Cisco 1000BASE-LX optic has the following spec: http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product_dat... -3dBm maximum transmit power, -3dBm maximum receive. That means you can run it over any length. (We use LX for everything.) -- Tim:>
Theoretically speaking Yes there should be an issue while using the LX SFP for short range because it may damage the receiver part. But we've been using it for quite a long time within datacenter for rack to rack switch connectivity without harming the SFP or the performance. Regards, Aftab A. Siddiqui On Thu, Jan 26, 2012 at 12:45 AM, Tim Durack <tdurack@gmail.com> wrote:
On Wed, Jan 25, 2012 at 2:26 PM, jon Heise <jon@smugmug.com> wrote:
we are moving a router between 2 data centers and we only have LX sfp's for connection, is there any issue using LX sfp's in a short range deployment ?
A Cisco 1000BASE-LX optic has the following spec:
http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product_dat...
-3dBm maximum transmit power, -3dBm maximum receive. That means you can run it over any length. (We use LX for everything.)
-- Tim:>
I can confirm using LX SFP's for under 100' runs with no problems. Except for the one site that ordered Multi-Mode fiber... Andrew On 1/26/2012 12:27 AM, Aftab Siddiqui wrote:
Theoretically speaking Yes there should be an issue while using the LX SFP for short range because it may damage the receiver part. But we've been using it for quite a long time within datacenter for rack to rack switch connectivity without harming the SFP or the performance.
Regards,
Aftab A. Siddiqui
On Thu, Jan 26, 2012 at 12:45 AM, Tim Durack<tdurack@gmail.com> wrote:
On Wed, Jan 25, 2012 at 2:26 PM, jon Heise<jon@smugmug.com> wrote:
we are moving a router between 2 data centers and we only have LX sfp's for connection, is there any issue using LX sfp's in a short range deployment ?
A Cisco 1000BASE-LX optic has the following spec:
http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product_dat...
-3dBm maximum transmit power, -3dBm maximum receive. That means you can run it over any length. (We use LX for everything.)
-- Tim:>
vendors that specify a minimum distance for lx typically spec 2 meters. even EX shouldn't spike the receiver at that distance as long as the max RX is about +1. On 1/25/12 11:26 , jon Heise wrote:
we are moving a router between 2 data centers and we only have LX sfp's for connection, is there any issue using LX sfp's in a short range deployment ?
You can put a 3dB or 5dB optical pad on the link if the receiver can't handle zero-distance optical power. On Thu, Jan 26, 2012 at 3:03 AM, Joel jaeggli <joelja@bogus.com> wrote:
vendors that specify a minimum distance for lx typically spec 2 meters.
even EX shouldn't spike the receiver at that distance as long as the max RX is about +1.
On 1/25/12 11:26 , jon Heise wrote:
we are moving a router between 2 data centers and we only have LX sfp's for connection, is there any issue using LX sfp's in a short range deployment ?
2012/1/26 David Storandt <dstorandt@teljet.com>
You can put a 3dB or 5dB optical pad on the link if the receiver can't handle zero-distance optical power.
We're using SFP LX for a couple of years even in back to back configuration for equipments within the same rack with a 1 meter patch cord without any problem. Max TX is -3dBm, Max RX sensivity is -3dBm so there is no problem. 1. I don't think I've ever had a LX SFP that TX at -3 dBm, they're usually around -5 to -7 dBm. and example in a live router : pymaunier@re1.tcr1.rb.par> show interfaces diagnostics optics ge-7/3/* | match "Laser output power " Laser output power : 0.3160 mW / -5.00 dBm Laser output power : 0.1800 mW / -7.45 dBm Laser output power : 0.2600 mW / -5.85 dBm Laser output power : 0.3210 mW / -4.93 dBm Laser output power : 0.3070 mW / -5.13 dBm Laser output power : 0.3200 mW / -4.95 dBm Laser output power : 0.3180 mW / -4.98 dBm Laser output power : 0.3140 mW / -5.03 dBm 2. You can assume a patch cord add between 0.2 to 0.5 dB of attenuation so even with a SFP TX at -3dBm, you won't receive at the Max RX sensitivity. -- Pierre-Yves Maunier
Awesome, i got some single mode LC LC fiber off monoprice, sounds like i should be all set for this. Thanks for everyones info - Jon On Thu, Jan 26, 2012 at 6:24 AM, Pierre-Yves Maunier <nanog@maunier.org>wrote:
2012/1/26 David Storandt <dstorandt@teljet.com>
You can put a 3dB or 5dB optical pad on the link if the receiver can't handle zero-distance optical power.
We're using SFP LX for a couple of years even in back to back configuration for equipments within the same rack with a 1 meter patch cord without any problem.
Max TX is -3dBm, Max RX sensivity is -3dBm so there is no problem.
1. I don't think I've ever had a LX SFP that TX at -3 dBm, they're usually around -5 to -7 dBm.
and example in a live router :
pymaunier@re1.tcr1.rb.par> show interfaces diagnostics optics ge-7/3/* | match "Laser output power " Laser output power : 0.3160 mW / -5.00 dBm Laser output power : 0.1800 mW / -7.45 dBm Laser output power : 0.2600 mW / -5.85 dBm Laser output power : 0.3210 mW / -4.93 dBm Laser output power : 0.3070 mW / -5.13 dBm Laser output power : 0.3200 mW / -4.95 dBm Laser output power : 0.3180 mW / -4.98 dBm Laser output power : 0.3140 mW / -5.03 dBm
2. You can assume a patch cord add between 0.2 to 0.5 dB of attenuation so even with a SFP TX at -3dBm, you won't receive at the Max RX sensitivity.
-- Pierre-Yves Maunier
I have found that -5dB or -10dB attenuators must be used on the send or receive strands between Cisco LX connected switches at relatively short distances of < 1 km over standard singlemode fiber. Other Vendors' SFPs rated up to 25 km do not need attenuators at distances <1 km. -----Original Message----- From: Jon Heise [mailto:jon@smugmug.com] Sent: Thursday, January 26, 2012 9:41 AM To: Pierre-Yves Maunier Cc: nanog@nanog.org Subject: Re: LX sfp minimum range Awesome, i got some single mode LC LC fiber off monoprice, sounds like i should be all set for this. Thanks for everyones info - Jon On Thu, Jan 26, 2012 at 6:24 AM, Pierre-Yves Maunier <nanog@maunier.org>wrote:
2012/1/26 David Storandt <dstorandt@teljet.com>
You can put a 3dB or 5dB optical pad on the link if the receiver can't handle zero-distance optical power.
We're using SFP LX for a couple of years even in back to back configuration for equipments within the same rack with a 1 meter patch cord without any problem.
Max TX is -3dBm, Max RX sensivity is -3dBm so there is no problem.
1. I don't think I've ever had a LX SFP that TX at -3 dBm, they're usually around -5 to -7 dBm.
and example in a live router :
pymaunier@re1.tcr1.rb.par> show interfaces diagnostics optics ge-7/3/* | match "Laser output power " Laser output power : 0.3160 mW / -5.00 dBm Laser output power : 0.1800 mW / -7.45 dBm Laser output power : 0.2600 mW / -5.85 dBm Laser output power : 0.3210 mW / -4.93 dBm Laser output power : 0.3070 mW / -5.13 dBm Laser output power : 0.3200 mW / -4.95 dBm Laser output power : 0.3180 mW / -4.98 dBm Laser output power : 0.3140 mW / -5.03 dBm
2. You can assume a patch cord add between 0.2 to 0.5 dB of attenuation so even with a SFP TX at -3dBm, you won't receive at the Max RX sensitivity.
-- Pierre-Yves Maunier
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-----Original Message----- From: Jon Heise Sent: Thursday, January 26, 2012 9:41 AM To: Pierre-Yves Maunier Cc: nanog@nanog.org Subject: Re: LX sfp minimum range
Awesome, i got some single mode LC LC fiber off monoprice, sounds like i should be all set for this. Thanks for everyones info
- Jon
SX can actually be a little more versatile. LX works only over single mode fiber. SX is designed to work over either. As long as you have SX at both ends, you can connect them with either single or multimode fiber as long as the fiber type is consistent over the entire run.
2012/1/26 George Bonser <gbonser@seven.com>
SX can actually be a little more versatile. LX works only over single mode fiber. SX is designed to work over either. As long as you have SX at both ends, you can connect them with either single or multimode fiber as long as the fiber type is consistent over the entire run.
It's the contrary. SX only works on multimode fibre, not on singlemode. LX can work on both. It can happends that SX works on singlemode but it can fail anytime. LX over multimode fibre is documented on Cisco SFP/GBICs datasheets. http://www.cisco.com/en/US/products/hw/modules/ps4999/products_tech_note0918... Cisco 1000BASE-LX/LH SFPGLC-LH-SM1SFP-GE-L2Operates on standard single-mode fiber-optic link spans of up to 10 km and up to 550 m on any multimode fibers. -- Pierre-Yves Maunier
In some enterprise applications, SX is "good enough" for the distances at hand, and SX optics are cheap... On Thu, Jan 26, 2012 at 3:33 PM, Pierre-Yves Maunier <nanog@maunier.org>wrote:
2012/1/26 George Bonser <gbonser@seven.com>
SX can actually be a little more versatile. LX works only over single mode fiber. SX is designed to work over either. As long as you have SX
at
both ends, you can connect them with either single or multimode fiber as long as the fiber type is consistent over the entire run.
It's the contrary. SX only works on multimode fibre, not on singlemode.
LX can work on both.
It can happends that SX works on singlemode but it can fail anytime.
LX over multimode fibre is documented on Cisco SFP/GBICs datasheets.
http://www.cisco.com/en/US/products/hw/modules/ps4999/products_tech_note0918...
Cisco 1000BASE-LX/LH SFPGLC-LH-SM1SFP-GE-L2Operates on standard single-mode fiber-optic link spans of up to 10 km and up to 550 m on any multimode fibers.
-- Pierre-Yves Maunier
On 01/26/12 16:33, Pierre-Yves Maunier wrote:
LX can work on both.
It can happends that SX works on singlemode but it can fail anytime.
LX over multimode fibre is documented on Cisco SFP/GBICs datasheets.
http://www.cisco.com/en/US/products/hw/modules/ps4999/products_tech_note0918...
Cisco 1000BASE-LX/LH SFPGLC-LH-SM1SFP-GE-L2Operates on standard single-mode fiber-optic link spans of up to 10 km and up to 550 m on any multimode fibers.
just because you can doesn't mean you should. we have experience multiple cases where LX-MMF-LX works great for 3-5+ years... then one day no longer gets link. swapping to a different fiber pair restores link. can't remember SX-MMF-SX failing after years of service. -- Steven Tardy Systems Analyst Information Technology Infrastructure Information Technology Services Mississippi State University sjt5@its.msstate.edu
2012/1/27 Steven Tardy <sjt5@its.msstate.edu>
On 01/26/12 16:33, Pierre-Yves Maunier wrote:
It can happends that SX works on singlemode but it can fail anytime.
just because you can doesn't mean you should.
we have experience multiple cases where LX-MMF-LX works great for 3-5+ years... then one day no longer gets link. swapping to a different fiber pair restores link. can't remember SX-MMF-SX failing after years of service.
That's why I wrote 'but it can fail anytime' meaning, I strongly recommand to NOT do it. -- Pierre-Yves Maunier
I once tried an LX-SMF-MMF-LX type setup using mode conditioning patch leads between the SMF-MMF and MMF-LX portions of the span. I would be hesitant to recommend it, simply touching the patch lead on the MMF-LX portion would result in horrendous error counts. Suffice to say, we bit the bullet and got some SMF blown through (tubes ftw). I have also used LX-LX on short SMF runs of a couple of metres, for 1G and 10G, with no issues. On 27 January 2012 16:47, Pierre-Yves Maunier <nanog@maunier.org> wrote:
2012/1/27 Steven Tardy <sjt5@its.msstate.edu>
On 01/26/12 16:33, Pierre-Yves Maunier wrote:
It can happends that SX works on singlemode but it can fail anytime.
just because you can doesn't mean you should.
we have experience multiple cases where LX-MMF-LX works great for 3-5+ years... then one day no longer gets link. swapping to a different fiber pair restores link. can't remember SX-MMF-SX failing after years of service.
That's why I wrote 'but it can fail anytime' meaning, I strongly recommand to NOT do it.
-- Pierre-Yves Maunier
On Thu, Jan 26, 2012 at 13:47, David Storandt <dstorandt@teljet.com> wrote:
You can put a 3dB or 5dB optical pad on the link if the receiver can't handle zero-distance optical power.
As I recall, the problem may not only be the power (which can cause receiver saturation), but issue that fibre paths shorter than (around) 2-10m do not properly condition the light(*), which can result in some issues at the receiver. Gary (*) My memory says modal distribution issues. While 'single mode' fibre only supports one mode of transmission, it takes a short distance for the fibre to really be single mode. You can use a mode filter to address the problem, or just use fibres that are at least a few meters.
On Thu, Jan 26, 2012 at 10:48:05PM +0000, Gary Buhrmaster wrote:
On Thu, Jan 26, 2012 at 13:47, David Storandt <dstorandt@teljet.com> wrote:
You can put a 3dB or 5dB optical pad on the link if the receiver can't handle zero-distance optical power.
As I recall, the problem may not only be the power (which can cause receiver saturation), but issue that fibre paths shorter than (around) 2-10m do not properly condition the light(*), which can result in some issues at the receiver.
Gary
(*) My memory says modal distribution issues. While 'single mode' fibre only supports one mode of transmission, it takes a short distance for the fibre to really be single mode. You can use a mode filter to address the problem, or just use fibres that are at least a few meters.
When optics started to become scarce at various times, I've done a number of back-to-back connections using SM fiber and have had zero issues. I wouldn't even worry about it. Remember, many carriers won't even touch MM and they aren't chronically reporting issues or going to lengths to work around them. -Wayne --- Wayne Bouchard web@typo.org Network Dude http://www.typo.org/~web/
participants (15)
-
Aftab Siddiqui -
Andrew D Kirch -
David Storandt -
Gary Buhrmaster -
George Bonser -
Holmes,David A -
Joel jaeggli -
jon Heise -
Jon Heise
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PC -
Pierre-Yves Maunier -
Steven Tardy -
Tim Durack -
Tom Storey -
Wayne E Bouchard