Which SFP Module for Fiber

charold

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Sep 7, 2011
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I am working at a new site as of Dec 2014. I am doing some much needed network infrastructure upgrades, and am having trouble determining which SFP Module to buy for a Catalyst 2960s. This fiber was originally put in awhile ago (15years ago to be exact), and I believe I have the right module needed, but wanted a second opinion.


The only real documentation I have is this

62.5mm Fiber - outdoor loose - 1600ft distance

This leads me to believe I'm looking at 1000BASE-LX, in which case I'm looking at this module
1000base-lx-lh

The odd thing, maybe someone can clear up, is I have a mix of SMF and MMF patch cables from the fiber patch panel to my switches right now. I'm not sure how that works, since it's all the same fiber runs. Either way, any help is appreciated. Thanks!
 

mwarps

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You need to know what ends are on the fiber.

Post a picture.
 

epimetheus

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First, it's 62.5um, not mm. That refers the the size of the fiber core, thus mm is an unreasonable dimension. 62.5um and 50um fiber are multi-mode. 1000BASE-LX uses single-mode fiber, thus not a match to your installed fiber. 1000BASE-SX is the standard for gigabit over multi-mode fiber and is spec'ed for 220m over 62.5um fiber and 550m over 50um fiber.
 

charold

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There are two different types of patch cables


SM ST to MM LC Mode Coditioning Fiber Patch Cable that look like the below


ST-LC Fiber Patch Cable SM


Photos of setup
 

charold

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First, it's 62.5um, not mm. That refers the the size of the fiber core, thus mm is an unreasonable dimension. 62.5um and 50um fiber are multi-mode. 1000BASE-LX uses single-mode fiber, thus not a match to your installed fiber. 1000BASE-SX is the standard for gigabit over multi-mode fiber and is spec'ed for 220m over 62.5um fiber and 550m over 50um fiber.

I understand that, I am quoting from the little documentation I have. Verbatim its "12 fiber 62.5mm outdoor loose" at 1600ft. I'm assuming mm is multimode.
 

bds1904

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62.5 is multimode fiber. The sfp you have linked is for singlemode. If you had singlemode fiber is would say 8.3/125 on it.

In short you need a sfp designed for multimode fiber with the appropriate connectors based on what is on the fiber.

http://www.thefoa.org/tech/connID.htm

As others have stated, you won't be getting over 100mbps on the fiber, it's too long and too large for 1000mbps. At 1600ft I would pull 8.3/125 singlemode so it would be good for 10Gbps.
 
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charold

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62.5 is multimode fiber. The sfp you have linked is for singlemode. If you had singlemode fiber is would say 8.3/125 on it.

In short you need a sfp designed for multimode fiber with the appropriate connectors based on what is on the fiber.

http://www.thefoa.org/tech/connID.htm

As others have stated, you won't be getting over 100mbps on the fiber, it's too long and too large for 1000mbps. At 100ft I would pull 50/125 multimode om3 so it would be good for 10Gbps.

Oops, I linked the wrong one!

Proper Module I was looking at
 

epimetheus

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Mode conditioning patch cables are used for connecting single-mode optics (such as 1000LX) to a multi-mode fiber system. If your installed fiber (connected to the back of the patch panel) is multi-mode, you shouldn't have yellow (single-mode) patch cables connected to the front.

Edit: Keep in mind that 1600' is over the 1000SX spec'ed limit for gigabit on 62.5um fiber (220m). Probably why MCP cables (mode-conditioning patch cables) are in use, though I can't find any guidelines for range calculations with MCP's.
 
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charold

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Mode conditioning patch cables are used for connecting single-mode optics (such as 1000LX) to a multi-mode fiber system. If your installed fiber (connected to the back of the patch panel) is multi-mode, you shouldn't have yellow (single-mode) patch cables connected to the front.

Edit: Keep in mind that 1600' is over the 1000SX spec'ed limit (220m) for gigabit on 62.5um fiber.


Switche states it's running at a Gb, whatever that is worth.... I'm calling the up the vendors that have done work on it last, and seeing if I can get any clarification/information on what is actually run, and make my determination from there.
 

charold

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After looking into this more, it looks like the fiber was replaced in 2011 with SMF. I'm talking to the other vendors, and getting additional details. Being 2011, it may be 9um cables! This is starting to make a lot more sense. I'm a little new to the fiber world, so I appreciate the input.
 
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charold

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Wow, the story gets deeper. There were 2 Plants, P2 and P3 originally, with 62.5um MM fiber running between them, 1600ft total. They added another plant, P1, spliced in the 62.5um MM fiber connecting

P1<--1300ft-->P2
and
P1<--1400ft-->P3

There was a break between P1 <--> P3, compromising all fiber. This was then upgraded to 9um SM fiber. So in the back of my fiber patch panel I have both 62.5um MM and 9um SM fiber terminating to it, with no documentation whatsoever (why make my job easy?).

This would explain both SM, SM-MM conditioning cables, and straight MM fiber patch cables.

From what I can see, using a 1300-nm optics on the 62.5MM fiber achieves Gb speeds at up to 550m. I believe this is what were using for P1 - P2. Does anyone know how I can go about confirming this, pulling the SPF module out of the switch and looking up the specs is the only idea I have?
 

green91

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Just use the Singlemode with 1000LX optics. This will give you 12km distance and you wont have to worry about the quality of the splice work from the broken fiber. 62.5 is OM1 typically which is the oldest variant of multimode around.

To check your current sfp type, many cisco switches will tell you 1000sx/lx with a simple show interface <int> command.
 

charold

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Maybe this will help someone in the future, reading further into Cisco docs it looks like as long as you are using mode conditioning cables, you are set to go. All the newer SFPs look to use 1300nm optics, which requires the use of the conditioning cables.

Overview of SFP

Mode Conditioning Cables


I am only upgrading the switches connected through SMF, so ironically the improper linked item at the top is the one I got.
 

green91

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I disagree; multimode optics aren't going anywhere. The only time you want to use mode conditioning cables is to get a slightly longer distance over MMF with single mode optics. 1000SX and 10Gb-SR aren't go anywhere. OM3/OM4 is pretty much the standard for intra-building fiber connections.

BTW, single mode is usually 1310 or 1550, not 1300nm.
 

charold

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I disagree; multimode optics aren't going anywhere. The only time you want to use mode conditioning cables is to get a slightly longer distance over MMF with single mode optics. 1000SX and 10Gb-SR aren't go anywhere. OM3/OM4 is pretty much the standard for intra-building fiber connections.

BTW, single mode is usually 1310 or 1550, not 1300nm.

I'm not sure who you are disagreeing with? I should have been more clear, but yes the 1300nm is for the MMF, which I am not touching at the moment, so no changes are/need to be made ATM.
 

epimetheus

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Welcome to the fiber jungle, we've got fun and games...

Glad you got it sorted. I run into this confusion and poor documentation often with fiber in plants and electrical substations.
 

green91

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I'm not sure who you are disagreeing with? I should have been more clear, but yes the 1300nm is for the MMF, which I am not touching at the moment, so no changes are/need to be made ATM.

I was disagreeing with the comment that all newer SFP optics are 1300nm.
 
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