Single-mode to Multi-mode

[force5]

Good morning...If single mode fiber has been ran all the way up to and terminated on the patch panel, can we then use a multi-mode patch cable from the patch panel to the switch (Cisco 2940) and into the SFP (GLC-LH-SM)?

Thank you

Thanks,

Chad
Network Administrator

 

[unclerico]

no. you need a mode conditioning patch cable

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[force5]

Thanks unclerico,

I have a 6 foot LC to ST Mode Conditioner cable (multi-mide 62.5)but some of my research showed that it wouldn't work. So, are you saying that as long as all of my patch cables are mode conditioning, they will work fine regardless of single mode or multi mode? We have lots of different fiber types ran throughout the refinery, and I would love to make this as easy as possible, all while maintaining consistency.

Oh, also, someone told me that the type of patch cable also depends on whether it is coming from a patch panel or from another switch's SFP (trunk port)...is this true, or doesnt that matter?

Thanks a million!

Chad

Thanks,

Chad
Network Administrator

 

[unclerico]

why not just use a single-mode patch cable from the panel to the switch??

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[MrOyvind]

CRC and Input errors is my experience with SM fiber and MM SFP and MM fiber.
Users was frustrated after fixing some old things. The applications worked sometimes and sometimes not.

Oyvind

 

[force5]

Thanks for the input...I do have the correct single mode patch cables shipping here tomorrow. The frustrating thing is that we have a wide variety of fiber throughout the facility. We use single-mode, multi-mode, and hybrid. I was just hoping on not having to rely on all of the different types of patch cables, SFPs, etc....was hoping to make things a little simpler.
So, to clarify:
If single-mode is run to the back of the patch panel, then it is BEST to use a single-mode patch cable
If multi-mode is run to the back of the patch panel, then it is always best to use a multi-mode patch cable
And as far as SFPs, as long as I follow Cisco's SFP matrix, I'll be fine?

http://www.cisco.com/en/US/docs/int...ver_modules/compatibility/matrix/OL_6981.html

And one final question (thanks for your help) does the same apply when running fiber from switch1's SFP to switch2's SFP? For example, if I just want to extend fiber out to a 2nd building that is very close in distance, and switch1 is connected via single mode fiber, do I need to use a single mode jumper to run to switch2's SFP?

Thanks guys!

Chad

Thanks,

Chad
Network Administrator

 

[MrOyvind]

If single-mode is run to the back of the patch panel, then it is BEST to use a single-mode patch cableIf multi-mode is run to the back of the patch panel, then it is always best to use a multi-mode patch cable

Yes

And not use singele mode SFP on very short distances, it will burn out the SFP at the other end.

Oyvind

 

[VinceWhirlwind]

Basically, your SFPs are your active components.

To make a successful connection, the active components must match, (eg, SX-SX or LH-LH).

The passive components in the path of the connection must:
- match the active components (eg, OM3 cable with SX, singlemode with LH)
AND
- must all be the same in any one connection (eg, between any two SFPs, ALL patch cables/strctured cabling must be OM3, or ALL must be singlemode).

If you use OM3 patch leads on either end of a singlemode structured cabling, you will get a link light, but as soon as you put traffic on the link, you will get a large error rate.

 

[force5]

Thanks for the explanations! VinceWhirlwind, you mention, "The passive components in the path of the connection must: - match the active components (eg, OM3 cable with SX, singlemode with LH)" I have been planning on using GLC-LH-SM-CX SFP's in 2960G (WS-C2960G-24TC-L) regardless of multi-mode or single-mode...I was told that the GLC-LH-SM-CX SFP can work with either single or multi, is this true?

Thanks

Thanks,

Chad
Network Administrator

 

[VinceWhirlwind]

Your fibre patch leads have to be the same grade of fibre as the structured fibre cabling they patch from.

I wouldn't waste an LH SFP on multimode fibre - they cost twice as much as SXs. The only time you might do it is if you have a longer run of fibre and your SX SFPs aren't doing the job properly.