SAN over single-mode FC cabling

[toomas_aas]

Hello!

We are beginning to deploy a SAN in our organization. We have two buildings where the SAN -connected devices should be located. Between buildings we have single-mode fiber-optic cable (300 m). It seems that standard SAN components, however, all use multi-mode cabling. Is it possible to use our single-mode fibre for SAN (using, for example, some kind of media converters)?

We also have alternate path between buildings which is using multi-mode cable, but it's length is 550 m, which seems to be just a bit too long for even 1 Gbps speed...

[Mark Poeschl_2]

The specs for the standard short-wave GBIC in the FC switches list 500m as the maximum length so I think you should be good to go with the single mode fibre. Worst case, you could install long-wave GBICs in the switches for the inter-building links.

[Jonathan Harris_3 · Accepted solution]

Check the specs and compatibility of your fibre connectors.

In the case of Cisco, using singlemode fibre (SMF) is possible if you use longwave SFPs at each end of the connection. Trying to connect SMF to standard connections won't work as standard shortwave SFPs only support multimode fibre.

[toomas_aas]

Thanks for your replies, folks. I understand that using standard (cheaper) short-wave SFPs things *might* work over the 550m multimode cable, but using long-wave SFPs over the single-mode cable is a sure bet. Correct?

[Jonathan Harris_3]

Pretty much. Running your traffic over 550m MMF might work, but I'd be uncomfortable transmitting any data over an unsupported medium.

By the way, to even get close to 500m, you need to check the core size and baud rate for your MMF - 50 micron / 1.0625 GBd will gives a theoretical maximum of 500m, but others only support 300m.

Longwave SFPs with SMF are the way forward, I would suggest.

[Peter Mattei]

Why do you not just purchase Long Wave SFPs?
These are designed and fully supported for single mode 9um fibre cables.
See the SAN Design Reference Guide for your respective switch brand (Brocade Chapter 4 or Cisco Chapter 5)

http://www.hp.com/go/sandesign

Also see here for information: http://h18006.www1.hp.com/storage/networking/index.html

Cheers
Peter

[toomas_aas]

I wasn't saying I'm not going to buy long-wave equipment. Just tried to make sure I understood everything right.

[sanzende]

Hi,

Can we connect longwave SFP using multimode fiber cable ?

[Uwe Zessin]

Physically connect? yes.

Does it work reliably? Maybe on a short distance, but the signal characteristics single vs multi just do not fit.

Please do yourself a favour and do not mix single-/multi-mode components in one data path. Otherwise it could 'bite' you back one day.

[sanzende]

Thanks Uwe Zessin!!

I have one more doubt.

What is the difference between the dark fibre optic cable and the single mode fibre optic cable ?

Thanks Again!!