Mid-range SFP options

[darren.g]

Gentlemen and optical experts.

I've been put in a bit of a quanrdy by geography, and I need some input from those with more expertiese than I.

My place of employ is putting a dark fibre between our DC and a client site, and we've just gotten back the estimate for the cable distance fromt he dark fibre company - and it's not good.

The estimated distance buolding to building - and that's to the street demarc point, not necessarily to our kit - is 9.8 kilometers (9800 meters).

Now, GLC-LH-SM SFP's are rated to 10000 meters on single mode fiber - but that leaves me with *damn* little margin for demarc-to-rack cabling (100 meters each end), which likely isn't going to be enough.

Cisco's web page lists an EX series of SFP - GLC-EX-SMD - which is rated to 40000 meters - but I can't for the life of me find out if

     1) These SFP's are still in production/available

     2) They're supported by my switches (WS-C3750X on one end and WS-C2960 on the other)

The next option is the long reach SFP - GLC-ZX-SM - but these are hideously expensive, and my boss freaked when I pointed out we may have to buy them. And both these longer range types mention needing an attenuator on each end - which scares me a bit, because I know nothing about them.

So, my questions to the learned are

     A) Has anyone ever successfully pushed an LH type SFP more than 10000 meters? If so, how far? How likely am I to be able to manage it

     B) Does anyone know if the EX-series SFP's are still available, and if they are, are they supported by the switches listed above?

     C) If I need to go to the EX or ZX series SFP's, how do these attenuators work, and do I need to look at specific types/strengths?

Thanks in advance.

[Joseph W. Doherty]

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Posting

     C) If I need to go to the EX or ZX series SFP's, how do these attenuators work, and do I need to look at specific types/strengths?

They diminish the light's strength, like having additional fiber.  Found the following somewhere, I recall, on Cisco's web site:

• You must insert a 10-dB inline optical attenuator between the single-mode fiber-optic network and the receiving port on the 1000BaseZX GBIC at each end of the link if the link length is less than 15.5 miles (25 km).
• You must insert a 5-dB inline optical attenuator between the single-mode fiber-optic network and the receiving port on the 1000BaseZX GBIC at each end of the link if the link is greater than 15.5 miles (25 km), but less than 31 miles (50 km).

[darren.g]

Joseph.

Seems the EX series of trancievers are not available (or supported) by the switches I want to use, so I've had to go with the ZX.

Thanks for the hints regarding the attenuator size - I've found somewhere local to buy them, and they're not as hideously expensive as I expected them to be, so I should be sweet.

D*mn, there's a difference in price between the LX/LH and ZX tranceivers, though!! :-)