My provider said they can provide single / mulit mode Optical fiber

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Apart from the length and cost different, what is the Adv/Disadv between them for our connection?

The advantages are always in the distance capabilities of the single mode fiber. You can reach much further on this, but the optics tend to be more expensive. If you are going a short distance (eg: 2km or less) multi-mode is the way. If you're going to go any further, or want to ever go any further, take the extra cost and know you can swap optics in the future to do gig, 10G and possibly more (in the future) with less pain.

Just to amplify Jared's very complete answer. The principle reason you would use multimode instead of single mode is reduced cost. If cost isn't an issue, single mode has more potential to be used in more applications. Even the longer range SM optics can be used for short range uses with inexpensive attenuators. Service Providers support both because their customers may only support one or the other. Deepak Jain AiNET

Wanted to add something to this and clarify/correct a few points:

Plus, while I'm sure someone in a lab has done it, you really don't run DWDM over multimode fiber - I'd second the opinion of it's cheap enough, go for the single mode and get the most flexibility in your options possible.

In fact, already being done - this is how 10GB-LX4 operates. The point here is that each of the four channels operates at less than 10 gigabits/sec, and that MMF didn't prevent it, in fact, it was done entirely to make 10 gig work over MMF. Caveats include mode-adapter cables and other funk to interface LX4 to mmf. Long-reach single-carrier (ie. single optical channel/frequency) 10 gig over MMF salso has a 'spec' (10G-LRM), but I'm not personally familiar enough with vendors to offer anything useful or practical.

One minor consideration is usually SM optics are stronger, so don't forget attenuation if it's a short distance or you might burn out your pricey new optics!

I would invite folks to examine the various gradations of gig and 10 gig LR/ER/ZR devices. Pulled from a handy table at http://www.andovercg.com/datasheets/juniper-ethernet-pics.pdf, I submit for your consideration a summary of the powers across the various flavors of xenpak. Note the modest increases in launch power, while there are considerable and huge increases in sensitivity. 10-Gbps Gigabit Ethernet XENPAK, 1-port • XENPAK pluggable optics (SR, LR, ER, ZR types) • SR optical interface (IEEE 802.3ae compliant) – Average launch power: -4.5 through -1 dBm – Receiver saturation: -1.0 dBm – Receiver sensitivity: -7.5 dBm • LR optical interface (IEEE 802.3ae compliant) – Average launch power: -4 through 0.5 dBm – Receiver saturation: 0.5 dBm – Receiver sensitivity: -10.3 dBm • ER optical interface (IEEE 802.3ae compliant) – Average launch power: -4.7 through 4 dBm – Receiver saturation: 1 dBm – Receiver sensitivity: -11.3 dBm • ZR optical interface (IEEE 802.3ae compliant) – Average launch power: 0 through 4 dBm – Receiver saturation: -7 dBm – Receiver sensitivity: -24 dBm -tk

On 11/12/2009, at 4:58 AM, Jared Mauch wrote:

You can reach much further on this, but the optics tend to be more expensive. If you are going a short distance (eg: 2km or less) multi-mode is the way.

I can buy LH GigE SFPs for AU$67 each, MM GigE SFPs for AU$61. AU$6 difference is really noise. Bring on Vendor equipment with SFP+ optic support for 10G - AU$1199 for 10G-LR SFP+! ($AU = Australian Dollar which is about US 91c) MMC -- Matthew Moyle-Croft Peering Manager and Team Lead - Commercial and DSLAMs Internode /Agile