What cable do I need to connect two switches using SFP GLC-SX-MM GBIC's?

[tjackson]

What cable do I need to connect two 3560 catalyst switches using these interfaces? I attached a picture of the interfaces I want to use.

[Mirko Grabel]

Hi,

regarding Fibre cables there are basically 2 important tricks:

1. The Connectors.     The types "SC" and "LC" exist. SC is the older and bigger connnector, LC is the smaller and newer one.

                              As you use SFPs you need the LC Connector on both ends (I assume you have a direct connection and no patch panel in the middle?)

2. The Cable.      Here exist also just 2 mayor differences:

                    MultiMode (bigger fibre, cheaper, for SHORT connections (depending on SFP type up to a couple of hundred meters.)

                    SingleMode (smaller fibre, more expensive, depending on SFPs multiple Kilometres (I think 80 is max).

                    As you have the "MM" type SFP, you need a MultiMode cable.

There are also subcategories in SM and MM cables depending on "how clear" the cables are, but that does normally just matter in the really long range SR area.

So in short: go for a LC <-> LC MultiMode cable ;-)

[tjackson]

ok, these switches are going to be right next to each other in the exact same rack. What is the least expensive option that I can use that will still give me 1gbps connectivity?

[Leo Laohoo]

ok, these switches are going to be right next to each other in the exact same rack. What is the least expensive option that I can use that will still give me 1gbps connectivity?

If your 3560 are the non-"G" model than your only choice is using 1G SFP modules and connecting them together using LC-LC cable (of appropriate length, of course).

[Nathan Spitzer]

As has been noted you have multi-mode SFP's so you have to use Multimode fiber with LC connectors on each end.

There are 3 grades of MM fiber:

• OM1 - 62.5/125 (core/cladding) also known as FDDI grade. Is almost alway orange unless its REALLY old (I have some gray laying around). I am highly recommending internally that my organization NOT use this grade anymore. The 80's and 90's are calling and want their fiber back.
  
• OM2 - 50/125 (core/cladding). This is a better grade and normally costs no more then 62.5 and like OM1 and is almost always orange.It increases the range of 1GB/s MM.
• OM3 - 50/125 (core/cladding). This is a vastly superior version of OM1 and a marked improvement over OM2. It vastly increases the distance of 10GB. Internally I specify all new sites (and all new fiber runs) be OM3.

Save money by buying from an electrical supply house like Graybar instead of Staples and get at least OM2. Will it make a difference for what you are doing now? No but its a good habit to get into. BTW  while theoretically you should mix-n-match even Cisco has documented no ill effects from mixing OM3 patch cables to OM1 internal runs though of course you are limited to OM1 distances and I would not try it with long-distance 10GB.

Amazon has a OM3 patch cable 5 meters long for $22: http://www.amazon.com/16-4ft-mSFP-LC-Duplex-Multimode-Brocade/dp/B0044ZC2CG/ref=sr_1_7?ie=UTF8&qid=1294347490&sr=8-7

[Leo Laohoo]

The fibre optic cable type is known as a "LC to LC" cable.

You have the option of choosing how "thick" the glass are.  We are currently using the thicker OM3. 

[Nathan Spitzer]

Actually OM3 is thinner the OM1 (50nm versus 62.5nm) with the same 125nm cladding and is the same physical size as OM2. The difference between OM2 and OM3 is that the glass used in OM3 is of much higher quality to minimize modal dispersion and maximize distance for the higher-speed lasers used in 10GB applications.

[Leo Laohoo]

Thanks for the correction Nathan.

[tjackson]

So would something like this work:

http://cgi.ebay.com/LC-LC-fiber-patch-jumper-cable-cord-MM-duplex-1M-/270401056135?pt=LH_DefaultDomain_0&hash=item3ef528ad87

[Mirko Grabel]

Yes

[c.j.sparrow1988]

hi...
i have the same question as the original poster, that's why i'm posting here . . .

when we talk about the kind of cable to use there are several factors involved:

1. whether or not the cable is multi mode or single mode . . .

2. the type of the multi mode (or single mode - which is not the case here) cable like : FDDI, OM1, OM2, OM3 etc . . . .

3. whether or not a patch panel is necessary . . .

4. the type of the patch cord and if a mode conditioning patch cord is necessary . . .

5. the type of the connectors: LC, SC etc.

6. the number of optical fiber cores in the cable . . .

my question is specifically the last one: the number of cores! i have no idea what the difference is between a 4 core and a 24 core cable and which one should be used with a 1000BASE-SX SFP . . . .

to my knowledge an SX transceiver module has two ports, one for Rx and one for Tx . . . does it mean that the optical cable should at least have two cores or should we use two separate optical cables ? what about a 24 core cable ? what happens to all those 22 extra cores ?

I'd be grateful if someone could shed some light on this problem . . .

TIA.