Quick facts about fibre standards

I don’t get to mess around with fibre a lot so I found the different standards and when to use what quite confusing. I’m doing a project right now where I need to connect two 3560 switches to a 3550. The 3550 uses a Gigabit Interface Converter (GBIC). We’re doing Single Mode (SM) so a 1000BASE-LX/LH GBIC will be used. In two sentences I have already used a lot of acronyms. The GBIC slides into one of two slots in the Cisco 3550. It looks like this:

Single mode refers to that there is only one path available in the core of the fibre but multi mode has several, this makes single mode useful for longer distances. The connector that fits with this GBIC is the Subscriber Connector (SC). It looks like this:

The SC connector is larger than the Lucent Connector (LC) that is used for Small Form-factor Pluggable (SFP). A SFP looks like this:

To connect to the SFP we will use the LC connector which is smaller than SC, SC won’t fit in a SFP. A LC connector looks like this:

There are a lot of different fibre cables with different connectors. To connect the two 3560’s a LC – LC cable will be used since both use SFP. When connecting to the 3550 which uses a GBIC a LC – SC cable will be used. So although there are a lot of standards the most used will be LC and SC. Another acronym you will run in to when shopping for fibre is Low Smoke Zero Halogen (LSZH) which means that the cable should be Halogen free and not develop smoke in case of a fire.

Another aspect is if to use simplex or duplex cable. Simplex means one cable and duplex means two. If you are in a LAN environment you will most likely use duplex. There is also different degrees of polish on the connectors. There is Physical Contact (PC) and variants of this like Super Physical Contact (SPC) and Ultra Physical Contact (UPC). Angled Physical Contact (APC) is another standard that is mostly used for Cable Television (CATV) networks.