Week 4: Day 012 - Cabling/Topology #3

Today, I will finish off the section on Cabling/Topology! So last week I left off on Twisted Pairs, CAT ratings and MHz (Megahertz) after thoroughly going through coaxial cables. Now, let's take a look at the other cables.

So next up is the Fiber-Optic cable (spelled Fibre-Optic in other English speaking countries) which is different from the cables before. This cable astounds me as it transmits LIGHT, rather than electricity! Crazy isn't it?! The problem here, is as usual, the amount of attractions for EMI. However, if you thought the astonishment would end there, you're wrong. This, unlike copper cables, can travel to distances up to 10 KILOMETERS! Again, that's pretty crazy. But how is this done? The make up of a fiber-optic cable according to my textbook is the "glass fiber"(the core), the "cladding" (this makes the light reflect down the fiber), the buffer (gives material strength), and the "insulating jacket". These cables are made with much variety in the core and cladding. Cable manufacturers use two-number designators to define those two elements of the cable. The most common size of the fiber-optic cables is 62.5/125 um (can't really do the symbol haha.) Most fiber-optic cables use pairs of fibers, one for sending the other for receiving. This is called "duplex fiber-optic cabling". This type of cabling is tiny, and there are two types that accept two different types of lighting. In my case, if I required a fiber-optic cable for networking (probably not) then I would use fiber optics that use LEDs (Light Emitting Diodes) to get the light signals across. Those types of cables are known as MMF (multimode fiber.) The other type is an SMF (Single-mode fiber) which uses lasers (cool!) and this type prevents a common issue with MMF's and that's "modal distortion", when signals sent at the same time don't arrive at the same time, because of differing cable lengths. The way these cables interpret the wavelengths of light is in nanometers (nm). MMF's transmit 950-nm wavelengths while the SMF transmits 1310 or 1550 nm, depending on which laser. Fiber-optic cables come in a variety of connector types. What is important to know for the Network+ exam is ST, SC, and LC (LC especially because of it's duplex connector which accepts two fiber cables.)

Wow, that was long! Don't worry the rest of the chapter may be a variety of cables, but not too much info. So first off is the "Classic Serial"  cabling, which is super ancient lol and it predates networking and PC's! RS-232 is the "recommended standard" in which serial communication took place on a PC. It hasn't changed much obviously, and when the PC came out they were the only standard. Because of these, companies like IBM put two ports for serial networking on every PC. You still find them on there to this day! The most common type is a "male" DB-9 which is a 9-pin serial port. Not surprisingly, nowadays serial networking is sucky and terrible. It has slow data rates of 56,000 bps (that's right BYTES per second) and only do point-to-point connections. Continuing, let's stay in the past. Now we have "Parallel" connections. The textbook literally characterizes this and serial networking as ancient haha (do you even remember this back in the day Mr. Elkner???). Anyways, this is also a limited point-to-point topology and uses a 25-pin "female" instead of a male DB connector. That's literally all to say for both serial and parallel. Now there's FireWire. This is the only good alternative cabling option to UTP or fiber-optic cables. It's again, restricted to point-to-point connections, but is actually very fast! It has its own connector as you could imagine. Going towards the end of my blog entry, let's start talking about standards. In terms of FireWire, the NEC (National Electrical Code) and the Underwriters Laboratories work together in making "fire ratings". The two common ones are PVC (polyvinyl chloride) and plenum. Cable with PVC has virtually no protection from fire. Even worse it creates toxic fumes! Plenum however is much safer, but more expensive at that. Most cities require the network installations of ONLY those types of cables. The reason that it's called "plenum" is that the space between the ceiling of a hypothetical office, and it's legitimate concrete ceiling is called the "plenum". A third rating, which isn't very notable sense it isn't standard or as safe as plenum, is the "riser" rating. I just thought that was worth noting.

Finally, let's talk about some big standards. The "Network Industry Standards" created by the IEEE (Institute of Electrical and Electronics Engineers) defines the standards in the implementation of technology. Some history, in February of 1980 it was taken over by the 802 Working Group, which was a company given the job of developing standards. So the IEEE 802 created many cabling standards. However, there are many IEEE committees which create standards for many electronic devices such as printers or even FireWire. Anyways, even more bureaucracy and fragmentation occurred when subcommittees were also created (ex: IEEE 802.3, or 802.5). Of course as you can imagine, many of these committees and subcommittees have been disbanded. To finish, it should be noted that for the Network+ exam, you should definitely know the IEEE 802.3 and 802.11 standards. Thanks for reading, and tschuss!