Networking

Getting to know cables, part 1: The 10-Mbps arena

An understanding of legacy technology can often save you hours of frustration. In part one of this two-part cable guide, we'll look at the older, slower 10-Mbps standard of networking cable.


So you are about to redesign your network topology. You know how overwhelming that task can be. You've been in the IT industry for a while, and you think you have all the knowledge you need safely tucked inside your ever-expanding brain. Then it happens: You're putting pen to paper when you realize you don't remember the specifications among the various cable types.

Well, thank goodness for TechProGuild’s network cable guide! With this installment of TechProGuild’s handy guide, you’ll have an explanation of the various cable technologies available in the 10-Mbps arena. Sit back, grab your favorite beverage, and read on, McDuff!

10-Mbps
We start our guide with the slower 10-Mbps cable technology. Within the 10-Mbps framework, you have four possible types:
  • 10Base5—Thick-coax
  • 10Base2—Thin-coax
  • 10Base-T—Twisted-pair
  • 10Base-F—Fiber-optic

The above identifiers are common. The first part of the identifier represents the media speed (the above types are all 10 Mbps). The next part of the identifier, Base, represents the type of signaling (in this case, baseband, which means that the Ethernet signals are the only signals carried on the line). The final section of the identifier represents (roughly) the segment length. The segment length is a critical aspect of cable technologies. For example, if you are dealing with 10Base5, you know that each cable segment can stretch only 500 meters before the segment needs a repeater.

Confused? Let me attempt to explain.

An Ethernet signal can travel only so far before its strength dissipates into a useless form. Repeaters take these signals—before they weaken—and amplify them so they can be sent on yet another segment. Repeaters are less intelligent than bridges, gateways, or routers, and they work on the Physical layer of the Open Systems Interconnection (OSI) reference model.

With each type of Ethernet cabling/technology, repeaters are necessary at different distances. Let's break down each of the above 10-Mbps technologies and apply them to a repeater.

10Base5
This technology (also called ThickNet) uses Attachment Unit Interface (AUI) connectors and RG-8 thick coaxial trunk cable (also known as “frozen orange garden hose”). Throughout the trunk run, the cable will be punctured with taps that have AUI drop cables. The drop cables attach to the desired computer network interface card (NIC). ThickNet can travel 500 meters per segment (before it requires a repeater), and it can have a maximum of 100 drop cables per segment. Each drop cable requires a minimum distance of 2.5 meters before the next drop and has a maximum drop distance (standard office drop) of 50 meters. The drop cable must be terminated with a 50-ohm terminator.

Because of the complex and slow nature of 10Base5, it is rarely used today. It is also a poor solution because a failure anywhere on the trunk will bring down the entire line. This is not a strong solution for any type of LAN technology.

If you are stuck with using ThickNet technology on your network, your primary concern should not be to get perfect measurements (theoretically, it should be, but in practice it's a different story) but to use quality—and properly working—hardware. Common issues with 10Base5 network technologies are bad transceivers or transceivers with the Signal Quality Error (SQE) switch turned on.

The one plus to using ThickNet is that once it's up (and running), it will continue to do so until you tell it otherwise. Although it is slow and unwieldy, 10Base5 technology is very reliable.

Useful installations: Because this technology is rather outdated, it would be best to avoid it in favor of a newer standard.

10Base2
Physically, the biggest difference between 10Base2 (ThinNet) and 10Base5 (ThickNet) is the size of the trunk cable. (10Base2 is much thinner—hence the name ThinNet.) Another difference is that 10Base2 is set up in a daisy chain. The daisy chain is accomplished with T-connectors that attach to the computers’ NIC.

ThinNet uses BNC connectors attached to a thin coaxial cable. The maximum segment length of 10Base2 is 185 meters, and the maximum number of devices per segment is 30.

Useful installations: Although this technology is outdated, it could be deployed as a backbone for a network.

10Base-T
Also called Standard Ethernet, or twisted pair, 10Base-T works on a star topology connecting all computers to a hub. It is best used with Category 5 cable (so it can be upgraded to Fast Ethernet) and can have a maximum of three hubs daisy-chained together.

This is the most widely used of the 10Base technologies because it is simple and cheap to implement. The specifications of Standard Ethernet include the following:
  • It uses RJ45 connectors on unshielded twisted-pair (UTP) cable.
  • The maximum cable length is 100 meters (before a repeater is needed).
  • The maximum number of devices per segment is 1,024 (although performance will become quite poor before that number is ever reached).

Useful installations: This is the current office standard. The 10Base-T standard is best employed within a LAN where cost is a factor—and speed and distance are not.

10Base-F
The fiber equivalent of 10Base-T, 10Base-F uses a higher quality cabling technology, multimode (or single-mode) fiber-optic cable, to transport data. Again, this technology is baseband, so it is transporting only Ethernet signals. The particular technology has two subdivisions that must be addressed: the newer 10Base-FL and 10BaseFOIRL.

Because it is older, the 10BaseFOIRL (Fiber-optic Inter-repeater Link) technology doesn't have quite the capabilities of the newer 10Base-FL. With 10BaseFOIRL, you have the following specs:
  • It’s based on IEEE 802.3.
  • The segment length is 1,000 meters.
  • There are three sizes of duplex multimode fiber: 50-, 62.5-, or 100-micron. Of these three, 62.5-micron is the most common.
  • ST or SMA 905 connectors are used by 10BaseFOIRL.
  • It must be used in a star configuration.
  • AUI connectors have to be connected to fiber transceivers.

The much-improved 10Base-FL technology offers a different set of specs:
  • It’s based on the 10Base-F IEEE 802.3 spec.
  • It’s able to interoperate with FOIRL and is designed to replace the FOIRL specification.
  • The segment length is 2,000 meters (if exclusively using 10Base-FL).
  • The maximum number of devices per segment is two; one is the station and the other is the hub.
  • The maximum number of repeaters that may be used between devices is two.
  • NICs with standard AUI ports must use a fiber-optic transceiver.

The benefits of fiber are many. Outside of the obvious (segment length), there is little radio or magnetic interference. Transmissions are safe from electronic bugging, the cable itself is extremely lightweight, and the cost has come down to a point where it is now an effective solution for many enterprise installations.

Useful installations: 10Base-FL fiber-optic technologies are best implemented in long runs where reliability and security are critical and speed is not.

Conclusion
Although 10-Mbps technology is rather outdated, it stands to reason that many network administrators have to deal with legacy systems that rely on this slower, heavier technology. I hope this little guide has given you an understanding of the technology that helped lay the framework of your network.

Never fear, all ye looking for information on today's standard: We'll be revisiting this guide with a faster 100-Mbps flavor very soon.
The authors and editors have taken care in preparation of the content contained herein but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for any damages. Always have a verified backup before making any changes.

About Jack Wallen

Jack Wallen is an award-winning writer for TechRepublic and Linux.com. He’s an avid promoter of open source and the voice of The Android Expert. For more news about Jack Wallen, visit his website jackwallen.com.

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