Infrastructure Hardware > Adapters

The news on bandwidth
The need for increased bandwidth never ceases—the more you have, the more you need. Applications keep getting more complex, and files keep getting bulkier. It won’t be long before you need to increase the speed of your network.

Don’t worry. Black Box experts are ready 24 hours a day to answer your questions. When you click on “Talk to a Tech,” you’ll be talking to a trained expert in seconds. If you need help installing a network, or adding an additional drop, contact us.

Because unshielded twisted-pair UTP cable is by far the most common networking cable, let’s take a brief look at where UTP is headed.

The limits of Category 5
Category 5 (CAT5) cabling is good, solid cable for 100-Mbps LANs. The Category 5 standard has been around since 1991, so it’s well established. You’ll find existing Category 5 installations everywhere. What can Category 5 cable do, and what can’t it do?

If you still have a lot of 10-Mbps equipment, CAT5 cabling will serve your needs. It also handles 100-Mbps Fast Ethernet transmissions very well.

But if you’re running up against the performance limits of a 100-Mbps network, you’ll probably want to upgrade at least parts of your system fairly soon to Category 5e (CAT5e) or higher.

Category 5e: the improved Category 5
Category 5e, also known as Enhanced Category 5, or CAT5e, was ratified in 1999. It’s an incremental improvement designed to enable cabling to support full-duplex Fast Ethernet operation and Gigabit Ethernet.

The main differences between CAT5 and CAT5e can be found in the specifications. The performance requirements have been raised slightly in the new standard.

CAT5e has stricter specifications for Power Sum Equal-Level Far-End Crosstalk (PS-ELFEXT), Near-End Crosstalk (NEXT), Attenuation, and Return Loss (RL) than those for CAT5. Like CAT5, CAT5e is a 100-MHz standard, but it has the capacity to handle bandwidth superior to that of CAT5. With these improvements, you can expect problem-free, full-duplex, 4-pair Ethernet transmissions over your CAT5e UTP.

Category 6
The next level in the cabling hierarchy is Category 6 (CAT6) (ANSI/TIA/EIA-568-B.2-1), which was ratified by the TIA/EIA in June 2002. CAT6 provides higher performance than CAT5e and features more stringent specifications for crosstalk and system noise.

The quality of the data transmission depends upon the performance of all the components of the channel. So to transmit according to CAT6 specs, the jacks, patch cables, patch panels, cross-connects, and cabling must all meet CAT6 standards. (The channel includes everything from the wallplate to the wiring closet.) The CAT6 components are tested individually, and they are also tested together for performance. In addition, the standard calls for generic system performance so that CAT6 components from any vendor can be used in the channel.

CAT6 channel transmission requirements should result in a Power-Sum Attenuation-to-Crosstalk Ratio (PS-ACR) that’s greater than or equal to zero at 200 MHz.

In addition, all CAT6 components must be backward compatible with CAT5e, CAT5, and CAT3. If different category components are used with CAT6 components, then the channel will achieve the transmission performance of the lower category. For instance, if CAT6 cable is used with CAT5e jacks, the channel will perform at a CAT5e level.

Industry standards
The advantage of sticking to the industry standards is the knowledge that your cabling will be compatible with standards applications. But the standards are always being improved upon, and it takes time to ratify a new standard. Often, as with CAT6, the final standard may be different from the proposed standard. For the latest information, contact our FREE Tech Support.

Twisted-Pair Cable Specifications Comparison
Frequency — CAT5, CAT5e: 100 MHz;
CAT6: 250 MHz;
CAT7 (Proposed): 600 MHz
Attenuation (min. at 100 MHz) — CAT5, CAT5e: 22 dB;
CAT6: 19.8 dB;
CAT7 (Proposed): 20.8 dB
Characteristic Impedance — All: 100 ohms ± 15%
NEXT (min. at 100 MHz) — CAT5: 32.3 dB;
CAT5e: 35.3 dB;
CAT6: 44.3 dB;
CAT7 (Proposed): 62.1 dB
PS-NEXT (min. at 100 MHz) — CAT5: no specification;
CAT5e: 32.3 dB;
CAT6: 42.3 dB;
CAT7 (Proposed): 59.1 dB
ELFEXT (min. at 100 MHz) — CAT5: no specification;
CAT5e: 23.8 dB;
CAT6: 27.8 dB;
CAT7 (Proposed): not yet specified
PS-ELFEXT (min. at 100 MHz) — CAT5: no specification;
CAT5e: 20.8 dB;
CAT6: 24.8 dB;
CAT7 (Proposed): not yet specified
Return Loss (min. at 100 MHz) — CAT5: 16 dB;
CAT5e: 20.1 dB;
CAT6: 20.1 dB;
CAT7 (Proposed): 14.1 dB
Delay Skew (max. per 100 m) — CAT5: no specification;
CAT5e: 45 ns:
CAT6: 45 ns;
CAT7 (Proposed): 20 ns

Token Ring, which was engineered for mainframe-based applications, is reliable and fault-tolerant, but it’s also very expensive and not well suited for modern Web-based or client/server-based applications. Token Ring has been largely supplanted by Ethernet, which is less expensive to build and operate and can provide far greater bandwidth. Today’s system administrators usually choose to migrate from legacy Token Ring networks to Ethernet when it’s time to upgrade or expand.

Small companies with small networks that require fewer components might find it practical to switch from Token Ring to Ethernet all at once. If your Token Ring network is connected with CAT5 cable, you can even use your already-installed cable for Ethernet. If you’re using the older Token Ring Type 1 or Type 6 cabling, you’ll either have to run new CAT5 cable or use baluns for impedance conversion.

A large company with a large network investment can find that the cost of a full transition is cost-prohibitive. In this case, a practical approach is to make a gradual move to Ethernet as you add and replace components.

A good first step is to always buy peripheral devices, such as printers, in an Ethernet-ready format. They’re far less expensive than the equivalent Token Ring device (if you can find the Token Ring device at all!) and are easy to attach to a Token Ring network with an Ethernet to Token Ring Adapter

A cost-effective server-based migration solution for Novell® IPX based networks is to install either a Token Ring NIC in the Ethernet server or an Ethernet NIC in the Token Ring server. Then change the server’s configuration to enable the internal router program. Although this method is low cost, it does add traffic and overhead to the server, which can decrease overall network performance.

For an easy, standalone hardware solution for connecting a Token Ring to an Ethernet network, use an Ethernet to Token Ring Bridge. Just connect the bridge to your Token Ring MAU and your Ethernet switch. You should also make sure that both networks have the same network identification—in essence, they will become one logical network.

To build a mixed Token Ring and Ethernet WAN, use a router to connect the two networks. The router enables each network to maintain its own identity.