Infrastructure Hardware

CAT6a is a 10-Gigabit Ethernet (10-GbE) over copper proposal to the CAT6 standard. The IEEE published a draft standard (Std 802.3an) in October 2004. The draft calls for 10-Gigabit data transmission over a 4-connector twisted-pair copper cable for a distance of 100 meters on Class F or Class E-augmented copper cabling. Class E cabling requires a line-encoding scheme (PAM 12) and electronics to achieve the 10-Gbps transmission for 100 meters. Current CAT6 cabling systems may support 10-Gigabit Ethernet over limited distances.

The draft extends CAT6 electrical specifications from 250 MHz to 500 MHz. It also proposes a new measurement: Power-Sum Alien Crosstalk to 500 MHz. Alien Crosstalk (ANEXT) is a coupled signal in a disturbed pair arising from a signal in a neighboring cable.
To virtually eliminate the problem of ANEXT, CAT6a F/UTP cable can be used. The F indicates an outer foil shield. This cable is also a good choice when security is an issue because it doesn’t emit signals. In addition, CAT6a F/UTP cable works well in noisy environments with a lot of EMI. Installation is simpler, too, because the cable’s construction makes it easier to pull and more resilient. The cable also has a smaller diameter so you can run more cables in a conduit.

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.

V.35 is the ITU (formerly CCITT) standard termed “Data Transmission at 48 kbps Using 60–108 KHz Group-Band Circuits.“

Basically, V.35 is a high-speed serial interface designed to support both higher data rates and connectivity between DTEs (data-terminal equipment) or DCEs (data-communication equipment) over digital lines.

Recognizable by its blocky, 34-pin connector, V.35 combines the bandwidth of several telephone circuits to provide the high-speed interface between a DTE or DCE and a CSU/DSU (Channel Service Unit/Data Service Unit).

Although it’s commonly used to support speeds ranging anywhere from 48 to 64 kbps, much higher rates are possible. For instance, maximum V.35 cable distances can theoretically range up to 4000 feet (1200 m) at speeds up to 100 kbps. Actual distances will depend on your equipment and cable.

To achieve such high speeds and great distances, V.35 combines both balanced and unbalanced voltage signals on the same interface.