- By J.B. Miles
- Nov 09, 1998
Build yourself an Ethernet or Fast Ethernet LAN
Most network managers are familiar with the early warning signs of network glut:
Graphics applications bring LANs to a crawl. Ad hoc database searches take eons to
complete. Print jobs stay queued up for hours. Data output from server farms is sluggish
Slow networks threaten the viability of mission-critical operations and may even
threaten the job security of staff network professionals.
And users at hot spots everywhere in the organization clamor for more speed.
But take heart. You can migrate from slow 10-Mbps Ethernet networks to speedier
100-Mbps Fast Ethernet networks without breaking your departmental budget or tossing out
legacy network gear.
Begin the process by popping a 10/100 Fast Ethernet network interface card into your
network workstations and servers, but your network hubs, switches and routers will also
require some upgrading to take advantage of Fast Ethernets full 100-Mbps bandwidth.
Fast Ethernet is included with a limited number of other high-speed networking
technologiesasynchronous transfer mode, the Fiber Distributed Data Interface
100VG-AnyLAN and Gigabit Ethernet. All offer features and benefits that can meet your
speed and connectivity needs.
But all signs indicate that Fast Ethernet is making its way onto more networks than its
competitors and is likely to continue doing so for the foreseeable future.
Sales of Fast Ethernet hubs, switches and other network gear are outpacing those for
the others by a wide margin.
As for NICs, research from the Cahners In-Stat Group of Scottsdale, Ariz., shows that
the growing worldwide market for NICs is driven largely by the continuing migration to
Fast Ethernet. Last spring, for the first time, Fast Ethernet NICs made up 50
percent or more of both units shipped and revenue for the overall NIC market, said
Mike Wolf, an industry analyst for the group.
The success of the Fast Ethernet segment came largely at the expense of Ethernet
NICs, which saw their percentage of the overall market slide to 34 percent in unit terms
and 17 percent of revenues, he said.
Fast Ethernet has a full service bank of features and benefits less readily available
from other technologies, particularly for moving from 10-Mbps standard Ethernet
technology. 100VG-AnyLAN, originally developed by Hewlett-Packard Co., uses a wiring
scheme different from Ethernet and Fast Ethernet. It uses a token-passing architecture.
Although it offers high-speed and a noncontention-based design, it is at the same time an
atypical network architecture.
FDDI also offers 100-Mbps throughput, but usually uses fiber-optic media exclusively
and is best suited for long-distance WAN backbones.
Because it requires different operational standards than do the Ethernet/Fast Ethernet
networks found in most government installations, support for ATM has been sagging. Its
25-Mbps speed to the desktop PC is far less than the 100-Mbps throughput speed of Fast
Although ATM offers speeds of 155-Mbps and higher over fiber-optic backbone cables, it
isnt winning the battle for high-end network users.
Gigabit Ethernet, which offers 1,000 times the speed of Ethernet and 10 times the speed
of Fast Ethernet, is coming on fast but has far from a clear route. Speed bumps such as
standards issues and transmission of rapid data packets over fiber-optic media, are
holding it back.
Because it is rooted in the same Ethernet standards with which most network designers
are familiar, Fast Ethernet offers the best upward migration path. Except for being 10
times faster than Ethernet, Fast Ethernet is fundamentally identical to it.
Fast Ethernet uses the existing 802.3 Media Access Control (MAC) layer interface as
Ethernet. Packet length, error-control and techniques for handling management information
are essentially the same for both.
What is different is the speed at which the MAC layer transfers the packets of
information100 Mbps instead of 10 Mbps.
Fast Ethernet also uses the same star network topology as Ethernet does. Star topology,
unlike the bus topology used by some other networking schemes, provides overall network
reliability in case of a failure anywhere on the network.
Because all network nodes under this scheme are linked to a central hub or wiring
closet, the failure of one or two nodes wont bring the entire system down.
In addition, Fast Ethernet uses most of the same basic and simple wiring schemes as
The 10Base-T Ethernet standard uses Category 3 and 4 unshielded twisted-pair cabling.
UTP cable, which is similar to telephone cabling and is relatively cheap, is in place
at most government and commercial sites.
The 100Base-TX Fast Ethernet standard supports use of Category 5 UTP, which is more
expensive than Category 3 or 4 UTP but offers support for full 100-Mbps throughput on a
single pair of wires.
The 100Base-T4 Fast Ethernet standard can use Category 3 and 4 wiring but at the
expense of adding another two pairs of wires. At this level, standard RJ-45 telephone
connectors can also be used for both the 10Base-T Ethernet and 100Base-TX/T4 or a mixture
of the two speeds.
If you need fiber to unclog your network hubs and routers, the 100Base-FX Fast Ethernet
standard lets you use fiber-optic cabling for specialized applications where high speed is
a requirement and electronic emissions or other radio interference is a concern. SC
connectors are used where multimode fiber cables are used; ST connectors are used with
single-mode fiber cables.
Legacy Ethernet gear, including installed UTP wiring, network servers and even
unmanaged 10Base-T Ethernet hubs, need not be scrapped when you move up to Fast Ethernet.
With the listed 10/100 Fast Ethernet NICs, you can upgrade PCs and workstations to
handle full 100-Mbps service as the networks hubs and switches are changed over.
Fast Ethernet also supports the same network management systems and operating systems as
Best of all, network managers familiar with 10Base-T systems dont undergo much of
a learning curve getting up to speed with Fast Ethernet.
Fast Ethernet technology wins broader support from leading network and systems
manufacturers than all the other high-speed technologies combined. Among Fast Ethernet NIC
vendors, 3Com Corp. commands about 50 percent of the market and Intel Corp. captures about
24 percent. The remaining 26 percent is divided among the other NIC makers listed in the
The perfect NIC may not exist, but youll get the closest thing to one by
following this checklist of features:
Most common today is the PCI bus, used in Pentium and Pentium II systems, and this is
reflected in the predominance of PCI-compliant NICs in this Buyers Guide. A few are
compatible with the older ISA and EISA buses used in Intel 386 and 486 systems, and a few
others are designed for the SBus buses used in Sun Microsystems Computer Co.s Sparc
workstations or Apple Computer Inc.s Macintosh computers with NuBus. External PC
Card or CardBus NICs connect to notebook computers via a Type II or Type III PC Card slot.
100Base-FX NICs are compatible with SC or ST fiber-optic connectors. The Media
Independent Interface is an advanced Fast Ethernet interface that allows connections
between FX (fiber-optic) and TX (copper UTP) NICs.
Gigabit Ethernet offers a tenfold boost over Fast Ethernet speeds of 100 Mbps. When
its perfected, it will be an ideal counterpart to Fast Ethernet, especially as a
high-speed backbone technology for far-flung offices.
It should come as no surprise that analysts predict that by 2000 the market for gigabit
devices will exceed $1.5 billion.
But first there are a few speed bumps to negotiate.
Current gigabit implementations send beams of light across multimode fiber cables at
different speeds, which causes various beams containing data packets to arrive at their
destinations at different times.
This, in turn, requires various means of error-checking, which can drastically slow
The goal of the Institute of Electrical and Electronics Engineers is to synchronize the
signaling process so that data arrives at its destination faster and then establish a
standard that governs compliance with Gigabit Ethernet.
Only a handful of Gigabit network interface cards currently exist. 3Com Corp.s
Gigabit Ethernet Server NIC, priced at $1,695, is a 64- or 32-bit card designed to relieve
network congestion by bringing gigabit power to servers with a PCI bus.
Sun Microsystems Inc.s $2,095 to $2,295 Gigabit Ethernet adapters are designed
for the same purpose and can match with PCI-based servers or Suns own Sparc servers
To assuage buyers fears about the standards question, 3Com guarantees
compatibility of its Gigabit Ethernet products with all future standards.
Meanwhile, companies such as Bay Networks Inc., Cabletron Systems Inc. of Rochester,
N.H., Cisco Systems Inc. of San Jose, Calif., and Lucent Technologies Inc. of Murray Hill,
N.J., along with startups such as Foundry Networks Inc. of Sunnyvale, Calif., are keeping
their IEEE memberships in good stead and preparing to join the upcoming Gigabit Ethernet
J.B. Miles writes about communications and computers from Carlsbad, Calif.