Network Wiring
LocalTalk and Ethernet
LocalTalk
The first Mac network was AppleTalk. Using the RS-422 high speed
serial port on the back of two Macs along with the right cable, you
had an instant two computer network. To grow beyond that, whether
by adding a LaserWriter or more Macs, you bought Apple's AppleTalk
adapters and cabling.
Compared with networking in the rest of the computer world,
AppleTalk was very affordable. It was no speed demon, but at
230.4kbps, it was a decent performer. Compared with poky old floppy
disks, it was really nice. (In the real world, you can transfer
about 1 MB of data per minute.)
The folks at Farallon found a way to make this even more
affordable by using plain old phone wire and PhoneNet adapters.
Savvy users could buy a spool of wire, a crimping tool, a pack of
RJ-11 jacks, and enough PhoneNet adapters to build a network very
economically.
Needless to say, PhoneNet quickly replaced Apple's LocalTalk
hardware as the choice of Mac users.
My current employer did this for years, eventually ending up
with about 30 nodes on one very long chain.
But LocalTalk has three significant drawbacks:
- It's slow. At 230.4kbps, it's faster than a modem, but at 1
MB/min, it takes forever to move large files or do backup over the
network.
- It gets congested. All information is broadcast to the entire
network, so a few heavy users can bring it to it's knees. The more
users, the worse it gets.
- It's a daisy chain from one device to the next to the next. If
the wiring goes bad, you end up with two networks that can't talk
with each other
But LocalTalk isn't that slow. ISDN service, which we consider
pretty fast for internet access (well, those of us without cable or
ADSL do), is half the speed of LocalTalk.
Ethernet
What if you could make LocalTalk forty times faster?
You'd have ethernet, a 10Mbps networking protocol that Apple has
been pushing since the Quadra line was released in 1991.
Like LocalTalk, ethernet comes in two basic flavors: coaxial
cables and phone wire. Coaxial uses similar wiring (RG-58) to most
cable TV installations (RG-59) and generally daisy chains from
device to device. As with LocalTalk, a wiring problem turns one
network into two that cannot communicate with each other.
The newer type of ethernet is 10Base-T, which uses heavy duty
phone cable. Unlike LocalTalk and coaxial ethernet, 10Base-T uses
hubs. In a small network, all wires run to a single location; in
larger installations, there may be several hubs in different
locations tied together with ethernet cabling.
LocalTalk and Ethernet
It's a night and day difference between LocalTalk and ethernet.
Both are easy to set up, but 10Base-T is forty times faster. And
that's a huge difference.
The great advantage of 10Base-T is the hub - if one wire goes
bad or gets cut, only one machine is off the network. This makes it
much easier to locate and fix the problem.
Like regular LocalTalk, normal 10Base-T ethernet shares the
entire network between every device. But using a switching hub
(Farallon StarRouter for LocalTalk and a host of different ones for
ethernet), the network is reconfigured on the fly so each port
talks only to one other port at any given instant.
For a busy network, using a switched hub can quickly improve
network throughput by 20% or more.
And for real speed demons, there are faster versions of
ethernet: 100Base-T is ten times faster then plain old ethernet,
and Gigabit ethernet is ten times faster than 100Base-T.
But for home use or most networks with a dozen or less devices,
a regular shared 10Base-T hub is a perfect solution. Shopping
around, you can find 5-port hubs for under US$50 and 8-port hubs
for well under US$100.
Unless you have equipment that's LocalTalk only and can't be
adapted to ethernet, ethernet is the way to go. Hardware is
inexpensive, cabling is inexpensive, most Macs already have
ethernet ports, and it's fast.
Next: Bridging LocalTalk and
Ethernet
Go to Low End Mac
Networking.
