3. Do I Need it?

Most of the early sales literature for gigabit Ethernet contained pitches focused on the "enterprise" market, and usually aimed at the data center manager. Since gigabit Ethernet provides a 10 times larger "pipe" for data flow than 100Base-T, the natural first applications were at the points of highest bandwidth need. Server-to-server, switch-to-switch, and "backbone" applications were all named as candidates for gigabit Ethernet, and there are white papers and case studies a' plenty to show that gigabit Ethernet is a good investment in these cases.

As gigabit gear prices have followed their natural downward march, vendor pitches have widened to include gigabit deployment to desktop machines of "power users" and workgroups with "bandwidth intensive applications".

Since most small networks' data needs are much more modest, it's fair to ask whether a small network would ever need the capacity that a 1000Base-T network provides. Let's look at some of the applications that are commonly used in a small network and see if they need what gigabit Ethernet can provide:

Gaming
Since most networked games are designed for over-the-Internet play, they're pretty savvy about the amount of data they send across the network. The games rely on local processing power for the heavy lifting and send only what they have to across the network, so that they are playable under the wide range of network conditions encountered on the Internet.
Although in gaming, faster is always supposed to be better, gigabit Ethernet won't provide any advantage in networked frag-a-thons. Response time is the important factor for networked gaming, but anything much below 10ms doesn't provide any advantage, and you'll get that from even a 10Base-T network.So, again, gigabit Ethernet's extra capacity will just be wasted for this application

Streaming audio / video / Netmeeting, etc.
The most commonly used streaming video format today is MPEG-2, which requires between 2-6Mbps for "normal" video and 12-20Mbps for broadcast HDTV. There are also high-quality, professional-level, non-broadcast HDTV applications that can push the required bandwidth up to 40Mbps, but it's unlikely that most home and small office networks would need to run at that speed.
The good news, however, is that the bandwidth limitations of the Internet and desire to use wireless networks as a primary streaming video delivery system in the home have pushed the encoding wizards to provide better quality at lower bandwidths. The main result of their efforts is MPEG-4, which is more scalable and provides better quality than MPEG-2 at bandwidths from 64 kbps-4Mbps.
The net result is that unless you're a video production house, or have the need to provide more than four or so simultaneous HDTV streams, your existing 100Base-T LAN will be just fine for the forseeable future.

TIP: See this article for a good description of the bandwidth requirements of the popular MPEG standards.

Moving large files across the network

This requirement is more likely to be encountered in a small-office situation, especially in graphic-design houses, architectural firms, and other businesses that routinely deal with file sizes in the tens to 100+ MegaBytes. Although a quick cut at the math would have you think that a 100 MegaByte file would take only 8 seconds to move across a 100Base-T network [ (100 MByte X 8 bits/Byte) / 100Mbits/sec ], in reality, many factors conspire to make the actual transfer time much longer. Some of the factors that come into play are OS used, applications you're running, amount of memory in your machines, and their processor speed and age. (The age is an indicator of motherboard bus rates.)

One of the factors is also the speed of the networking hardware, and switching to gigabit hardware can remove one of the potential bottlenecks and speed up large file transfers. But as many who have tried will attest, getting higher than 50Mbps performance out of even a 100Base-T LAN is difficult to do, let alone more than 100Mbps on a gigabit LAN!

Network backup

This can be thought of as a variant of the "large files" case. If your LAN is set up to backup all its machines to one system that acts as a fileserver, a gigabit LAN might help speed the process. However, this is another case in which widening the "pipe" to the backup server may have no effect if the server (and especially the backup medium) can't keep up with the incoming flood of data.

If this is your application, you'll need a speedy server with plenty of memory, and be backing up to a fast hard drive, not tape or CDROM, before you should be thinking of upgrading your network components to gigabit stuff.

Server based applications
Another scenario more likely to be encountered in a small business vs. a home LAN is one in which a lot of data frequently moves between a client and server due to a server-based application. But again, you need to analyze the amount of network data to see whether "a lot" would be enough to see an improvement from a switch to gigabit speeds.

Truthfully, I think that most home networkers would be hard-pressed to justify spending the money for gigabit equipment. Some small business might find that moving to a gigabit LAN could help them, but I'd recommend an analysis of their present network's data flows before jumping in.

But let's say that you don't want to rule out the possibility of an upgrade in a year or two, is there anything that you need to do now to prepare? The next section will examine what you need to do for what is frequently the most expensive, and hardest to change part of your network - the cabling.