Currently, Gigabit Ethernet tends to be a bit pricey, and it probably won't deliver true gigabit performance across your network. I still believe that implementing Gigabit Ethernet is worthwhile in any organisation with growing bandwidth needs. After all, a well-installed Gigabit Ethernet connection will perform at least seven times better than a standard Fast Ethernet connection. The challenge when implementing Gigabit Ethernet is getting the most performance for the least cost. I recommend beginning the rollout by replacing your existing switches with switches that support 10/100/1000-Mbps connections and that support both fiber and copper. Once you've replaced the switches, the next trick is to figure out where to begin implementing gigabit connections. I suggest using Gigabit Ethernet for all connections between switches. Remember that at any given time, a lot of traffic is probably flowing between your switches. Placing gigabit connections between the switches will prevent the switches from becoming a bottleneck. Best of all, most switches aren't PCI-based and therefore can achieve true gigabit speeds. This means that, assuming your cabling is good, the traffic flowing between your switches can actually flow at 1,000 Mbps, regardless of the limits on other gigabit connections on your network. The next thing I'd recommend is installing two gigabit NICs in each server. One of the gigabit NICs should be attached to one of your switches. Since workstations are also connected to the switches (but at lower speeds), this allows traffic to flow between the workstations and the servers. The reason for implementing this architecture is that it prevents a server's network interface from becoming a bottleneck. For example, suppose that a workstation with a 100-Mbps NIC began a network-intensive operation, such as copying a huge file off a server. If the server and the workstation both have 100-Mbps NICs, it would be possible for the workstation to consume most of the server's available bandwidth. Of course, there are situations that would prevent this from happening, such as when traffic is already excessively high or when QoS is in use. But generally speaking, if the workstation consumes most of the server's bandwidth, there's little left for anything else. However, if the workstation has a 100-Mbps NIC and the server has a gigabit NIC, the workstation won't even come close to consuming all of the available bandwidth. I'd recommend using the server's second NIC to connect to a dedicated switch that is linked only to servers (not workstations). Having a dedicated backbone between the servers makes it possible for server-related traffic, such as that generated by replication and other network functions, to flow through a dedicated network without placing any traffic on the main network. I'd also suggest implementing specific gigabit connections with fiber-optic cable. Use fiber for any connection to a switch or server, and for any gigabit connection that requires a cable run exceeding 100 meters or that flows through an area in which radio interference, crosstalk, or attenuation might be a problem. You should run your workstations at 100 Mbps for reasons that I explained earlier. As Gigabit Ethernet NICs become cheaper, you may later want to upgrade your desktop computers to gigabit speeds. If you do, however, I strongly advise that you run copper cable to the desktops. I've seen far too many cases of cable abuse over the years to recommend running a fiber-optic cable to someone's desk. Fiber-optic cable is too delicate to survive the abuse that users can subject a cable to. Pump up the volume
Although relatively few people are using Gigabit Ethernet compared to other forms of Ethernet, it's quickly becoming more affordable, and eventually, it will be as widely used as Fast Ethernet is now. Planning for Gigabit Ethernet today will save you money and effort when you eventually make the switch. Before you know it, you'll be running your network at gigabit speeds and wondering how it ever worked when it was slower.
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