A network switch allows multiple machines to connect to each other. Like all computer equipment there is a large variety of devices available covering a wide range of prices, features, and reliability.
When buying a switch you will need to determine the speed and the number of ports you need. Ports are the number of network connections or devices you have on the network. This will generally follow this formula:
number of thin clients + number of NAS devices (file servers) + number of LTSP servers + 1 for the みる directory servers + number of network devices = total ports |
Network devices include the router/firewall, managed switches, printer servers, wireless access points, etc.
For example a basic installation with 20 thin clients would need 24 ports:
20 + 1 ✕ NAS + 1 ✕ LTSP server + 1 ✕ みる directory server + 1 ✕ router/firewall = 24 ports
Network switches are usually built with a standard number of ports, e.g. 4, 8, 12, 24, 32, 48, 64. You can have at most 254 devices on a network, beyond that you will need a more advanced network configuration which could vary significantly depending on your requirements.
Network switches are available in different speeds, including the ability to run at different speeds. Speeds are usually in powers of 10 for wire connections, i.e. 10 megabits per second (mb/s), 100 mb/s, 1000 mb/s or 1 gb/s, and 10 gb/s, and vary for wireless, i.e. 8 mb/s, 54 mb/s and 108 mb/s. Technology has improved such that 100 mb/s networks are the same price as 10 mb/s such that the slower speed is not so common. LTSP clients use approximately 300 KB/s so you can guess the number of clients from this table, however be warned speeds can vary drastically depending on usage, this assumes low graphics, no video or audio.
network speed number of clients 8 mb/s (802.11b) 3 10 mb/s 4 54 mb/s (802.11g) 23 100 mb/s 42 1000 mb/s 426
The full network speed is only required for the port that the LTSP server connects too, it is also recommended for the みる directory server to ensure reasonable boot times. Switch manufacturers often sell special devices with only two to four ports at the higher speed, and so a 48 port 10/100 switch with two 100 mb ports can happily sustain 40 users.
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