The distinction can be arbitrary between a computer bus, often closer in space, and larger telecommunications networks.
Many device interfaces or protocols (e.g., SATA, USB, SAS, PCIe) are used both inside many-device boxes, such as a PC, and one-device-boxes, such as a hard drive enclosure.
Accordingly, this page lists both the internal ribbon and external communications cable standards together in one sortable table.
Most of the listed rates are theoretical maximum throughput measures; in practice, the actual effective throughput is almost inevitably lower in proportion to the load from other devices (network/bus contention), physical or temporal distances, and other overhead in data link layer protocols etc.
The maximum goodput (for example, the file transfer rate) may be even lower due to higher layer protocol overhead and data packet retransmissions caused by line noise or interference such as crosstalk, or lost packets in congested intermediate network nodes.
Contention in a wireless or noisy spectrum, where the physical medium is entirely out of the control of those who specify the protocol, requires measures that also use up throughput.
It is extremely common for throughput to be far less than half of theoretical maximum, though the more recent technologies (notably BPL) employ preemptive spectrum analysis to avoid this and so have much more potential to reach actual gigabit rates in practice than prior modems.
Choosing service providers or interfaces based on theoretical maxima is unwise, especially for commercial needs.
A good example is large scale data centers, which should be more concerned with price per port to support the interface, wattage and heat considerations, and total cost of the solution.
Because some protocols such as SCSI and Ethernet now operate many orders of magnitude faster than when originally deployed, scalability of the interface is one major factor, as it prevents costly shifts to technologies that are not backward compatible.
Underscoring this is the fact that these shifts often happen involuntarily or by surprise, especially when a vendor abandons support for a proprietary system.
Where channels use line codes (such as Ethernet, Serial ATA, and PCI Express), quoted rates are for the decoded signal.
802.11 networks in ad hoc mode are still half-duplex, but devices communicate directly rather than through an access point.
While the gross data rate equals 33.3 million 4-bit-transfers per second (or 16.67 MB/s), the fastest transfer, firmware read, results in 15.63 MB/s.
[42] y Uses 128b/130b encoding, meaning that about 1.54% of each transfer is used for error detection instead of carrying data between the hardware components at each end of the interface.
For example, a single link PCIe 6.0 interface has an 64 Gbit/s total transfer rate, yet its usable bandwidth is only 60.5 Gbit/s.
For direct comparison to the values for 64-bit modules shown above, video RAM is compared here in 64-lane lots, corresponding to two chips for those devices with 32-bit widths.