This is a list of device bandwidths: the net bit rate (or, more informally, digital bandwidth) of some computer devices employing methods of data transport is quantified in units of kilobits per second (kbit/s), megabits per second (Mbit/s), or gigabits per second (Gbit/s) as appropriate. They are grouped by similar functionality, and then listed in order from lowest bandwidth to highest.
In addition, a common scale is used in order to better convey the magnitude of change to a non-technical person (for example: a 1.2 kbit/s telephone modem versus a 10,000 kbit/s DSL modem). Whether to use bit/s or byte/s (B/s) is often a matter of convention. The most commonly cited unit (bit/s or byte/s) is bolded. In general, parallel interfaces are quoted in byte/s (B/s), serial in bit/s. On devices like modems, bytes may be more than 8 bits long because they may be individually padded out with additional start and stop bits; the figures below will reflect this. Where channels use line codes, such as Ethernet, Serial ATA and PCI Express, quoted speeds are for the decoded signal.
Many of these figures are theoretical maxima, and various real-world considerations will generally keep the actual effective throughput much lower. The actual throughput achievable on Ethernet networks, for example (especially when heavily loaded or when running over substandard media), is debatable. The figures are also simplex speeds, which may conflict with the duplex speeds vendors sometimes use in promotional materials.
Note that the values given are maximum values, and actual values may be slower under certain conditions (for example, noisy phone lines). [2] Where two values are listed, the first value is the downstream rate and the second value is the upstream rate.
Note that the values given are maximum values, and actual values may be slower under certain conditions (for example, noise). Where two values are listed, the first value is the downstream rate and the second value is the upstream rate.
Note that the values given are maximum values, and actual values may be slower under certain conditions (for example, noise). Where two values are listed, the first value is the downstream rate and the second value is the upstream rate.
Note: Actual data throughput is much less than bandwidth of the data transmitted due to overhead and other factors, so do not mistake its speed as actual data transfer rate. "Typically one can expect about ⅓–⅔ of the actual speed based on several factors such as traffic. Also, if there are problems in your physical layer causing retransmissions, your throughput will suffer as well." [15]
Note: 802.11 networks are half-duplex; all stations share the medium. In access point mode, all traffic has to pass through the AP (Access Point). Two stations on the same AP which are communicating with each other will have all traffic pass the medium twice: once sent by the sender to the AP, then from AP to receiver, thus approximately halving the effective bandwidth.
NOTE: Dual channel bandwidths are theoretical maximums and do not always reflect real world performance. In many cases, performance may be closer to single channel operation (half the bandwidth).
^ TTY uses a Baudot code, not ASCII. This uses 5 bits per character instead of 8, plus one start and 1.5 stop bits (7.5 total bits per character sent).
^ abcdefghijk 300 baud modems operating at 30 characters per second, were often described as "reading speed" since the characters scrolled across the screen at the same rate as most people can read. All modems are assumed to be in serial operation with 1 start bit, 8 data bits, no parity, and 1 stop bit (2 stop bits for 110-baud modems). Therefore, a total of 10 bits (11 bits for 110-baud modems) are needed to transmit each 8-bit byte. The "bytes" column reflects the net data transfer rate after the protocol overhead has been removed.
^ ab56K modems: V.90 and V.92 capacity can only be achieved when the upstream (service provider) end of the connection is digital. In addition, certain telecommunications administrations limit the signal strength the modem can transmit onto the telecommunications circuit, which in turn limits the actual maximum data rate to less than the theoretical maximum. In the USA, this limited the possible downstream maximum to 53.3 kbit/s.
^ Note that effective aggregate bandwidth for an ISDN installation is typically higher than the rates shown for a single channel due to the use of multiple channels. A basic rate interface (BRI) provides 2 "B" channels and one "D" channel. Each B channel provides 64 kbit/s bandwidth and the 'D' channel carries signalling (call setup) information. B channels can be bonded to provide a 128 kbit/s data rate. Primary rate interfaces (PRI) vary depending on whether the region uses E1 (Europe, world) or T1 (North America) bearers. In E1 regions, the PRI carries 30 B-channels and 1 D-channel; in T1 regions the PRI carries 23 B-channels and 1 D-channel. The D-channel has different bandwidth on the two interfaces.
^ ADSL connections will vary in throughput from 64 kbit/s to several Mbit/s depending on configuration. Most are commonly below 3 Mbit/s. Some ADSL and SDSL connections have a higher bandwidth than T1 but their bandwidth is not guaranteed, and will drop when the system gets overloaded, whereas the T1 type connections are usually guaranteed and have no contention ratios.
^ abDOCSIS 1.0 includes technology which first became available around 1995-1996, and has since become very widely deployed. DOCSIS 1.1 introduces some security improvements and Quality-of-Service (QoS).
^ abDOCSIS 2.0 specifications provide increased upstream throughput for symmetric services.
^ ADSL connections will vary in throughput from 64 kbit/s to several Mbit/s depending on configuration. Most are commonly below 2 Mbit/s. Some ADSL and SDSL connections have a higher bandwidth than T1 but their speed is not guaranteed, and will drop when the system gets overloaded, whereas the T1 type connections are usually guaranteed and have no contention ratios.
^ Satellite internet may have a high bandwidth but also has a high latency due to the distance between the modem, satellite and hub. One-way satellite connections exist where all the downstream traffic is handled by satellite and the upstream traffic by land-based connections such as 56K modems and ISDN.
^Dave Haynie, designer of the Zorro III bus, claims in this posting that the theoretical max of the Zorro III bus can be derived by the timing information given in ‘’chapter 5’’ of the Zorro III technical specification.
^ Dave Haynie, designer of the Zorro III bus, claims in this posting that Zorro III is an asynchronous bus and with that does not have a classical MHz rating. A maximum theoretical MHz value may be derived by examining timing constraints detailed in the Zorro III technical specification, which should yield about 37.5 MHz. No existing implementation performs to this level.
^ Dave Haynie, designer of the Zorro III bus, claims in this posting that Zorro III has a max burst rate of 150 MB/s.
^ abc PCIe 2.0 effectively doubles the bus standard's bandwidth from 2.5 Gbit/s to 5 Gbit/s
^ abcd Fibre Channel 1GFC, 2GFC, 4GFC use an 8B/10B encoding scheme. Fibre Channel 10GFC, which uses a 64B/66B encoding scheme, is not compatible with 1GFC, 2GFC and 4GFC, and is used only to interconnect switches.