Interframe gap
Encyclopedia
Ethernet
devices must allow a minimum idle period between transmission of Ethernet frame
s known as the interframe gap (IFG), interframe spacing, or interpacket gap (IPG). A brief recovery time between frames allows devices to prepare for reception of the next frame. The minimum interframe gap is 96 bit
times (the time it takes to transmit 96 bits of raw data on the medium), which is 9.6 μ
s for 10 Mbit/s Ethernet, 960 n
s for 100 Mbit/s (fast
) Ethernet, 96 ns for 1 Gbit/s (gigabit
) Ethernet, and 9.6 ns for 10 Gbit/s (10 gigabit
) Ethernet.
Several adapter manufacturers design their adapters with a smaller interframe gap for higher data transfer rates, which can lead to a high rate of collisions. An example is Intel EtherExpress 100B.
IFG Shrinking is allowed on repeaters towards the DTE (Data terminal equipment
) and MII (Media Independent Interface
) into the MAC (Media Access Control
). This is to account for variable network delays, added preamble bits, and clock tolerances.
On reception, some interframe gaps may be smaller due to variable network delays, clock tolerances, and the presence of repeaters.
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
devices must allow a minimum idle period between transmission of Ethernet frame
Ethernet frame
A data packet on an Ethernet link is called an Ethernet frame. A frame begins with Preamble and Start Frame Delimiter. Following which, each Ethernet frame continues with an Ethernet header featuring destination and source MAC addresses. The middle section of the frame is payload data including any...
s known as the interframe gap (IFG), interframe spacing, or interpacket gap (IPG). A brief recovery time between frames allows devices to prepare for reception of the next frame. The minimum interframe gap is 96 bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
times (the time it takes to transmit 96 bits of raw data on the medium), which is 9.6 μ
Microsecond
A microsecond is an SI unit of time equal to one millionth of a second. Its symbol is µs.A microsecond is equal to 1000 nanoseconds or 1/1000 millisecond...
s for 10 Mbit/s Ethernet, 960 n
Nanosecond
A nanosecond is one billionth of a second . One nanosecond is to one second as one second is to 31.7 years.The word nanosecond is formed by the prefix nano and the unit second. Its symbol is ns....
s for 100 Mbit/s (fast
Fast Ethernet
In computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s. Of the fast Ethernet standards 100BASE-TX is by far the most common and is supported by the...
) Ethernet, 96 ns for 1 Gbit/s (gigabit
Gigabit Ethernet
Gigabit Ethernet is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second , as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks where it performed...
) Ethernet, and 9.6 ns for 10 Gbit/s (10 gigabit
10 Gigabit Ethernet
The 10 gigabit Ethernet computer networking standard was first published in 2002. It defines a version of Ethernet with a nominal data rate of 10 Gbit/s , ten times faster than gigabit Ethernet.10 gigabit Ethernet defines only full duplex point to point links which are generally connected by...
) Ethernet.
Several adapter manufacturers design their adapters with a smaller interframe gap for higher data transfer rates, which can lead to a high rate of collisions. An example is Intel EtherExpress 100B.
IFG Shrinking is allowed on repeaters towards the DTE (Data terminal equipment
Data terminal equipment
Data Terminal Equipment is an end instrument that converts user information into signals or reconverts received signals. These can also be called tail circuits. A DTE device communicates with the data circuit-terminating equipment...
) and MII (Media Independent Interface
Media Independent Interface
The Media Independent Interface was originally defined as a standard interface used to connect a Fast Ethernet MAC-block to a PHY chip.The MII design has been extended to support reduced signals and increases speeds...
) into the MAC (Media Access Control
Media Access Control
The media access control data communication protocol sub-layer, also known as the medium access control, is a sublayer of the data link layer specified in the seven-layer OSI model , and in the four-layer TCP/IP model...
). This is to account for variable network delays, added preamble bits, and clock tolerances.
On reception, some interframe gaps may be smaller due to variable network delays, clock tolerances, and the presence of repeaters.
- For 10 Gigabit Ethernet10 Gigabit EthernetThe 10 gigabit Ethernet computer networking standard was first published in 2002. It defines a version of Ethernet with a nominal data rate of 10 Gbit/s , ten times faster than gigabit Ethernet.10 gigabit Ethernet defines only full duplex point to point links which are generally connected by...
received IFG can be reduced to a period of 40 bit times (5 bytes). - For Gigabit EthernetGigabit EthernetGigabit Ethernet is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second , as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks where it performed...
received IFG can be reduced to a period of 64 bit times (8 bytes). - For Fast EthernetFast EthernetIn computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s. Of the fast Ethernet standards 100BASE-TX is by far the most common and is supported by the...
received IFG is not specified. - For EthernetEthernetEthernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
received IFG can be reduced to a period of 47 bit times.