Ethernet devices must allow a minimum idle period between transmission of Ethernet packets known as the interpacket gap (IPG), interframe spacing, or interframe gap (IFG). A brief recovery time between packets allows devices to prepare for reception of the next packet. The standard minimum interpacket gap is 96 bit times (the time it takes to transmit 96 bits of raw data on the medium), which is 9.6 µs for 10 Mbit/s Ethernet, 0.96 µs for 100 Mbit/s (Fast) Ethernet, 96 ns for 1 Gbit/s (Gigabit) Ethernet, 9.6 ns for 10 Gigabit Ethernet and .96/3.8 ns for 100/40 Gigabit Ethernet, respectively.
Several adapter manufacturers design their adapters with a smaller interpacket gap for higher data transfer rates, which can lead to a high rate of collisions. An example is Intel EtherExpress 100B.
Smaller IPG are possible on repeaters towards the DTE (Data terminal equipment) and MII (Media Independent Interface) into the MAC (Media Access Control), that is when the packet is received by a node. This is to account for variable network delays, added preamble bits, and clock tolerances.
On reception, some interpacket gaps may be smaller due to variable network delays, clock tolerances, and the presence of repeaters.
- For 40/100 Gigabit Ethernet received IFG can be reduced to a period of 8 bit times (1 byte).
- For 10 Gigabit Ethernet received IFG can be reduced to a period of 40 bit times (5 bytes).
- For Gigabit Ethernet received IFG can be reduced to a period of 64 bit times (8 bytes).
- For Fast Ethernet received IFG reduction is not specified. Standard is 96 bit times (12 bytes).
- For Ethernet received IFG can be reduced to a period of 47 bit times.
- "IEEE 802.3-2012 4.4.2 MAC parameters". Retrieved 2013-12-24.
- "Intel EtherExpress 100B - High rate of collisions on 100-megabit networks". Microsoft co. Retrieved 2010-01-16.