interpacket

Interpacket, often called the Interpacket Gap (IPG) or Inter-Frame Gap (IFG), is the minimum time interval that must elapse between the end of one packet and the start of the next on a shared communications medium, most commonly Ethernet. It serves several purposes, including allowing networks and network interface cards to switch from transmit to receive mode, providing a buffer period for line state stabilization, and, in legacy CSMA/CD networks, aiding collision detection and avoidance.

In Ethernet, the IPG is defined as a fixed number of bit times: 96 bit times. The actual time this represents depends on the link speed. At 10 megabits per second, the IPG is 96 bits / 10 Mbps = 9.6 microseconds. At 100 Mbps, it is 0.96 microseconds, and at 1 gigabit per second, it is 0.096 microseconds. This interval is independent of the size of the frames being transmitted, though it interacts with other timing constraints such as the minimum frame size (64 bytes for Ethernet) and, historically, the slot time used for CSMA/CD operation.

Beyond its role in traditional Ethernet, the concept of interpacket gaps is relevant in traffic analysis and network design. Some measurement tools report interpacket gap or inter-arrival times to characterize burstiness and to assist in traffic shaping, quality of service, or rate-limiting configurations. In switched or full-duplex Ethernet networks, IPG management is largely handled by hardware, and the practical impact is most noticeable in measurement, performance tuning, and ensuring compatibility with legacy timing requirements.