Packet coalescing is the grouping of packets as a way of limiting the number of receive interrupts and, as a result, lowering the amount of processing required.
In network adapters using Network Driver Interface Specification (NDIS) versions 6.30 and later, packet coalescing is used to group both random and multicast traffic for efficiency.
Packets matching receive filter parameters are cached and released together when any of the following occurs:
- the cache is filled
- an expiration timer is reached
- a packet is received for a different machine and is outside the coalescing filter
- the device reaches its minimum low water mark
- an interrupt event message is received, such as a send completion.
Data sent destined for computers A and B on a network where C also resides will be grouped together so that they are consistently passed along to A and B without checking each packet or forwarding all requests to all computers. That process prevents C from being needlessly hit with unsolicited traffic that it would have to filter for its own requests.