Cells In Frames (CIF)

CIF is an ATM protocol with online packets and trunks of variable lengths. The CIF Alliance specifies protocols that permit the embedding of ATM headers in frame-based legacy protocols for up to 31 virtual packet circuit cells. A key CIF feature is explicit rate flow control.

CIF uses ATM between workstations without changing legacy NIC cards, as "Shim" software is used for processing. Variable length packets create lower overhead and eliminate the need for new NICs and segmentation/reassembly hardware.

CIF's fixed cell size facilitates the following:

• High-speed hardware switching
• Small cell size for minimized delays
• Virtual circuit switching for fast switching speeds
• Call-based QoS for call-based flow control
• QoS signaling for mixing data, video and voice without trunk degradation delay on the same wire
• QoS-based traffic routing over network trunks for load balancing and to ensure traffic routing on paths capable of supporting QoS and bandwidth
• Low delay flow control for high-speed switched networks