What is cells in frames (CIF)?
Cells in Frames (CIF) is an ATM (Asynchronous Transfer Mode) protocol that simplifies the transmission of Ethernet data packets. CIF enables the implementation of ATM using existing Ethernet devices such as network interface cards and offers advantages such as quality of service without additional hardware costs.
CIF is an ATM protocol with on-line packets and variable length trunks. The CIF Alliance defines protocols that enable the embedding of ATM headers in frame-based legacy protocols for up to 31 virtual packet switching cells. A key CIF function is an explicit rate flow control.
CIF uses ATM between workstations without changing the legacy NIC cards as it uses 'Shim' software for processing. Variable length packets add less overhead and eliminate the need for new NICs and segmentation / reassembly hardware.
CIF's fixed cell size makes it easy to:
- 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 to mix data, video and voice without delaying line degradation on the same line
- QoS-based traffic routing over network trunks for load balancing and to ensure traffic routing on paths that can support QoS and bandwidth
- Low-delay flow control for high-speed switched networks