The main objective of CIF is to get ATM to the desktop, but to use existing LAN techology to do so (Ethernet/Token-Ring). A main objective is to work with current NIC cards. This is accomplished by tunneling through the LAN, wherein many cells may be collected and packaged into a LAN frame format. And adding software to the desktop to do the CIF ATM-LAN formatting. The ATM switch/concentrator would also do this formatting.
A main thrust is to use the ABR service class. The desktop would execute, in software, the endsystem behavior as specified in TM 4.0. The amount (lines) of code are very few, but the potential execution load is of concern. The code needs to execute the algorithm each tine it receives an RM cell. CIF proposes to significantly reduce the number of RM cells that need to be processed (to once per frame), by optionally operating the switch/concentrator in Explicit-rate and Virtual-Source--Virtual-Destination (VSVD) modes, as provided for by TM 4.0.
Considering that, a CIF-ABR Concentrator (CIF Workgroup switch or what have you)might typically:
A technical article on the Cells-In-Frames (CIF) proposal was published in the IEEE Network magazine (July/August 1996, p9). The article describes the CIF architectural framework for supporting ATM services within standard LAN frames. That is, support for ATM AAL1 and AAL5 services over Ethernet. The article discusses the three proposals for AAL5 services within Ethernet frames. The promise of CIF is to extend most of the QoS benefits of native ATM to legacy Ethernet or Token Ring-attached workstations. Additionally, since CIF is just another way of transporting ATM cells, a client workstation supporting CIF can make use of any ATM LAN techniques and protocols.
Additional Info
Cells in Frames, article by Dr. Lawrence G. Roberts, March 1997
Specifications basis by Dr. Lawrence G. Roberts, August 1996
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