Study of transmission efficiency of IP packets over ATM using LLC/SNAP encapsulation

This paper studies experimentally the efficiency of ATM technology in transporting IP packets. Efficiency of ATM in transporting IP packets has been a subject of considerable interest and a much-researched topic-studies in the past include [R. Caceres, July 28 1991], [M. Hassan et al., 2000]. This paper attempts to specifically study the efficiency, with LLC/SNAP (logical link control/sub network attachment point) encapsulation technique being employed for transporting small sized IP packets over the ATM AAL5 (ATM adaptation layer 5). Since ATM chops a variable length PDU into fixed length cells and pads additional bytes to create the 48-byte cells, the transmission efficiency offered by ATM for small length PDU of 0-48 bytes ranges as low from 15% to 40%. This paper summarizes the efficiency for small length IP datagrams of size 8 bytes to 1500 bytes, which was verified using a test setup. Transmission efficiency can be defined as the ratio of number of useful bytes to the total number of bytes actually transmitted on the link.