VPN operationwhich

The PDIS is dedicated to the candidate NSP architecture to provide a flexibleinterface for application programming and operation description. Furthermore, thePDIS facilitates the task management and resource allocation carried out by theCD. Descriptors generated by the C*Core 310 describe the required operations aswell as their corresponding input and output data packet information; therefore,each descriptor represents one specific network workload task. Figure 7 illustratesthe overview of a system descriptor format which consists of 13 pointer fields. ThePDIS provides considerable programmability such that the system descriptorshown in this figure can describe not only simple cryptographic algorithmoperations, but also complex protocol operations. According to requesting tasks,system descriptors vary in the number of fields and lengths depending on howmany different cipher algorithms are to be performed and the amount of pendingcontext blocks. The simplest system descriptor is just one cryptographic operationwhich may be a 3DES encryption consisting of just 8 pointer fields, while the mostcomplex system descriptor may be the one illustrated in Figure 7, where a IPSec3DES-HMAC-SHA-1-96 ESP mode is described. Meanwhile, the figure shows thedescriptor interpretation procedure in which a complex IPSec descriptor isdisassembled into one simple descriptor for 3DES and one simple descriptor forHMAC. The figure also illustrates how the 3DES descriptor is eventuallyfragmented into one configuration descriptor and its related cluster of dat