| 摘要 |
A session protection system for an ATM packet switching network enables real-time data to be protected from unauthorised access. The usual rules for transmission/reception ensure ATM cells are delivered in the order transmitted, and with a consistent VP or VP/VC value. ATM defines an adaptation layer for transmitting packets through a VC, whereby adaptation layer endpoints break packets into cells and packet transmission relies on both rules for correct operation. The session protection system disrupts this control and employs at least one pseudo random number generator (PRG1,PRG2), located in a transmitting network element (A) to break at least one of the rules by either delivering cells in a different order or delivering ATM cells with a non-consistent VP or VP/VC value. At least one pseudo random number generator (PRG1,PRG2) at a receiving network element (B) either reassembles cells in the order of transmission, or with a consistent VP or VP/VC value respectively. Exchange keys are used to synchronise the pseudo random generators. |
