Overview

Security requirements in EPON are based on the fact that EPON serves noncooperative, private users, but has a broadcasting downstream channel, potentially available to any interested party capable of operating an end station in promiscuous mode. In general, to ensure EPON security, network operators must be able to guarantee subscriber privacy, and must be provided mechanisms to control subscriber s access to the infrastructure. In a residential access environment, individual users expect their data to remain private. For the business access application, this requirement is fundamental. The two main problems associated with lack of privacy are subscriber s susceptibility to eavesdropping by neighbors (a subscriber issue) and susceptibility to theft of service (a service provider issue).

In EPON, eavesdropping is possible by operating an ONU in promiscuous mode: being exposed to all downstream traffic, such an ONU can listen to traffic intended to other ONUs. Point-to-point emulation adds logical link IDs (see Chap. 6) that allow an ONU to recognize frames intended for it and to filter out the rest. However, this mechanism does not offer the required security, as an ONU might disable this filtering and monitor all traffic.

The upstream transmission in an EPON is relatively secure. Due to directivity of a passive combiner, the upstream traffic is visible only to the OLT. Although reflections might occur in the passive combiner, sending some small fraction of upstream power downstream again, the downstream transmission is on a different wavelength than...