Patent ID: 7359316

Claim:
An apparatus comprising: a pointer processing section for processing a pointer contained in a transmission frame; and a frame identification section for identifying a frame composition of said transmission frame based on pointer processing result of said pointer processing section and for providing such identification result to said pointer processing section, wherein said pointer processing section comprises: a pointer detection section for detecting an NDF-bit, an SS-bit and a pointer value contained in a pointer byte of said transmission frame; and an invalid pointer detection section for detecting that sa id pointer byte is an invalid byte, based on respective detection results in said pointer section; in which said invalid pointer detection section is composed to change over a detection condition of a valid pointer byte according to a reception state and a frame composition of said transmission frame, and to detect as said invalid pointer byte such pointer byte not satisfying said detection condition, said apparatus further comprising a protection section for outputting an LOP state indication when said invalid pointer byte is detected for given number of times consecutively in said invalid pointer detection.