  While feasibility and obtaining a solution of a given network coding problem
are well studied, the decoding procedure and complexity have not garnered much
attention. We consider the decoding problem in a network wherein the sources
generate multiple messages and the sink nodes demand some or all of the source
messages. We consider both linear and non-linear network codes over a finite
field and propose to use the sum-product (SP) algorithm over Boolean semiring
for decoding at the sink nodes in order to reduce the computational complexity.
We use traceback to further lower the computational complexity incurred by SP
decoding. We also define and identify a sufficient condition for fast
decodability of a network code at a sink that demands all the source messages.
