An encoder encodes each of a plurality of data fragments into an encoded packet comprising a plurality of codewords, each codeword comprising a set of data bytes from the data fragment and at least one error-correction byte derived from the set of data bytes. A plurality of cross-interleavers each receive as input one of the plurality of codewords of the encoded packet, after which a concatenator concatenates a plurality of interleaved codewords output by the plurality of cross-interleavers into an interleaved packet to be sent over a network.