Method for adapting a constant bit rate client signal into the path layer of a telecom signal
A method for rate adapting a constant bit rate (CBR) client signal into a signal stream in a telecom signal communication link includes at a source node encoding into a control block a control block header, and an ordered set block-designator, encoding into a plurality of path overhead data blocks a data block header and a count of data blocks to be encoded in a signal block, encoding into each of a plurality of signal blocks a data block header, the data blocks from the CBR signal equal to the count and pad blocks, assembling the blocks into a path signal frame, appending a set of idle character blocks following the end of the path signal frame to match a link bit rate of a first link segment, and transmitting the path signal frame and idle character blocks into the first link segment at the link bit rate.
1. A method for rate adapting a constant bit rate client signal into a signal stream in a 64B/66B-block telecom signal communication link, the method comprising:
at a source node encoding into a control 64B/66B block an ordered set block-designator;
at the source node encoding into a plurality of path overhead 64B/66B data blocks a count of data blocks to be sent in a next path signal frame;
at the source node encoding a total number of data blocks from the constant bit rate client signal equal to the count encoded in the path overhead 64B/66B data blocks of a previous path signal frame to obtain a plurality of encoded client data signal 64B/66B blocks, and encoding a plurality of 64B/66B pad blocks;
assembling the plurality of path overhead 64B/66B data blocks, the plurality of encoded client data signal 64B/66B blocks, the encoded plurality of 64B/66B pad blocks, and the control 64B/66B block into a path signal frame, the control 64B/66B block occupying a last position in the path signal frame, the path signal frame following the previous path signal frame and preceding the next path signal frame; and
appending a number of idle character 64B/66B blocks at a position following the control 64B/66B block following the end of the path signal frame to match a link bit rate of a first link segment.
2. The method of claim 1 further comprising transmitting the path signal frame and the appended number of idle character 64B/66B blocks from the source node into the signal stream at the first link segment at the link bit rate.
3. The method of claim 1 wherein:
the count of-data blocks to be encoded in the plurality of path overhead 64B/66B blocks is variable; and
the appended number of idle character 64B/66 blocks is fixed.
4. The method of claim 3 wherein the plurality of 64B/66B pad blocks are distributed among the encoded client data signal 64B/66B blocks.
5. The method of claim 1 wherein:
the count of data blocks to be encoded in the plurality of path overhead 64B/66B data blocks is fixed; and
the appended number of idle character 64B/66B blocks is variable.
6. The method of claim 2 , further comprising:
receiving the path signal frame with the appended number of idle character 64B/66B blocks from the first link segment at an intermediate node;
adapting the link bit rate to a bit rate internal to the intermediate node by appending additional idle character 64B/66B blocks to the set of idle character 64B/66B blocks when the link bit rate is slower than a bit rate in the intermediate node and by deleting idle character 64B/66B blocks from the set of idle character 64B/66B blocks when the link rate is faster than the bit rate in the intermediate node to form a modified set of idle character 64B/66B blocks; and
transmitting the path signal frame and the modified set of idle character 64B/66B blocks into the signal stream at a second link segment from the intermediate node at a respective link bit rate.
7. The method of claim 6 , further comprising:
receiving the path signal frame and the modified set of idle character 64B/66B blocks at the respective link bit rate from the second link segment at a sink node;
extracting in the sink node the count of data blocks from the plurality of path overhead 64B/66B data blocks;
extracting from the encoded client data signal 64B/66B blocks in the path signal frame, in the sink node, the data blocks from the constant bit rate client signal;
regenerating from the extracted data blocks the constant bit rate client signal; and
determining in the sink node a bit rate of the constant bit rate client signal from a sink node reference clock, the extracted count of data blocks and the number of idle character 64B/66B blocks in the modified set of idle character 64B/66B blocks; and
adjusting the rate of a constant bit rate client signal clock for transmitting the constant bit rate client signal at the bit rate of the constant bit rate client signal.
8. The method of claim 1 further comprising:
at the source node encoding into the control 64B/66B block a control block sync header;
at the source node encoding into each of the plurality of path overhead 64B/66B data blocks a data block sync header; and
at the source node encoding into each of the plurality of signal 64B/66B blocks a data block sync header.