Cisco Adsl ATU-C Dmt Configuration Bit Swap Enabled

1.3.6.1.4.1.9.9.130.1.14.1.7

This object specifies whether the ATU-C performs bitswapping. Bitswapping attempts to maintain an acceptable margin for each bin; equalizing the margin across all bins through bit reallocation, thereby maximizing error performance. The ATU-C performs bitswapping by monitoring the margin measured for each bin by the transmitter: 1) If a bin's margin falls below 'target' and the difference, between the margin and 'target' exceeds 'thresh(f)', then the ATU-C marks the bin as a 'from' bin. 2) If a bin's margin exceeds 'target' and the difference between the margin and 'target' exceeds 'thresh(t)', then the ATU-C marks the bin as a 'to' bin. Where: 'target' = adslAtucConfTargetSnrMgn 'thresh(f)' = cAdslAtucDmtConfBitSwapFrom 'thresh(t)' = cAdslAtucDmtConfBitSwapTo The ATU-C attempts to equalize the margin across the bins by swapping bits out of bins marked 'from' into bins marked 'to'. When the ATU-C swaps a bit out of bin, it decreases its b(i). Thus, the bins constellation is smaller, which increases its margin. When the ATU-C swaps a bit into a bin, it increases its b(i). Thus, the bins constellation is larger, which decreases its margin. In addition, the ATU-R may optionally implement its own monitoring capability. The ATU-R uses this information to request the ATU-C to perform bitswapping. When this object is 'true', the ATU-C must be prepared to accept and properly handle bitswap requests from the ATU-R. While bitswapping has its obvious advantages, bitswapping can have undesirable side effects. It can introduce errors on lines prone to impulse noise. In this case, it may be desirable to disable bitswapping.