Final update on the exchange problems over Christmas
BT Wholesale has released a note on the investigations into the intermittent access problems at a number of BT exchanges over the Christmas period. For those who do not remember the problems, have a look at our news for December 23rd 2002.
The problem would appear to have been down to the setup of the new DSLAMs that where installed at these exchanges. BT Wholesale in conjunction with Fujitsu have determined the problem with the FDX DSLAM installed at these exchanges was downstream buffers were becoming overfilled by data for lines that werent up (i.e. not synced/trained). This downstream behaviour is part of a dynamic buffer allocation scheme that is used to optimise 'burst' traffic conditions.
Fujitsu will now be using a different default configuration on new exchanges, this should ensure that we do not see a repeat of these problems.