BT Wholesale delay final part of MTU fix until July 2003
BT Wholesale has decided to delay until 31st July 2003, the final steps in eliminating the fragmentation issues on the Broadband platform. The reason given for the delay is that BT wants to minimize the risk factor associated with other upgrades to the platform. This means upgrade work to implement PPPoE support will go ahead as planned.
BT Wholesale has reminded service providers of the core problem which is "Fragmentation across Colossus, our core IP network was identified as key cause of high CPU utilisation on the home gateway routers of BT Centrals. The high processor load was caused by reassembling of IP packets that had been fragmented. Whilst the processors load is higher than originally planned the BT Central products are still performing to their published throughput specification.". This has been an on-going problem since November 2002, as detailed in BTs original briefing.
It is important that people continue to ensure their MTU value is running at 1458 bytes or lower. The penalty of running at the Windows default of 1500 can be that at peak times you may suffer slower downloads than someone with an optimised MTU. Additionally if enough people do not run with a decent MTU value, all users may actually see slower throughput. An excellent guide explaining what you need to do to check and correct your MTU is available here, or a simpler Windows based application can be downloaded from here