Business ISP Andrews & Arnold ( AAISP ) has launched a scathing attack on BT's 21CN broadband back-haul, claiming that the operators network "simply cannot cope with demand at present". The primary problems are with high latency and some packet loss, mostly during the day when there are any high levels of streaming video media.


There have been concerns about latency and loss on BT's network for awhile, which supports and supplies hundreds of communication providers around the UK, although the recent Fifa World Cup and Wimbledon tournaments have once again exasperated and highlighted the situation.


Latency is effectively the time (delay) it takes for internet or network data/packets to travel between various systems and servers; the faster a server responds the lower your latency (response time / ping, usually reported in milliseconds [ms]). Low latency makes VoIP, VPN and online gaming fast and effective. High latency has the opposite effect.

Excessively high latency, which is often a symptom of faulty hardware or network congestion (as in the case above), can also result in some of the data you attempt to transmit failing to reach its destination (i.e. packet loss).


BT have in the recent past claimed that their 21CN network has oodles of capacity, enough to easily cope with the new generation of superfast 40-100Mbps fibre optic based broadband services ( FTTC, FTTH / P ). However it is not uncommon to hear ISP's expressing private frustrations about latency and congestion issues on BT's 21CN infrastructure.

The difficulties AAISP have experienced are often exasperated by the fact that it has become increasingly tedious to report related problems to BT. Several new changes to the operators XML appear designed to force ISPs into taking a potentially expensive and supposedly "optional" Special Fault Investigation (SFI) service. However SFI's are not able to diagnose latency.

We've received some gripes complaining that a number of recent XML changes have stopped ISPs adding notes to a fault, stopped BT staff seeing the text on the fault rejection, stopped BT staff seeing the ISPs initial notes on a fault report and crucially appear to prevent an ISP from rejecting faults without booking an SFI.


Naturally if your problem is with latency or packet loss on the back-haul/BRAS, which is not appropriate for an SFI, then not being able to communicate this properly to BT makes reporting and identifying the difficulties a lot more complicated.

For its part BT continues claim that its 21CN platform does not have any capacity problems and is working with AAISP to resolve the problems. So far AAISP feels that BT's actual progress has been practically none-existent. We attempted to contact BT about this yesterday but at the time of writing had not yet received any reply.