In August/September 2006 Telkom started to upgrade their DSL1024 subscribers to 4 Mbps downlink speeds. This was widely welcomed by the broadband community, especially since these were automatic upgrades at no additional cost to subscribers.
Telkom is currently trialing their new 8 Mbps ADSL service, and it is likely that many current DSL 4 Mbps will be upgraded to the higher speeds over the next few months – again free of charge.
This is encouraging news, but some industry players have raised concerns that Telkom is struggling to cope with capacity related to their current ADSL network – something which may be aggravated by an upgrade to 8 Mbps.
ADSL network capacity constraints?
According to one industry player, who asked to remain anonymous, he believes that Telkom has capacity constraints at exchange level – hence old DSLAM cards and the like – which means that many 4 Mbps ADSL subscribers don’t get full speeds.
Another industry expert said that he feels the problem is related to ATM backhaul capacity problems rather than problems at the exchange, forcing Telkom to limit the speed of its highest speed ADSL offerings to avoid congestion.
There has long been rumours that Telkom’s ATM network is running at close to capacity, and that there is often no additional capacity for clients who require more ATM bandwidth.
Telkom however disputes the suggestions that its 4 Mbps ADSL service does not perform at optimal speeds.
“Telkom’s 4Mbps services do perform within the stipulated specifications, however it must be noted that the speed of an end-to-end connection may also be influenced by factors outside Telkom’s network,” Telkom said. “The remote user or data server end and its connection to the Internet and SAIX network play a critical role in the customer’s experience too. “
Telkom explained that Internet connectivity depends on two types of connectivity, namely the backhaul connectivity to the SAIX network and the peering connectivity to other networks locally and internationally. “These are managed independently and are provisioned in order to ensure sufficient capacity,” Telkom said.
Regarding concerns about line sync speeds and backhaul capacity constraints on the ADSL network, Telkom explained that the line sync speed and the backhaul are not technically related and are not coupled.
Telkom added that it does not limit sync speeds and that services are offered at the maximum speed that products allow, restricted only by the condition of the copper line.
“Lower stabilized sync speeds are only applied to lines that cannot run without errors at the maximum speed, e.g. if a “Fastest DSL” service sync at 3.2Mb/s it means that the line condition between the exchange and the customer is not good enough to support 4Mb/s. This line may become unstable and re-sync often. For that reason, at the customer’s request, the line will be placed on a stabilized 3Mb/s sync profile to provide a better service experience to the customer by avoiding frequent re-sync attempts.”
No backhaul constraints
“A congested backhaul will result in varying download speeds based on the source of the content being downloaded. Telkom’s backhaul links are constantly monitored and managed from the utilisation and provisioning perspective,” Telkom said.
“This management of links ensures that the service remains within the official parameters as communicated to ICASA (eg. 20:1 oversell ratio for Telkom’s faster DSL 512kbps service) thereby maintaining great service experience at an affordable price.”
Telkom added that, for the most part, it has adequate backhaul capacity and that their network ordinarily runs without congestion in the backhaul. “Congestion-related upgrading that is constantly being undertaken by Telkom affects currently less than 5% of Telkom’s backhaul network,” Telkom said.
Telkom said that they constantly monitor their network for congestion and endeavor to rectify matters pertaining to congestion as expeditiously as possible. “We consistently seek out different technologies to support high bandwidth requirements. Metro Ethernet, for example, has been deployed to cater for increases in the bandwidth requirement,” Telkom concluded.
Telkom 4 Mbps ADSL << do you get full speed?