The problem is the Akamai node that's hosted by the Internet Solutions in Cape Town:
QUOTE(TENET)
It would seem that at about lunch time Akamai started to do maintenance on their Cape Town Cluster. As a result the vast majority of the traffic normally sourced from this location is now being sourced internationally.
Akamai is one of the world's largest content providers, hosting the likes of Microsoft, Yahoo!, parts of facebook.com, etc. As a result, there's typically a significant amount of traffic between Rhodes' network and the Akamai node in Cape Town (roughly 2Mbps on average). Whilst Akamai work on their Cape Town node, this traffic will compete with other international sites on our congested international link. This will cause a general slow-down of Internet traffic, particularly traffic that's served over the international link. You can see the effects of this on our traffic graphs.
Unfortunately, from Akamai's perspective as a global content provider, turning one node off should now (and does not really) affect their ability to deliver content. It is only because South Africa has differential pricing between national and international bandwidth, and because international bandwidth is scarce here that this affects us so badly. This is a uniquely African problem, and is not something that Akamai are really concerned about. As a result, we don't usually get any notification from Akamai that they're going to be doing this sort of work, nor do we have any idea what they're doing or how long it'll take.