2008/11/24 - Slow Responses From Some Sites
The University is currently experiencing very slow responses from certain web sites, particularly https:// sites. The majority of the affected sites appear to be either international, although there are a few national ISPs we're having difficulty reaching as well.

We're not yet sure of what's causing this, other than its beyond our network.
At least part of this problem is being caused by asymmetric routing -- requests are leaving via one route and coming back via a different one. TENET is currently investigating for us, and has already resolved some of the problematic sites.
We've established that the other part of this problem is an incorrect MTU on incoming packets. This was causing packets that were between 1496 and 1500 characters long (1500 characters is the normal maximum) to be retransmitted, and thus appear "slow". This explains why https:// sites were worse affected than http:// sites.

Neotel is currently working on the problem.
The slow responses problem is now limited to sites that we reach via the Johannesburg Internet Exchange.

It is unclear whether the remaining fault is on Neotel's network or TENET's network. Since a fault on the former is both less obtrusive and more likely than the latter, they're focusing on that aspect at the moment.

If the problem is not fixed by Neotel overnight, TENET will perform an emergency reboot of their core router between 5AM and 6AM tomorrow morning. If this happens, it'll cause a temporary (~ 15 minute) total Internet outage.
It appears that the last of this problem (affecting sites hosted at the Internet Solution such as ABSA & Standard Bank) has just been resolved.

TENET has launched an investigation into the matter, and in particular why changes were made during the current change freeze.