2010/04/25-28 - Slow International Internet Access
Rhodes is currently experiencing slow access to international sites (including .za sites hosted overseas). This problem affects most universities in South Africa, as well as a number of other organisations.

The reason for the slowness is that at present our traffic is being carried by an alternative, lower capacity circuit rather than the SEACOM cable that normally provides us with international Internet access. This circuit has about 3% of the capacity of our regular circuit, and is likely to be somewhat congested.

At the moment scheduled emergency maintenance is being carried out on the SEA-ME-WE-4 fibre optic cable that links SEACOM to Europe. (This is the maintenance that was first announced a week ago.) The maintenance work, which is taking place in the Mediterranean sea, is scheduled to take between six hours and three days, weather depending. We're informed that weather conditions in the Mediterranean are currently delaying the repair work. Once repair work is complete, normal service will be restored.

All Rhodes users are asked to limit their use of non-essential international sites (particularly where this involves significant downloads, etc) until normal connectivity is restored. Depending on the duration of this maintenance work, it may become necessary for us to impose temporary restrictions on access during the course of tomorrow (Monday).
The route changes associated with the above maintenance are affecting Rhodes' IPv6 routing. International IPv6 is currently not working. We've reported the problem to TENET's service desk.
Apparently IPv6 traffic isn't carried over the backup link, and so this won't be restored until maintenance is complete.
We've just been informed that the tentative estimate for completion of the repair work is 27th April.
Since early this morning our traffic has been routed Eastwards, through Mumbai (India) and onwards to Asia. (We normally route North-West, up the coast and straight into to Europe). Taking the long way around the world significantly increases the distance between us and Europe and the Americas and greatly increases the latency we experience. This will add to the perception of "slowness", particularly for sites hosted in Europe.
There are reports in the media suggesting that the maintenance work on SEA-ME-WE-4 may take until 30 April. We haven't yet had any confirmation of this from our service providers. As things currently stand, we're still being routed to International sites via the temporary, congested Eastwards route.

If the maintenance work does persist until the 30th, it is likely that we'll temporarily remove or reduce the demand-side management constraints and/or temporarily lower quotas. (This may become necessary to reduce the congestion on the alternative circuit and allow essential network services to continue.) Any changes to the quota system in this regard will be posted to this thread, so you're encouraged to read it regularly and make sure you're aware of the current status.
The latest update we have available indicates that repair work on SMW4 will be completed on 28th April at 22:00 UTC.
A few minutes ago, our international routing started looping. Users will likely experience this outage as an ERR_DNS_FAIL or ERR_CONNECT_FAIL error when trying to access international websites. When accessing secure (https://) web sites, your browser may report that the connection has timed out or the site is unreachable.

The problem has been reported to TENET's service desk.
The international routing loop, which was due to the SEACOM link flapping as work on SMW4 progressed, has been resolved. However, there is now a separate, unrelated outage which occurred about ten minutes after this problem was fixed.
As of early this morning, we're still routing Eastwards over the alternative route. It isn't clear yet whether this is because SEACOM haven't yet finished maintenance, or whether our routing simply hasn't updated.
We've received the following update from TENET:
The latest report from SEACOM regarding the SMW4 cable repair:

End Update: Please be noted SMW4 repair activity got successfully
completed and all Seacom services came up at 1:40 GMT / 29th April 10.

The SEACOM connection has been up since then, but due to a scheduled
maintenance action in Mumbai we are not yet able to bring the connection
back into service. This maintenance is scheduled to end at 09h30 our
time . As soon as stability is confirmed, the full service will be

Given that some disruption occurred during the transfer from TENET's normal SEACOM link to the backup link on Sunday, it is quite possible that there will be a period of disruption as routing is returned to the normal link.
We've received notification from TENET that routing has been restored to the normal SEACOM link. Access to sites hosted overseas should now have returned to normal.