noticeboard.ru.ac.za

2010/07/18-22 - Internet Quotas Affected By Seacom Outage
As you're probably aware, the SEACOM submarine fibre optic cable that provides us with international Internet access failed on 5 July. The fault has not yet been repaired, and SEACOM currently anticipate that it'll take until at least 22 July before the cable is properly restored.

In order to restore our Internet connectivity, TENET managed to secure us limited temporary capacity from other providers. At present we have a bit under half our normal international Internet bandwidth available to us, and there's an onus on us to reduce our consumption accordingly. Thus far, the measures we have put in place to do this appear to have been working.

However, with the return of students and the start of term, we expect the demands on this bandwidth to increase substantially. To mitigate this, we'll be making some preemptive changes to the Internet quota system to address the increased demand we anticipate.

Starting Sunday 18 July, all Internet quotas will be temporarily HALVED until such time as SEACOM is fully restored. Details of how this will be implemented (including the effects on demand-side management) are available below.

If we're to avoid further restrictions, we have a collective responsibility to be conservative in our use of international bandwidth over the coming week. You are therefore asked to limit your use of international Internet access to essential, business-critical functions, particularly during working hours and in the early evening. You should also avoid bandwidth-intensive applications (e.g. large downloads, streaming audio & video, online radio stations, and Skype & other peer-to-peer or file-sharing applications see https://www.ru.ac.za/quota/counts for more information).

As always, further updates (including any subsequent changes to quotas) will be published on our noticeboard. You're encouraged to check the noticeboard regularly to ensure you're making informed decisions about your Internet use.
We'll be implementing this change by altering the demand-side scaling factors as follows:
  • 08:00-16:59 scale factor of 2.0 (i.e. each MiB you transfer will count two MiB towards your quota)
  • 17:00-22:59 scale factor of 1.0
  • 23:00-07:59 scale factor of 0.5
The net affect of this is to halve your quota during working hours.

These changes apply to both per-user and per-host Internet quotas, and are effective from 08:00 on Sunday 18 July 2010 until further notice.

We're well aware that this will likely be a most unpopular move. However, given the status quo, it is unavoidable. It is also one of the less restrictive options we've considered, as well as the simplest and least disruptive.

Cognisant of the impending return of students at many institutions, TENET is trying to urgently secure more restoration capacity. It is unclear at this stage, however, how much additional capacity might be available or affordable (with many ISPs affected by the SEACOM outage, the cost of temporary bandwidth on other cables has skyrocketed). The most recent information we have available to us does not look hopeful it seems unlikely that they'll succeed in doing this. However, if and when this happens, we'll review the status quo and may consider making some adjustments to the above scale factors.

In the same way, we will continue to monitor the situation closely particularly Rhodes' use of international bandwidth and the aggregate use of all the institutions TENET serves. If there's a chance of making the above scale factors more favourable, we'll consider doing so.

Any such changes, positive or negative, will be published here. Changes might happen at short notice, so check before making assumptions. At the very least you should expect some form of restriction to remain in place until such time as SEACOM is fully restored.
Note that, when evaluating requests for quota credits during this period, two questions we'll be asking in respect of transfers utilising international bandwidth are:
  • whether you could [have] reasonably wait[ed] until after SEACOM is restored.
  • whether the transfer was/is in fact business-critical i.e. that there was no other way for you to achieve this.
You can expect applications that don't meet these criteria to be turned down.
TENET have managed to secure some additional international bandwidth during working hours courtesy of MWeb. As a result, we've reduced the previously announced 08:00-16:59 scale factor from 2.0 to 1.5 (i.e. each MiB you transfer will now count one and a half MiB towards your quota). This is effective immediately.
For tonight at least, the scale factor for the 23:00-07:59 period has been set to 0.2.
QUOTE(guy @ Jul 19 2010, 10:13 PM)
For tonight at least, the scale factor for the 23:00-07:59 period has been set to 0.2.
Assuming there are no major changes in behaviour, these values will apply until the SEACOM problem is resolved.
QUOTE
SEACOM is pleased to confirm that the physical repairs to the fault on the submarine cable are in the final stages of completion with the entire system currently undergoing testing before the cable is lowered back into the water. Our technical teams are actively working with all customers to reinstate their SEACOM traffic to pre-outage configurations and all connectivity going out of Africa is expected to be fully restored on 23 July 2010.

The current restrictions will remain in place until this restoration is complete -- we'll post confirmation here once we know this has happened.
SEACOM was restored at 06:30 this morning. Normal term-time demand-side management values apply from 07:00.
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