SANReN is here…and old news

Published June 10, 2010 by soren

There haven’t been any blog updates so far this year — a lot of things have been keeping us pretty busy, with the new Richard’s Bay CBD campus and all.

However, the University has switched from TelkomInternet to a dark fibre connection to SANReN from the start of February 2010.  This has been a huge improvement — our Telkom Internet connection was 2Mbps, of which 1.5Mbps was guaranteed for overseas traffic.

Well, since SANReN has gone live, our daytime peak traffic is 40-60Mbps, with 25-30Mbps of International bandwidth being used on our SEACOM partition.  This is a clear indication of how bad things were before — we’re using 20-to-30 times our previous capacity.  This can only mean that we’re using the Internet for things that we just couldn’t previously do.

How much capacity do we have?  Our dark-fibre circuit connection to SANReN is 10Gbps, or 10,000Mbps (or, for those of you with ADSL at home, is about 27,000 Home ADSL384 connections). This is 10x the speed of our backbone network on campus, which is currently the limiting factor for speed of downloads on the SANReN backbone.  During tests in early February, we had download speeds to our test machine of 720Mbps, or downloading an entire CD-ROM image in roughly 8 seconds.  Downloads from the TENET mirror service ( to desktop machines are still frequently at speeds of 75-80Mbps (which is very close to the 100Mbps speed of our desktop network ports).

International traffic is currently limited to 50Mbps, but we haven’t hit that limit yet.  International bandwidth is still the expensive component of the costs, but we have 30x what was previously available for approximately twice the cost.

Better news is that an increasing number of services such as google (search, gmail, video, maps, earth, youtube) and other “content distribution network” providers are peering with SANReN.  Most of our google services traffic now flows out of Cape Town — which means that a lot of search and video content is coming over the SANReN backbone where we currently enjoy huge amounts of spare capacity.

It’s fascinating to watch the patterns and destinations of our web traffic — we’re busy with some monitoring and visualisation tools for keeping a handle on how our systems are performing (and what they are being used for!).  Here’s a sample screenshot of a webpage that shows a world map of a snapshot of all outgoing connections to the WWW from staff machines on campus — in this particular snapshot there are 419 active connections…to about 50 different destinations, of which about half are plotted on the map).

proxy server connections

The numbers for WWW usage from campus are quite significant — during the daytime peak, at any instant, there are probably 350-400 active (as in data currently flowing) users with 700-900 concurrent open connections.  This is generating about 150Gbytes of incomming traffic per day (which is the equivalent of 4500 HomeADSL 384 1Gbyte TelkomInternet accounts monthly).

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