Friday, February 03, 2012

The inexorable growth of bandwidth, or lack thereof

I moved offices recently, so I threw away some old posters.  One of them was an old map of the GÉANT backbone.  On a first look, I was wondering how old it was - the main backbone links were all 10Gb/s, much like today (a few links have been updated to 2-3*10Gb/s or 40Gb/s last year).  To my surprise, the poster was from 2001.  So for ten of the last eleven years, the standard backbone link capacity for large research backbones has stagnated at 10 Gb/s.  (I know other things have changed... these things have become more "hybrid" and stuff.)
In a similar vein, the standard network interface for a standard 1RU or 2RU rackmount server has been Gigabit Ethernet (1Gb/s) in 2001, and it is still GigE in 2012 - although servers generally have at least two and commonly four of them.  You can get servers with 10GE interfaces, but this is not the norm.
The main reason is probably that the upgrades to 10Gb/s or GigE in 2001 were "too early", or based on too optimistic assumptions of future growth.  Anybody remember Sidgmore's law?
But I think that demand has eventually caught up, and that we're on the brink of moving beyond these steps.  For servers, it seems clear that GigE will be replaced by 10GE.  For this to happen, it needs to be on the motherboard, and probably in the twisted-pair variety.  For backbones, the preferred option in most circles seems to be to move to 100GE.  Personally I think that 40GE or even 10GE, in connection with link bundling (as is already done in the commercial world) could be interesting alternative options, also for research networks.

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