[FoRK] serving ~30 TB/month

J. Andrew Rogers < andrew at ceruleansystems.com > on > Fri Mar 17 08:53:19 PST 2006

On Mar 17, 2006, at 7:18 AM, Eugen Leitl wrote:
> A quick question: is it feasible to serve some 30 TByte/month
> (either static files, or streaming video) over a 100 MBit
> Fast Ethernet connection, or will I need 1 GBit? The
> unit of serving is some 1.5 GByte MPEG-4 video.


This is only feasible if you plan on running your link at >90% of  
theoretical capacity 24x7, leaving very little headroom for bursty  
traffic patterns.  As a practical matter, 30TB is almost exactly the  
total real bandwidth of a 100Mbit Ethernet circuit over a month.   
This is assuming that the circuit is full duplex; half-duplex FastE  
will fall short even if the traffic is overwhelmingly in one direction.

One of the advantages of Ethernet is that you can reliably drive it  
up to ~90% of theoretical capacity without too much impact on  
performance.  Many other common L2 protocols can only be driven up to  
around 70% of theoretical.  I have seen FastE driven close to the  
theoretical edge in Internet data centers when the core had enough  
capacity to carry it, so as a data point I can confirm that this has  
been done by others successfully.

That said, if it was my servers that needed to constantly run just  
under the ceiling for 100Mbit, I would upgrade to GigE.  All it would  
take is a little bit of electronic dirt being picked up by the FastE  
wiring to fall below the bandwidth requirements, which I have also  
seen happen.

J. Andrew Rogers


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