SFP vs. SFP+

Richard A Steenbergen ras at e-gerbil.net
Thu Feb 17 18:59:30 CST 2011


On Thu, Feb 17, 2011 at 03:41:28PM -0800, Sam Chesluk wrote:
> Depends on the switch.  Some, like the 2960S and 4948E, have 1G/10G
> ports.  They will, however, not operate at 4Gbps (that particular speed
> was chosen to allow the core components to work for gigabit Ethernet,
> OC48, 2G FC, and 4G FC).

4G SFPs are relatively rare, and only for fibre channel. Multi-rate SFPs 
that do up to 2.5G (for OC48) are a lot more common, but they cost more 
than just a simple 1GE SFP. Since all you can do with Ethernet is 1G or 
10G anyways, "most" SFPs you'll encounter in the field will be the 
cheaper non-multirate kind.

For more information about SFP+, as well as some comparisons between 
different 10G optic types, take a look at:

http://www.nanog.org/meetings/nanog42/presentations/pluggables.pdf

As an update (since this presentation is from Feb 2008), SFP+ is just 
now finally starting to get into 40km/ER reach territory. Supplies are 
limited, as they just very recently started shipping, but they do exist. 
Of course since they moved the electronic dispersion compensation (EDC) 
off the optic and onto the host board, the exact distances you'll be 
able to achieve are still based on the quality of the device you're 
plugging them into. SFP+ is still mostly an enterprise box or high 
density / short reach offering, and XFP is still required for full 
functionality.

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)




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