nanog mailing list archives

Re: SFP vs. SFP+


From: Vincent Hoffman <jhary () unsane co uk>
Date: Fri, 18 Feb 2011 10:21:49 +0000

On 18/02/2011 03:04, Frank Bulk wrote:
Are there are any optics that plug into 10G ports but have a copper or
optical 1G interface?  There's some equipment that I'm specing where it is
$10K for a multi-port 1G card, even while I really may only *occasionally*
need a single 1G port and there's a free 10G port for me to use.

Some of the cisco stuff supports a twingig converter module, One tengig
to 2 one gig (and from there a copper or optical SFP)
http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps7077/product_data_sheet0900aecd805bbee3.html

Vince

Frank

-----Original Message-----
From: Richard A Steenbergen [mailto:ras () e-gerbil net] 
Sent: Thursday, February 17, 2011 7:00 PM
To: Jason Lixfeld
Cc: nanog () nanog org
Subject: Re: SFP vs. SFP+

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.




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