From a board design standpoint, What are the categories to consider when picking between an SFP and LAN port. This is to be used as a 1GE management data path so regarding data rates both options suffice. Also please assume only copper cables will be connected to the SFP port.

I'm interested in knowing if there are any benefits in the design of the other pieces of the board, in specific the serial interfaces/phys/switches needed, when picking one of these two over the other.

  • \$\begingroup\$ Apologies for my ignorance, but what does SFP mean? \$\endgroup\$ – Roger Rowland Mar 16 '16 at 18:53
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    \$\begingroup\$ Small form-factor pluggable. They are hot-pluggable transceiver modules that are being used increasingly in data centers(SFP+ and higher data rate modules specially). They have two little ports for receive and transmit. (ROSA, TOSA) Finisar and Avago are two of the largest manufacturer of these products and the documents for the optical transceivers are SFF-xxxx or MSA(multi source agreement) written by the larger companies in this field. \$\endgroup\$ – Arash Mar 16 '16 at 19:36

SFPs generally replace the PHY and magnetics/jack or optical transmitter/receiver and connect directly to the MAC chip or block in your processor. However, the SFP requires SERDES differential pairs (e. g. SGMII or 1000Base-X) from the MAC. If your MAC will only talk GMII or RGMII or such, you'll need a PHY to translate.

The main reason for using SFPs to to allow flexibility to use different interfaces (e. g. copper vs. optical) just be swapping the module in the field.


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