SFP ports used in Switches

[Thomas Panicker]

Hi ,

We are planning for fiber cabling/connectivity between our two office locations. Please see the below attached diagram.

As of now the distribution switch (3750) is connected to access layer switch (2960) via SFP 1000BASE-SX port. According to the new plan one more SMB switch (SG300-20) is inserted between the previous mentioned switches.

1) I have checekd the specs for SG300-20 but only could find that there will be SFP/mini Gibic port, couldn't identify which ethernet base could be the one in SG300-20 (either 1000BASE-SX/LX/LH etc..). Will the connectivity work if the ethernet ports are mismatching in two ends (ie. one end 1000BASE-SX and other end 1000BASE-LX)? Also how to find the SFP module in the switch SG300-20 which we plan to buy (Could we recomend for 1000BASE-SX itself) ?

2) If we are going with 1000BASE-SX ethernet SFP port will it support Single mode fiber optic cable (We will be having a distance of 520m between the SG300 and C2960 switches so is it advisable to go with Multi mode fiber optic cable)?

Thomas

[graham smart]

Im pretty sure that you cant have one end LX and the other SX .. You would end up with an attenuation issue..

For that distance  you will need LX at both ends.

(1000BASE-LXc an also run over all common types of multi-mode fiber with a maximum segment length of 550 m )

[Thomas Panicker]

Hi Graham,

Thanks for the update. I went through Cisco site checking specs for SG300-20 but couldn't find which SFP ports are being used in the same. Any idea regarding the same ?

[Durga Prasad M.S · Accepted solution]

You need a MGBLX1 module for the sg 300.
This is single mode. The corresponding module on the classic cisco would be the LX module.
Though the supported distance for multimode is 550 m on the 50 micron singlemode. If you have older multimode i.e. 62.5 then the distance is much lower. You definately have to plan for losses on the fiber.
Naturally single mode becomes the preferred choice.

Rgds/dp


Sent from Cisco Technical Support Android App

[Thomas Panicker]

Hi Durga,

Thanks for the infornation. One doubt do the switch sg300 comes with pre installed sfp module or it should be procured additionally as per or requirement?? And if we are going for the LX mode then what should be the connector which we should go for LC or SC?

Thanks in advance.

Thomas

[Reza Sharifi]

Hi,

For SFP optic, you always use LC.  So, according to your diagram in your first post, you need LC to LC Single Mode patch cord from the 2960 to sg300. and LC to LC Multimode patch cord from sg300 to 3750G.  SC type connectors are used for X2 optics.

I am not familiar with sg300 series, but most likely you have to purchase the module.

Talk to your sales guy on this one.

HTH

[Durga Prasad M.S · Accepted solution]

Hi Thomas,

The switch does not come with any modules preinstalled. you buy the modules as required. i.e singlemode or multimode.

for all SFP modules the connector is LC type.

pls rate useful posts and mark question as answered if you are satisfied so that it is useful to others.

Regards/DP