Cisco mini-GBIC replacing "RJ45 to Optic converter"

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Apr 26th, 2012
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Hi all

First post, so please be gentle...

We are planning to change the current infrastructure of one of our clients.

As part of this process we are replacing “RJ45 to Optic Fibre converters” with “Cisco mini-GBICs”.

In the attached PDF file you will see 2 examples.

Example 1 represents the current client setup

In Example 2 we have replaced the branch office “RJ45 to Optic Fibre converter” with a Cisco MGBSX1 connected to the Cisco SG300

However this does not work, the Cisco SG300 never boots up correctly and after connecting the Fibre to the Mini-GBIC, the Cisco switch System LED just keeps flashing.

I suspect for this to work we also need a Mini-GBIC connected to the HP Procurve2510 replacing the “RJ45 to Optic Fibre converter” in the Main office!

Is anyone able to confirm this?

If this is not the problem, what else could we be doing wrong?


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Marvin Rhoads Thu, 04/26/2012 - 18:38
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Is your converter 100 Mbps? If so, that'll give you an unsuccessful setup.

Fiber transceivers are fixed speed and have no autosense feature or speed selection - they must be the same speed at each end - 1 Gbps given your use of the mini-GBIC you cited.

The HP switch can use a mini-GBIC in either of the dual personality ports and, in your setup, that's what you'd need. All of the regular copper ports are strictly 10/100 Mbps.

Your fiber link also needs to be multimode and no more than 500m per this Cisco info page.

walter baziuk Wed, 05/23/2012 - 19:04
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most fibre sfp are 1 gb/s and fixed speed

100 mb/s fibre was not very common

at was stated by Marvin. fibre speeds are fixed and can't be changed by command

100 mb/s and 1 gb;/s are not interchagbeale or compatiuble

this is unlike CU connections


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