SFP module for 100FX

Unanswered Question
Jun 4th, 2009


I've just bought a media convertor that converts from 10/100BaseT to 100FX. Currently I have a fibre connection running form the media convertor to a cisco 6509 switch. What SFP module do I need to buy to connect the fibre?

I have the following on the 6509:

NAME: "1", DESCR: "WS-X6748-SFP CEF720 48 port 1000mb SFP Rev. 1.10"

PID: WS-X6748-SFP , VID: V02,



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rshum Thu, 06/04/2009 - 08:53

Dan, are you trying to connect a 100mbs device to a gig port?

Leo Laohoo Thu, 06/04/2009 - 15:27

Hi Dan,

I'm having trouble understanding your problem/requirement (is it just me or do I need more coffee)? You have a WS-X6748-SFP but what do you want to connect it to in the opposite end? Is it client/appliance that has 10/100 Mbps copper or fiber? Is it 10/100/1000 Mbps copper or fiber?

If the far end is a 100BaseFx then Guido is right, a GLC-GE-100FX will do fine.

If your far end is a 10/100/1000BaseTx then GLC-TX installed into a spare port of your WS-X6748-SFP will work. If your far end is a 1000BaseSX, then


Hope this helps.

dan_track Fri, 06/05/2009 - 00:34


Thanks for your help with this. I'm new to the fibre world so I'm confused about the different types of fibre and whether certain Cisco modules and SFP's can work together. Is there a document to highlight the different types a module can take?



Leo Laohoo Fri, 06/05/2009 - 05:52

Here are some reading materials to get yourself acquainted with different types of fibre optics.

Cisco SFP Optics For Gigabit Ethernet Applications


Cisco Fast Ethernet SFP Modules


Inspection and Cleaning Procedures for Fiber-Optic Connections


Hope this helps your cause.

BrinksArgentina Fri, 06/05/2009 - 06:55

I want to add something:

You can't mix anything.

If you have an 100BASE FX transceiver in one end, you must use multimode cable and patchs (orange) and another 100BASE FX transceiver or SFP on the other side.

Mono mode patchs are yellow. This type of fiber is used for long distance connections.

The most used standars for intra-building connections are 100base FX and 1000base SX.


Leo Laohoo Fri, 06/05/2009 - 17:17

Hi Dan,

Good point from Guido! When you are dealing with Fiber Optics remember they can't/won't autonegotiate with other speed. If you have a 1000BaseFX, then the remote end should be the same.

The GLC-TX, however, is different. Depending on the IOS, you can let the GLC-TX negotiate 10/100/1000 Mbps.

Hope this helps.

agugger Sat, 06/06/2009 - 01:13


On this Module are only 1 Gig SFP supported see “Table 6. Interfaces and Distances Supported by Gigabit Ethernet Modules in the Cisco Catalyst 6500 Series” on the link:


Cisco understands only the listed Converters are supported.

A technical detail is the interfaces are limited so support only this speed.


agugger Sun, 06/07/2009 - 21:43

Hi Guido

Do you have tested these ones?

Your sentence “100BASE-FX ARE supported on WS-X6748-SFP” IS NOT TRUE!

At the first post is the Module:

“NAME: "1", DESCR: "WS-X6748-SFP CEF720 48 port 1000mb SFP Rev. 1.10"

PID: WS-X6748-SFP , VID: V02,” listed! My remarks are related to this module.

In your table are a Note 1 say:

“1 Supported with the WS-X6148-FE-SFP module. Other SFPs are not supported on the WS-X6148-FE-SFP module.”

In this particular Module WS-X6148-FE-SFP IS the SFP 100 supported!

Don't mix the Modules WS-X6148-FE-SFP and WS-X6748-SFP!

They are completely different!

All 61XX modules connect over the parallel bus to any sup.

The 67XX modules connect direct to the Switch Fabric of the Sup720!


Even the GLC-T is only at a speed of 1000M supported. Don't care if Cat OS or IOS.

See table 9 on “Cisco Gigabit Ethernet Transceiver Modules Compatibility Matrix” updated: 6/1//09 @


This matrix is most complete document about all possibilities on all Cisco Catalyst and Router.




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