changing speed of fiber modules on switches possible ?

- K
- kermit
  
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posted
16 years ago

Mon, Jan 21, 2008 10:31 AM

Hi,

i have a 3560G with 1Gbit Fiber Ethernet SPFs (GLC-SX-MM) and some older 2912MF-XL (with 12 100Mbit Fiber modules).

I simply can not get a connect between these switches. Sure there is

1000BASE-SX on one side and 100BASE-SX on the other side, but i thought the 1GB-module would do autosensing. As far as i can see it is not possible to change the speed of the 1Gbit-SPF to 100 Mbit.

Is there no way to connect a newer Gigabit-switch with an older

100Mbit-Switch via the fiber ports? Is changing the speed of an interface only possible on copper- interfaces ?

I hope someone can explain this to me. Thanks ...

regards J.Hartmann

- B
- Brian V
  
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posted
16 years ago

Mon, Jan 21, 2008 12:21 PM

They are fixed speed 1000. They do not auto-negotiate.

- D
- Doug McIntyre
  
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posted
16 years ago

Mon, Jan 21, 2008 5:35 PM

No, fiber modules in general are not auto-speed sensing. You have to change out the optics to match what you are doing for anything.

You really need a 100-Base-FX SFP for your Gigabit switch to hook them up and have it talk 100-Base-FX back to your old 2912MF-XL fiber module.

Cisco part #GLC-GE-100FX=, list price $250.

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That part should work in a 3560G, you probably will want to double check that first on the data sheet for it.