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Beginner

connectivity problem

dear team,

   in my cisco  WS-C3850-24XS  switch when i connect the sfp module sfp-10g-sr in both end at that 

time the interface shows its connected but the link is not up why?

8 REPLIES 8
VIP Advisor

Re: connectivity problem

"interface shows its connected" what you mean by connected ?

 

as per your screenshot the interface down, 

 

Steps :

 

1. check both SFP are able to detect.

2. check the fibre distance.

3. check the lights in fibre, if you see light in the right connector. ( if not swap the fibre connector)

 

BB

BB
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Beginner

Re: connectivity problem

Inside the sfp module the red light is blinking
Hall of Fame Community Legend

Re: connectivity problem

Are you sure the link is multi-mode? What is the distance between the two?
Have you tried to "shut" & "no shut" the ports?
Beginner

Re: connectivity problem

Yes i do that sh and no shu but its not working
Highlighted
VIP Advisor

Re: connectivity problem

Look at the Fibre as suggested above my post it may be worth trying and see if it fixes the issue.

 

should be like this :

 

        Light    ---------------- (No Light)        

SFP                                                                   SFP

        (No Light) ----------------- light

 

Hope fully we are talking here dark fibre inside campus.

 

BB

BB
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Hall of Fame Community Legend

Re: connectivity problem


@aslulam555 wrote:
Inside the sfp module the red light is blinking

I hope someone has explained or warned about looking into the laser with a naked eye. 

Cisco Employee

Re: connectivity problem

Hello,

 

Cisco SFP-10G-SR module

The Cisco 10GBASE-SR Module supports a link length of 26m on standard Fiber Distributed Data Interface (FDDI)-grade Multimode Fiber (MMF). Using 2000MHz*km MMF (OM3), up to 300m link lengths are possible. Using 4700MHz*km MMF (OM4), up to 400m link lengths are possible.

 

As suggested:

 

  1. Check the link length
  2. Check that you're using Multimode Fiber
  3. Make sure that TX connects to RX at the other for both strands of fiber, specially if those can be swapped and the end of the cable.
  4. Test with a different cable.
  5. Test with a different SFP if you have several available.
  6. Configure two interfaces on the same switch as layer 3 interfaces (no switchport command) connect the SFPs and form then connect the fiber cable between those two interfaces to then check if those come up as expected.

Report your results.

 

Regards,

VIP Advisor

Re: connectivity problem

Hello

Set the port on both sides to autonegotiate the speed/duplex meaning DONT hard code either side, if the mdix is disable use a crossover cable between the two switch's.

 

 

res

Paul



kind regards
Paul

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