01-13-2022 12:32 PM
I'm replacing a switch and I can't get the trunk link to the core connect.
I'm not 100% sure its not the fiber link to the core, but it was previously working and I traced it with a light pen. There are two available fiber links in this comm room and both don't work.
Config is pretty basic on both ends...
interface TenGigabitEthernetX/X/X switchport switchport mode trunk
Show interface on both ends...
GigabitEthernetX/X/X is down, line protocol is down (notconnect) ... Full-duplex, 1000Mb/s, media type is 1000BaseLH
I wanted a 10G-LR SFP but I thought it might be compatibility so i changed it back to the original 1G-LX SFP for now.
I've swapped out everything I could think of on both ends...
-Swapped the switch
-Swapped the SFP module
-LC/LC fiber - new out of the package
-Tried multiple SFP's (Same on both ends)
I also plugged the switch directly into the core via 10G-LR SFP LC/LC and it worked.
I don't know what else to try other than get someone to run a new fiber link which could be expensive.
Please help with some ideas to try
01-13-2022 12:46 PM
Try setting speed 1G or try no autonegotiation interface command.
01-13-2022 12:49 PM
Hi there,
Given your list of hardware checks, have you tried changing the polarity of the fibre at one end?
cheers,
Seb.
01-13-2022 01:30 PM - edited 01-13-2022 01:35 PM
Hello
@DHGmem wrote:10G-LR SFP but I thought it might be compatibility so i changed it back to the original 1G-LX SFP for now
I also plugged the switch directly into the core via 10G-LR SFP LC/LC and it worked.
FYI - 10G will be Single mode, 1GB can be Single or Multimode
So check to see if you have a compatibility issue, also try crossing the TX/RX pins around
01-14-2022 01:53 AM
Hi
You wrote " I traced it with a light pen", I have never seen that this is working on single mode fiber. I thought it only works for multimode.
And if your fiber is multimode, and the SFP:s are LX (single mode) that will be a problem. It can maybe work for a very short range with 10G, it reaches a bit longer with 1G, so the advice from @balaji to test with 1G is good. Or try with SX.
/Mikael
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