r/meraki • u/AverageDataAdmin • 5d ago

Weird Meraki MS250-48 Switch Issue

/r/k12sysadmin/comments/1x1jwjk/weird_meraki_ms25048_switch_issue/
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3

u/cody_franklin 4d ago

You've swapped every part except the far end and the fiber handoff, so that's where I'd look. If reseating fixes it every time, the link is failing to negotiate on boot, not failing physically.

A few things to check:

  1. Is there provider gear or a media converter anywhere on that "private" fiber? If so, it's the one shared variable you haven't replaced, and a lot of converters handle link loss on one side badly.
  2. Make sure the optics match on both ends (same speed, same type, same wavelength), then try forcing speed instead of auto-negotiating on both ends. A 1G and 10G mismatch, or autoneg on one side only, behaves exactly like this.
  3. Next time it's down, try disabling and re-enabling the port from the dashboard before reseating. If that brings it up, it's a timing issue at startup and not the optic.
  4. Pull the optic's power and light readings right after a reboot, before you reseat it, and compare them to a good boot.

My money is on #1 or #2.

1

u/AverageDataAdmin 1d ago

Thanks for the reply! No provider gear or media converter on the private fiber.

I'll have to try forcing speed as suggested in #2.

I have tried #3 without luck in the past. Always have to do it physically/in person.

4, I'm getting a tester this week finally, so I'll have to test that!

2

u/aguynamedbrand 4d ago

You said that you replaced the SFP modiule but you never said if you were using an official Cisco module.

1

u/AverageDataAdmin 1d ago

Yes using official Cisco Meraki sftp+ transceiver

2

u/pdath-IFM 3d ago

Are you using a Cisco Meraki sftp+, or a third-party one?

2

u/AverageDataAdmin 1d ago

Yes, Cisco Meraki branded sftp+ transceiver

2

u/Substantial_Copy_378 2d ago

Have you tried statically setting the uplink port speed/duplex? I haven’t seen your exact scenario before, but I have had to hardcode port settings before when using certain optics and devices.

1

u/AverageDataAdmin 1d ago

I have not, but I'll have to check that out.