u/call0w

▲ 1 r/Cisco

SFP issues - weird little switch

I need to connect an MDF to an IDF switch.

Switch in the MDF is a C1300-48FP-4G

Fiber SFP are FS brand - SFP1G-85-1

We have used dozens of these switches/fiber modules in the past and they work fine.

This is where it gets fun.

For this IDF, I have to install in a wall enclosure. There's no rack and no room for a full size switch.

When I connect the 1300 switch in the MDF to a temporary switch I have in the IDF (a CISCO BUSINESS 250 Series 8 port switch that won't fit in the enclosure), everything works. Fiber link comes up, devices work just fine.

I bought a tiny 4 port PoE+ sfp switch (E-LINK lnk imc104gp sfp - Mini Industrial 4-Port 10/100/1000T 802.3at PoE + 1-Port 100/1000X SFP Ethernet Switch with 12~48VDC Input and Voltage Booster).

When I connect the fiber in the IDF to the E Link Switch (same SFP - works when patched into the CISCO 250 SWITCH) I get no link.

However, if I string everything together and go from MDF Cisco 1300 --> IDF Cisco Business 250 --> E-LINK SWITCH ----> IT WORKS.

I SSH in and see the SFP recognized in the 1300 switch just like the 250, but there is no sign of life when I patch the cable in on the 1300 - but the 250 links right up.

TL;DR - Why can I connect from a Cisco Business 250 to a weird little chinese switch no problem, but a fiber connection (utilising the same cable, the same SFP) from a Cisco 1300 doesn't link up?

Halp?

reddit.com
u/call0w — 3 days ago