Port flapping Sextant G5-HnD

Hardware MikroTik hardware general
1

Hello all,

I have a big problem with the famous port flapping in RouterOS. My installation consists of two Sextant G5-HnD, one of them is connected via Ethernet to an RB750GL the other one to a RB751U-2HnD. Only of the Sextants is making problems. Between the RB751U-2HnD and the error prone Sextant is a 20m fixed installation of CAT7 cable. This cable has already been replace in order to exclude this possible cause of the flapping. The distance between the PoE injector which comes after the 20m fixed installed cable and the sextant is only around 4m long. This is a normal CAT6 patch cable. I’ve tried different patch cables as well…

A few month a go was the inital setup where the first problem occurred. After playing around I managed to get a stable 100MBit connection with a cheap TP Link fast ethernet switch placed after the 20m fixed installed calble. Router OS 6.3 was running on all devices. I thougth this workaround is OK for now as the possible software bug will be fixed. Yesterday I did an upgrade to Router OS 6.7 hoping that the bug was found meanwhile. The update was successful and afterwards my link was stable again with 100MBit.
Now I wanted to remove the switch as it is a fast ethernet one and I need gigabit. Then the strange problems began again. No gigabit connection was possible, always port up and down in the logs… :open_mouth:
I thought placing the fast ethernet switch in between again would give me a stable link. But it was’t so!!! Now I am in a situation where I am not able to get a stable link any more :frowning:
Is my hardware broken?
I tried already to switch off auto negotiation as well. Should I send a supout.rif?

Thanks, Toby

2

Is your network cable with shielded or not shielded connectors?
Try another type network cabel cat5E
I don’t know for sure but try to help you

3

Yes it has shielded connectors(CAT6). The same type of patch cable is in use on the other sextant on the PtP. This one works well…
But nevertheless I can give it a try…
What about the PoE injector? May that be the cause of failure?

4

Are you using the gig poe injector that came with it?
Like this one

http://routerboard.com/RBGPOE

5

Yes I use them. Are they buggy? Which one do you recommend?

6

We had similar issues with the original ones(non shielded), the newer ones are shielded and we have less issues.routeros has issues with gigabit

7

How do I recognize the newer ones? Mine has a solid metal connector like the one on the picture three posts above.

But back to my never ending story. I did test another PoE injector from a Mikrotik BaseBox2(RB912UAG-2HPnD-OUT). Result was the same, port flapping all the time.
Later on my buggy Sextant has been disconnected from power source for an hour I think. Then I tried the old poe injector again. And belive it or not it came up with a stable 1GBit connection :smiley:
24h later still no issues. Things get stranger and stranger… My fear is that another power outage makes the things worse as they were in the beginning :frowning:

Can you think of an explanaiton for that behaviour? Discharging capacitors?