Hello guys,

I have a Mikrotik CRS326-24G-2S+ running version swos 2.13. I have it for about one month and a half now so it is quite new setup.
I have also installed two 10G SFP+ copper modules and i experience some problems on them. The SFPs are other vendor (aliexpress for mikrotik devices). they are multigig supporting 1Gb, 2.5Gb, 5Gb, 10Gb.

First set of questions: as it can be seen in the image, the two SFPs connect to one nas device with a 1Gb copper port and a Proxmox host with a 2.5Gb copper port.
Why are these ports appearing as being negociated to 10Gb by Mikrotik (or the SFPs ?) when in fact they are 1Gb and 2.5Gb? I checked on the end devices (the nas and the proxmox) and the interfaces on their end are indeed 1Gb and 2.5Gb speed.
For the SFPs, on the mikrotik, if i want to set manual speed on them, i have 10M, 100M and 1G - nothing else, not even 10G which appears in the screen shot. If anyway, i want to set manual to 1G, the port does not come up; only autonegotiation works.
Is the 10G speed displayed in GUI a cosmetic error? If yes, where can i see the real actual port speed negotiated on the SFP ?

Second set of questions: As seen in the picture , there are some errors and tx/rx pauses
1. why does the port towards the NAS (which is 1Gb) is receiving Rx pauses, as it is smaller than the SFP? Is that port sending more throughput than what the SFP (which is 10Gb) can handle? only Rx pauses, not Tx ones; however, besides that, i have no problem with the port, traffic works.
2.the port towards the Proxmox is having no Rx pauses, but it displays a lot of Tx pauses - why so many? I know that the SFP is bigger than the Proxmox 1Gb port, but they should negociate to same speed and no bottleneck should occur, nor interruptions, pauses, etc. Correct?
The Rx/Tx pauses (especially the tx ones) reach those high values in several tens of minutes since a reset occurs.
Now about the errors on the Proxmox port - from time to time (completely random-once per month , or 4 times in a day, or 3 times in one hour, etc), these errors appear; during this, things are not working (very strange because from my laptop i can ping 8.8.8.8 and google.com, but can t open a web page nor anything else internally). If i just unplug and plug the cable back, the counters reset and the connection ofc, gets refreshed and then it works again. I have changed the SFPs between them selves and also the cables, but the behaviour as far as i saw for one day now, is the same.
Why are those Pauses happen, why are they high and should i worry or not?
What can i do about the Rx FCS errors?

Thx a lot.

guys, anyone, any ideeas?

is this a SWOS (2.13) bug? do i need to switch to routerOS ?

for 1. I believe that's the correct behavior. According to the docs https://wiki.mikrotik.com/wiki/Manual:I ... e/Ethernet the pause frames are received on the Mikrotik port (showing up as RX pauses) from the NAS (generating TX pauses) on the other end.

rx-flow-control (on | off | auto; Default: off) When set to on, the port will process received pause frames and suspend transmission if required.

tx-flow-control (on | off | auto; Default: off) When set to on, the port will generate pause frames to the upstream device to temporarily stop the packet transmission.

for 2. it looks like the Mikrotik is generating TX pause frames on the Proxmox port, likely because it can't keep up with forwarding the packets coming from it. IIUC the Mikrotiks have pretty small buffers, meaning that if there is a speed mismatch between the sender (Proxmox, 2.5GBe) and another, slower device (maybe the NAS? 1GBe) then the switch will signal to the sending device so slow down by sending it TX frames.

for 1. I believe that's the correct behavior. According to the docs https://wiki.mikrotik.com/wiki/Manual:I ... e/Ethernet the pause frames are received on the Mikrotik port (showing up as RX pauses) from the NAS (generating TX pauses) on the other end.

rx-flow-control (on | off | auto; Default: off) When set to on, the port will process received pause frames and suspend transmission if required.

tx-flow-control (on | off | auto; Default: off) When set to on, the port will generate pause frames to the upstream device to temporarily stop the packet transmission.

for 2. it looks like the Mikrotik is generating TX pause frames on the Proxmox port, likely because it can't keep up with forwarding the packets coming from it. IIUC the Mikrotiks have pretty small buffers, meaning that if there is a speed mismatch between the sender (Proxmox, 2.5GBe) and another, slower device (maybe the NAS? 1GBe) then the switch will signal to the sending device so slow down by sending it TX frames.

Ok, so:
1 - means the NAS is saying " i send you Tx pause frames and you receive them as Rx pause frames", meaning that the NAS is receiving more traffic than its interface can handle and tells to the switch to slow down sending frames - correct?
2 - Ok, that part i understood
So far i understood that rx/tx pause frames are normal and expected behavior - correct?
Anyway, the real traffic is not reaching 1Gb anywhere in the infrastructure, so i don't understand where it may be a congestion if there is one.

The most important question and problem is the Rx FCS Errors on the Proxmox port; why do they happen and how can i fix them? When they occur, the traffic is not working anymore; i need to manually unplug/plug the cable back.

any ideeas?

anyone....Rx FCS Errors ?