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AnonTikUser
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Routers Experiencing Poor Service Disconnects. SFP Heat Issue? Light tolerance?

Tue Jul 06, 2021 6:34 pm

Hello,


I work for a small fiber-optic ISP and we use MikroTik (hEX s, hAP-ac, RB4011, etc.) as the customer premise equipment. We are seeing some problems pop up after prolonged use, usually around 2-3 years or so, to where several customers are reporting drops, inconsistent or just plain poor service on our older (3 years or so) batch of routers where we utilize the SFP port as the fiber uplink port. We have tried extensive troubleshooting, but nothing that we do seems to work. There are no errors that give any indication as to what the problem is, no errors on any of the interfaces, etc. It does not seem to be a wireless issue, as the issues are not exclusive to wireless, per multiple customer reports. Several/all devices appear to be affected when there is a problem. We have installed the problem routers in other places with reports of similar issues, too. When we swap out equipment for new, the problems disappear. Nevertheless, it is becoming a real (expensive) issue, as we cannot dependably reinstall this failed equipment. We believe this to be a heat issue with the transceiver being the culprit. We are using fs.com 10k transceivers and they get quite hot. This can also be seen from the temperature log of the device. I have seen the temperature rise near or above 70 deg Celsius, which I did not think was even possible, given that is not within operating specifications. Usually, the light dBm levels are higher than (or below, depending on how you look at it) -8, sometimes as high as -4 or even -3, which seems really quite high. We have tried attenuators and there is potentially some promise to those; but, it seems once it gets past a certain point of no return, the devices appear to be not consistently functional. We have tried running tests back at the shop and the CPE seems to work okay, but it could very well be that we are not testing over long enough period of time or running the right tests. I am asking if anyone knows what the operating light levels should be, as I do not see anything posted. While I think attenuators could (and probably do) help, I don't have hard evidence to back this up. I guess I am asking if anyone has experienced something similar, knows a potential solution, or can shed some light on this issue. Any help is appreciated. Thanks.
 
msatter
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Re: Routers Experiencing Poor Service Disconnects. SFP Heat Issue? Light tolerance?

Tue Jul 06, 2021 8:03 pm

The 4011 is reasonble cool The hEX-s could need some cooling support.

viewtopic.php?f=3&t=132258&p=862859&hil ... ot#p671105

In datacentre proactive replacing of equipment is normal and you could monitor the dBfor each connection and if it worsens you could replace the SFP of the client or exchang the router including th SFP.

FS got also SFP that are made for higher operating temperatures so have a look at those.
 
AnonTikUser
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Re: Routers Experiencing Poor Service Disconnects. SFP Heat Issue? Light tolerance?

Thu Jul 08, 2021 10:31 pm

Thanks for the response and reference to the other thread. I have read about this topic a little bit and I still am unable to find a clear understanding of the light tolerances, heat tolerances of the equipment (outside of operating temperature), and whether that is a leading cause of failures (as I suspect it would be). I have thought about monitoring the light levels, and maybe that could be done as a small study, but it becomes a little more difficult on a larger scale (at least for me) -- though having more data could be considered useful. I found a code (on this forum) to reference the Rx Power and maybe temperature could be correlated to that. What it would seem is that the higher the intensity of light, the more the SFP heats up, which in turn heats up the SFP port, causing the equipment to malfunction. My contention is that even while operating within the specified acceptable tolerance, that over a long period of time (years) the port can be damaged or lead to more frequent failures.

I have entertained the idea of adding attenuators everywhere, but I would like more of a basis than an assumption, if possible, of course, before adding them everywhere. We have added attenuators where it is already an issue, and have seen error propagation slowed, but not stopped. Then again, sometimes we don't even see errors, but customers have assured us through troubleshooting that there are noticeable service issues that are fixed when substituting the router. We have swapped out about a quarter of the initial routers that we purchased, which seems like quite a bit in a matter of three years of use. I'm sure we can find further ways to study through trial and error, but wanted to at least entertain this to the forum. We are using https://www.fs.com/products/39177.html? ... &id=224887 and https://www.fs.com/products/39176.html? ... &id=224886 for a transceivers. Is there something else we should be using?
 
mada3k
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Re: Routers Experiencing Poor Service Disconnects. SFP Heat Issue? Light tolerance?

Fri Jul 09, 2021 8:18 pm

For some reason, mixing SFPs and vendors sometimes results i excessive SFP heat - I have still not found a good reason for it (overclocking? wrong protocol? wrong data-bus voltages?)

BiDi's is extra sensitive to high and varying temperatures, I have been told.

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