No ethernet link: how to debug?

RouterOS General
1

I have several routerboards connected to same ethernet switch.
Routerboard are all powered, led switches are on but often I can’t ping devices.


    sent=200 received=144 packet-loss=28% min-rtt=1ms avg-rtt=3ms 
   max-rtt=21ms 
HOST                                     SIZE TTL TIME  STATUS                 
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 2ms  
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
    sent=220 received=156 packet-loss=29% min-rtt=1ms avg-rtt=3ms 
   max-rtt=21ms 
HOST                                     SIZE TTL TIME  STATUS                 
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                                            timeout                
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms  
192.168.81.2                               56  63 1ms

For debugging purposes I use netwatch:


10:19:53 script,info 192.168.83.13 down 
10:20:00 script,info 192.168.83.13 up 
10:21:13 script,info 192.168.83.13 down 
10:21:20 script,info 192.168.83.13 up 
10:22:03 script,info 192.168.83.13 down 
10:22:10 script,info 192.168.83.13 up 
10:24:53 script,info 192.168.83.13 down

In these examples I’m using different IP as example.

Is there a way to debug (using system log messages) to understand what’s happening?
Thanks.

2

Hello

If you have the same problem with all RBs, start by replacing the switch. If it’s only certain routers, swap cabling.

Start with the simple causes before looking for the hard ones :wink:




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3

I set same netwatch on other RBs so I discovered I have same trouble on different subnets; tomorrow I’ll try but I suppose I can’t have 3 switches broken at same time…

4

Then you should describe your setup with more precision. Originally, you only spoke of one switch.

Regards,

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5

If you have stp or rstp on, disable it.

6

I have RSTP on to prevent issues when closing wireless ring, but actually I enable/disable manually the ring. That’s to have a “main” ling to remote station using intermediate repeater; if main link fails I switch to backup but it can happen I have both wireless links active.
Even with RTSP on it has correctly worked for years.
It seems strange I suddenly have same trouble on different networks…
I’ll draw schematic and I’ll post.

7

Maybe you have mixed older and newer ros versions. They have incompatible rstp implementations… Or the problem could be elsewhere of course…

8

Most of my RB has got version 6.19, is it incompatible with newer versions? (or older ones?)
Mmh… are there differences between RSTP of 6.19 and 6.30.4 or 6.36.3?

9

If you disable (r)stp, make sure you have no layer one loops. Then you’ll bring your network down real fast! :wink:

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10

https://mikrotik.com/download/changelogs/current-release-tree

6.38 was the point of change.