routerboard 1100 sometimes refuses to route (ICMP-)packets

[Florz]

Hello,

I’ve got a strange problem with a routerboard 1100. It occurred under OS version 4.13 as well as under version 4.16. I try to build a setup for testing network equipment like VPN-routers and DSL based Ethernet bridges for example.
At first I reseted the board, flushed the firewall rules, set up 10 VLANs and bridged them to port 1 to 10. I also set up IP and MAC addresses for the bridge interfaces. Routing works fine between most of the networks but sometimes (I don’t know why) some hosts don’t receive ping replies. I used the packet sniffer in winbox to debug this and I found out that the ping packets were answered by the destination but they were not routed back. I also used Wireshark to confirm this on the sending PC. No answers were received. Pinging the same destination from an other VLAN was no Problem.
After finding out all this, I decided to make a backup and reset the board again. I then setup only a minimal test and tried the same ping. It didn’t work either. I also tried different physical ports at the board.
The setup was as follows:

PC:
-IP 192.168.1.49/24
-default route: 192.168.1.2
-at port 1

Test device 1:
-IP: 192.168.4.120/24
-default route: 192.168.4.2
-at port 4

Test device 2:
-IP: 192.168.2.49/24
-default route: 192.168.2.2
-at port 2

Router:
-RouterOS 4.13 (later updated to 4.16 without any change)
-port 1:
*on bridge 1 (IP: 192.168.1.2/24)
-port 4
*on bridge 4 (IP: 192.168.4.2/24)
-port 2
*on bridge 2 (IP: 192.168.2.2/24)

ping from PC to test device 1:
-router sees outgoing and incoming ICMP packets with identical payload (must be the same ping)
-PC only sees his own sent packets (local Wireshark)
-answers don’t get routed without any noticeable reason

ping from test device 1 to PC:
-arrives at routerboard
-doesn’t arrive at PC

ping from PC to test device 2:
-works without a problem

Please also have a look at the screenshots attached to this post.

Until now nobody was able to help me. So I assume its either a bug or I misunderstood how to configure the router.
An other strange fact to mention is that the problem disappeared after I played around with the IP addresses of the bridges but it unfortunately remained in my real setup. On routerboard 750 (used until routerboard 1100 arrived) problems always disappeared after a reset and playing back the last backup.

What am I doing wrong? How can I help to find the bug? (If it isn’t my own stupidity )
Thanks in advance!

[Florz]

I solved the problem.
The MAC addresses for the bridges turned out to be the problem. I used addresses starting with 01:… which are reserved for groups of devices. I now use “locally administered addresses” beginning with 02:… and everything works as it should.