Jumbo frame is not works
bridge2 has 1 port, they all set MTU 2000
here is the result.
[root@MikroTik] /interface bridge> pr
Flags: X - disabled, R - running
1 R name="bridge2" mtu=2000 actual-mtu=2000 l2mtu=9014 arp=enabled arp-timeout=auto mac-address=XX:XX:XX:XX:XX:XX protocol-mode=rstp priority=0x8000 auto-mac=yes admin-mac=00:00:00:00:00:00 max-message-age=20s forward-delay=15s
transmit-hold-count=6 ageing-time=5m
[root@MikroTik] /interface> pr
Flags: D - dynamic, X - disabled, R - running, S - slave
# NAME TYPE ACTUAL-MTU L2MTU MAX-L2MTU MAC-ADDRESS
0 RS ;;; Lan
eth2 ether 2000 9014 XX:XX:XX:XX:XX:XX
[root@MikroTik] /ip address> pr
Flags: X - disabled, I - invalid, D - dynamic
# ADDRESS NETWORK INTERFACE
3 192.168.3.2/32 192.168.3.0 eth2
5 192.168.3.1/32 192.168.3.0 bridge2
[root@MikroTik] /ip address> /
[root@MikroTik] > ping 192.168.3.2 interface=bridge2 size=1500 do-not-fragment count=2
SEQ HOST SIZE TTL TIME STATUS
0 192.168.3.2 1500 64 0ms
1 192.168.3.2 1500 64 0ms
sent=2 received=2 packet-loss=0% min-rtt=0ms avg-rtt=0ms max-rtt=0ms
[root@MikroTik] > ping 192.168.3.2 interface=bridge2 size=1501 do-not-fragment count=2
SEQ HOST SIZE TTL TIME STATUS
0 packet too large and cannot ...
0 192.168.3.2 576 64 0ms fragmentation needed and DF set
sent=1 received=0 packet-loss=100%