ether2 excessive broadcasts/multicasts, probably a loop

littledpurple · Thu Apr 23, 2020 3:40 pm

Hello there! We have a mixed Mikrotik/Cisco network. Everything works fine, except one thing. When backup on the internet server is processing, Mikrotik shows many "ether2 excessive broadcasts/multicasts, probably a loop" errors. I suspect wrong VLAN configuring on Cisco. Is it possible to send Native VLAN 1 and VLAN 12 both at the same port? Or I missed something on Mikrotik? Here is the network scheme and Cisco config. Thanks!

Current configuration : 1598 bytes
!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname SW_MFC_ds1
!
enable secret 5 /censored/
enable password /censored/
!
username /censored/ privilege 15 password 0 /censored/
ip subnet-zero
!
!
spanning-tree mode pvst
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
!
!
!
!
interface FastEthernet0/1
!
interface FastEthernet0/2
!
interface FastEthernet0/3
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!
interface FastEthernet0/7
!
interface FastEthernet0/8
!
interface FastEthernet0/9
!
interface FastEthernet0/10
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface FastEthernet0/16
!
interface FastEthernet0/17
!
interface FastEthernet0/18
!
interface FastEthernet0/19
!
interface FastEthernet0/20
!
interface FastEthernet0/21
!
interface FastEthernet0/22
!
interface FastEthernet0/23
 switchport mode trunk
!
interface FastEthernet0/24
 switchport access vlan 12
 switchport mode access
!
interface GigabitEthernet0/1
!
interface GigabitEthernet0/2
!
interface Vlan1
 ip address 192.168.1.254 255.255.255.0
 no ip route-cache
!
ip default-gateway 192.168.1.1
ip http server
ip http authentication local
banner motd ^Cauthorized access only^C
!
line con 0
 password /censored/
 logging synchronous
 login
line vty 0 4
 privilege level 15
 password /censored/
 login
line vty 5 15
 password /censored/
 login
!
!
end

mkx · Thu Apr 23, 2020 6:21 pm

Post config of your RB ... in terminal window run command /export hide-sensitive ...

Zacharias · Thu Apr 23, 2020 8:33 pm

Or some RSTP related issue...

littledpurple · Thu Jun 04, 2020 3:04 pm

UPD: The cause of this errors is ProxMox. It sends packets on insane speed to Cisco.

Hello there again. I tried to disable all the interfaces except ProxMox and trunk, tried to make access port out of trunk, tried to disable autonegotiate on Cisco and MT and set 100/Full Duplex on both devices; Even 100/Half Duplex. Tried to turn on autonegotiate on both devices. But I still recieve this error when trying to do a network backup. Interesting thing I saw during network backup execution (Ether 3 is WAN):

Screenshot_2.jpg

Is it the reason of these messages or the result of loop?

ether2 excessive broadcasts/multicasts, probably a loop

ether2 excessive broadcasts/multicasts, probably a loop

Re: ether2 excessive broadcasts/multicasts, probably a loop

Re: ether2 excessive broadcasts/multicasts, probably a loop

Re: ether2 excessive broadcasts/multicasts, probably a loop