Loop between bridged vlans in several routers

p3t3r4x · Fri Feb 28, 2020 3:35 pm

Hello every body, sorry for my english, i have a problem when establishing a vlan connection between several mikrotik routers as described in the attachments image, the problem is that it present a posible loop in bridges interfaces and we can see it when checking the logs of the routers, we can see messages such as: vlan-XXX: bridge port received packet whit own address as source address (6c: b0 : d4: 6b: 5d: 3b), probably loop

Note 1: The system admin need to change you conexion between the differents vlan to resolve the problems that appier.
Note 2: All devices mikrotik (R1, R2, R3) are CRS125-24G-1S model
Note 3: All bridges interfaces take the same MAC address see in the logs (6c: b0 : d4: 6b: 5d: 3b) because these have a attribut "auto-mac=yes"

Questions:
1: This configuration is the best way to setup bridged vlans and trunks?
2: How can I detect the posible loop in the network?

Thanks alot for your help.

The configuration that has been carried out is as follows:

Configuration in R1

#Create the vlans (in ether2 trunk)
/interface vlan add name=vlan-100 interface=ether2 vlan-id=100
/interface vlan add name=vlan-110 interface=ether2 vlan-id=110
/interface vlan add name=vlan-120 interface=ether2 vlan-id=120

#Create the bridges
/interface bridge add name=BR100
/interface bridge add name=BR110
/interface bridge add name=BR120

#Add each vlan to a bridge
/interface bridge port add bridge=BR100 interface=vlan-100
/interface bridge port add bridge=BR110 interface=vlan-110
/interface bridge port add bridge=BR120 interface=vlan-120

#When the ADMIN SYSTEM is working in a VLAN 100 for example, it add you ether3-ADMIN interface to a bridge of this VLAN
/interface bridge port add bridge=BR100 interface=ether3-ADMIN

#Asign a IP address
/ip address add interface=BR100 address=10.10.100.1/24
/ip address add interface=BR110 address=10.10.110.1/24
/ip address add interface=BR120 address=10.10.120.1/24

# Creating DHCP Servers
/ip pool add name=POOL-VLAN-100 ranges=10.20.100.20-10.20.100.50
/ip pool add name=POOL-VLAN-110 ranges=10.20.110.20-10.20.110.50
/ip pool add name=POOL-VLAN-120 ranges=10.20.120.20-10.20.120.50
/ip dhcp-server add disabled=no name=DHCP-VLAN-100 address-pool=POOL-VLAN-100 interface=BR100 
/ip dhcp-server add disabled=no name=DHCP-VLAN-110 address-pool=POOL-VLAN-110 interface=BR110 
/ip dhcp-server add disabled=no name=DHCP-VLAN-120 address-pool=POOL-VLAN-120 interface=BR120

Configuration in R2

#Create the vlans (A in ether2 trunk)
/interface vlan add name=vlan-100-A interface=ether2 vlan-id=100
/interface vlan add name=vlan-110-A interface=ether2 vlan-id=110
/interface vlan add name=vlan-120-A interface=ether2 vlan-id=120

#Create the vlans (B in ether3 trunk)
/interface vlan add name=vlan-100-B interface=ether3 vlan-id=100
/interface vlan add name=vlan-110-B interface=ether3 vlan-id=110
/interface vlan add name=vlan-120-B interface=ether3 vlan-id=120

#Create the bridges
/interface bridge add name=BR100
/interface bridge add name=BR110
/interface bridge add name=BR120

#Add each vlan to a bridge
/interface bridge port add bridge=BR100 interface=vlan-100-A
/interface bridge port add bridge=BR100 interface=vlan-100-B
/interface bridge port add bridge=BR110 interface=vlan-110-A
/interface bridge port add bridge=BR110 interface=vlan-110-B
/interface bridge port add bridge=BR120 interface=vlan-120-A
/interface bridge port add bridge=BR120 interface=vlan-120-B

#Add another ports to a bridge
/interface bridge port add bridge=BR100 interface=ether4
/interface bridge port add bridge=BR120 interface=ether5

#Asign a IP address
/ip address add interface=BR100 address=10.10.100.2/24
/ip address add interface=BR110 address=10.10.110.2/24
/ip address add interface=BR120 address=10.10.120.2/24

Configuration in R3

#Create the vlans (in ether2 trunk)
/interface vlan add name=vlan-100 interface=ether2 vlan-id=100
/interface vlan add name=vlan-110 interface=ether2 vlan-id=110
/interface vlan add name=vlan-120 interface=ether2 vlan-id=120

#Create de bridges
/interface bridge add name=BR100
/interface bridge add name=BR110
/interface bridge add name=BR120

 #Add each vlan to a bridge
/interface bridge port add bridge=BR100 interface=vlan-100
/interface bridge port add bridge=BR110 interface=vlan-110
/interface bridge port add bridge=BR120 interface=vlan-120

 #Add another ports to a bridge
/interface bridge port add bridge=BR100 interface=ether5
/interface bridge port add bridge=BR110 interface=ether4
/interface bridge port add bridge=BR120 interface=ether6

 #Asign a IP address
/ip address add interface=BR100 address=10.10.100.3/24
/ip address add interface=BR110 address=10.10.110.3/24
/ip address add interface=BR120 address=10.10.120.3/24

idlemind · Sat Feb 29, 2020 3:08 am

Switch to the new VLAN aware bridges?

ingdaka · Sat Feb 29, 2020 11:59 pm

I've faced this problem before but was one of my IT that connected 2 access vlan (different vlans) of the switch together!

Loop between bridged vlans in several routers

Loop between bridged vlans in several routers

Re: Loop between bridged vlans in several routers

Re: Loop between bridged vlans in several routers

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