The simplified design is as per the diagram attached. OSPF configuration is listed below. RouterOS is on the latest version.
R1 is connected to R2, R3 and R4 via VLANs over different physical fibre links.
R2, R3 and R4 are connected to each other via a common VLAN to a switch.
R1 distributes the default route to R2, R3 and R4.
R2 distributes connected and static routes to R1.
R3 distributes connected and static routes to R1.
R4 distributes connected and static routes to R1.
R2, R3 and R4 distributes connected and static routes between each other.
I want to use the "switched" connection as backup default route (via R2, R3 or R4) for R2, R3 or R4 only if their main fibre link goes down.
If I enable "redistribute-default" on the R2 router, the R3 and R4 routers get a ECMP default route via the main fibre as well as via the switched connection, this then load balances the default route traffic, which is not what I am looking for. When checking the OSPF metric in columns, the metrics are different, but the default route is still in ECMP. I have tried changing link costs and priority and the problem persists.
Code: Select all
R1
/routing ospf instance
add disabled=no name=ospf-instance-backbone originate-default=always router-id=10.254.0.1 routing-table=main
/routing ospf area
add disabled=no instance=ospf-instance-backbone name=ospf-backbone
/routing ospf interface-template
add area=ospf-backbone auth=sha512 auth-key=************** cost=110 disabled=no interfaces=vlan4054 networks=10.33.0.76/30 type=ptp
add area=ospf-backbone auth=sha512 auth-key=************** cost=110 disabled=no interfaces=vlan3339 networks=10.33.0.24/30 type=ptp
add area=ospf-backbone auth=sha512 auth-key=************** cost=110 disabled=no interfaces=vlan2666 networks=10.33.0.92/30 type=ptp
R2
/routing ospf instance
add disabled=no name=ospf-instance-backbone originate-default=never redistribute=connected,static router-id=10.254.0.6 routing-table=main
add disabled=no name=ospf-instance-junction originate-default=never redistribute=connected,static router-id=10.254.0.6 routing-table=main
/routing ospf area
add disabled=no instance=ospf-instance-teraco name=ospf-area-backbone
add area-id=9.0.0.1 disabled=no instance=ospf-instance-junction name=ospf-area-junction
/routing ospf interface-template
add area=ospf-area-backbone auth=sha512 auth-key=************** cost=110 disabled=no interfaces=vlan3339 networks=10.33.0.24/30 type=ptp
add area=ospf-area-junction auth=sha512 auth-key=************** cost=200 disabled=no interfaces=vlan1138 networks=10.33.0.48/29 priority=64
R3
/routing ospf instance
add disabled=no name=ospf-instance-backbone originate-default=never redistribute=connected,static router-id=10.254.0.9 routing-table=main
add disabled=no name=ospf-instance-junction originate-default=never redistribute=connected,static router-id=10.254.0.9 routing-table=main
/routing ospf area
add disabled=no instance=ospf-instance-teraco name=ospf-area-backbone
add area-id=9.0.0.1 disabled=no instance=ospf-instance-junction name=ospf-area-junction
/routing ospf interface-template
add area=ospf-area-backbone auth=sha512 auth-key=************** cost=110 disabled=no interfaces=vlan4054 networks=10.33.0.76/30 type=ptp
add area=ospf-area-junction auth=sha512 auth-key=************** cost=200 disabled=no interfaces=vlan1138 networks=10.33.0.48/29 priority=64
R4
/routing ospf instance
add disabled=no name=ospf-instance-backbone originate-default=never redistribute=connected,static router-id=10.254.0.29 routing-table=main
add disabled=no name=ospf-instance-junction originate-default=never redistribute=connected,static router-id=10.254.0.29 routing-table=main
/routing ospf area
add disabled=no instance=ospf-instance-backbone name=ospf-area-backbone
add area-id=9.0.0.1 disabled=no instance=ospf-instance-junction name=ospf-area-junction
/routing ospf interface-template
add area=ospf-area-backbone auth=sha512 auth-key=************** cost=110 disabled=no interfaces=vlan2666 networks=10.33.0.92/30 type=ptp
add area=ospf-area-junction auth=sha512 auth-key=************** cost=200 disabled=no interfaces=vlan1138 networks=10.33.0.48/29 priority=64