I have a 450G running as a multihomed configuration that's connected to my network using a primary wireless and backup DSL link. Both interfaces connect into an existing OSPF routed network at two seperate locations. It runs two seperate OSPF instances on each interface, receiving routes and announcing the connected network on each interface, but not redistributing routes between instances.

However, the device is not installing the desired primary route as the active route in the routing table, and is instead using a higher metric route. I can't find any way to determine routing priority between two disparate OSPF instances.

I suspect this is because both OSPF instances are being treated as the same metric by ROS, and thus whichever route is tagged as active vs the one that's installed but inactive is simply up to random chance. On a Cisco, in this sort of situation, what I'd want to change is the OSPF instance metric or administrative distance of the instance in order to prioritize one instance over another. However, I can't find any way to do this sort of thing. How would I resolve this issue?

I should say that for actual traffic, this route flipping doesn't affect me. The traffic traversing this router is tagged and routed as desired using static routes that a script disables/enables as each OSPF derived route is installed in the table. However, where this is causing problems is the SNMP monitoring of the router. As the SNMP daemon can't be bound to an interface, the src-address it replies as keeps changing and leading to 'no responses', as per http://forum.mikrotik.com/viewtopic.php?f=2&t=54869. Defining a instance to use as the default for internally-generated traffic is what I'm looking to do.

Have you tried artificially adjusting the cost of the link on either side to influence which route you want to be active? You could also look at equal cost multipath - Cisco does this by default for up to 4 equal cost/equal AD routes but it must be manually configured in the MikroTik world.

Link to ECMP wiki:
http://wiki.mikrotik.com/wiki/Manual:IP ... .29_routes

I've adjusted the OSPF interface cost, yes, but that only adjusts it within the OSPF instance. Since one instance has the route to the destination as interarea and the other has it as intraarea, the latter instance always routes to the destination via the intraarea path even though I'd prefer the interarea path.

I'm trying to find a way to adjust the OSPF instance cost, but I can't find one.

ECMP won't work, I'm not looking to load balance. I'm looking for this multipath to be a transparent backup connection to the rest of the network but only used in a backup situation. As mentioned, the only real problem with the current configuration is that intermittently the SNMP daemon will 'stop responding' to queries due to using the wrong src-address, as it routes the packets out over the backup connection and uses an IP that's primarily in use on that link.

To illustrate the issue, I want to define the route to xxx.xxx.224.0/24 via the vlan1 interface to always be active when there's a route from both vlan1 and MultiPPPoE installed. Currently, which route is active is indeterminant.