SDWAN Route Selection Help

[craddockchristopher]

Dear Community,

I am having trouble finding documentation that explains how a CEDGE router in Controller mode chooses routes it receives from both OMP and another Routing Protocol. In Practice, I observe that if a CEDGE receives the same route from OMP and another RP the CEDGE always chooses the OMP route, even though it has the highest AD (251). This suggests there is some other logic at play that overrides the traditional "select the route with the lowest AD" logic. However, I can't seem to find any documentation that explains how or why this is. There is plenty of literature on how OMP chooses between more than one OMP advertisement, but nothing really explaining how it makes its decision if it's forced to choose between OMP and some other RP like OSPF or BGP. Also, does it use a different best path selection process when evaluating routes from different RPs such as EIGRP and OSPF against OMP?

Thank you. 

[Kanan Huseynli]

Hi,

it can be in the dual homed situation where you have two routers and you run IGP/BGP in service VPN. You may get route from another router (yet it can even be via L3 intermediate core switch) with route information that this is OMP> IGP/BGP redistributed rou (DN bit of OSPF / BGP SoO). This type of route has AD of 251+1=252, and it can be installed only when there is no corresponding OMP route.

If your topology is different, please share it with outputs.