In scenario when need publishe an internal service via two ISP with static route I have to published an internal services via different public IPs. If need set on of ISP as primary and for this use distance it creates a problem with RPF (Reverse Path Forwarding). In static routing a solving easy - set the same distance for both DG (Default Gateway) and on second DG set more higher priority. In Route Table appeared the default route for second ISP and RPF will not block outgoing packages.
Scenario when DG come from ISP via BGP I can't set which DG is the best. If I use weight or local preference one of DG disappeared from the Route table and RPF drops all package that outgoing via second ISP. In this case which DG comes first, that is the best route.
The priority is avaliable only for static routing, maybe there is a same option for BGP?
Increase path (set-aspath) looks like less flexible. For implementing SD-WAN need go through the bureaucratic hell.
When you put two static default routes with or without different priority values, BGP default routes coming from your ISP wouldn't go in RIB because of admin distance difference, even without you filtering those out with route-maps. That's what I would suggest.
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