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Subject: Re: [PATCH net-next] ipv4/fib: send RTM_DELROUTE notify when flush
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To: nicolas.dichtel@6wind.com, Stephen Hemminger
 <stephen@networkplumber.org>, Hangbin Liu <liuhangbin@gmail.com>
Cc: Ido Schimmel <idosch@idosch.org>, netdev@vger.kernel.org,
 "David S . Miller" <davem@davemloft.net>, Eric Dumazet
 <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>,
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From: David Ahern <dsahern@kernel.org>
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On 7/28/23 7:01 AM, Nicolas Dichtel wrote:
> Frankly, it's quite complex, there are corner cases.

yes there are.
> 
> When an interface is set down, the routes associated to this interface should be
> removed. This is the simple part.
> But for ecmp routes, there are several cases:
>  - if all nh use this interface: the routes are deleted by the kernel;
>  - if only some nh uses this interface :
>    + if all other nh already point to a down interface: the route are deleted by
> the kernel;
>    + if at least one nh points to an up interface: the nh are temporarily disabled.
> 
> Managing a cache with this is not so obvious 😉


FRR works well with Linux at this point, and libnl's caching was updated
ad fixed by folks from Cumulus Networks so it should be a good too.