Re: [PATCH net-next] ipv4/fib: send RTM_DELROUTE notify when flush fib

From: David Ahern <dsahern@kernel.org>
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>, Paolo Abeni <pabeni@redhat.com>,
	Thomas Haller <thaller@redhat.com>
Subject: Re: [PATCH net-next] ipv4/fib: send RTM_DELROUTE notify when flush fib
Date: Fri, 28 Jul 2023 09:42:10 -0600	[thread overview]
Message-ID: <7e08dd3b-726d-3b1b-9db7-eddb21773817@kernel.org> (raw)
In-Reply-To: <6b53e392-ca84-c50b-9d77-4f89e801d4f3@6wind.com>

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.