netdev - Re: [PATCH net-next] ipv6: do not merge differe type and protocol routes

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Message-ID: <30d8c41c-2f53-c77f-5584-d93ea2e05b5e@6wind.com>
Date: Fri, 15 Sep 2023 17:58:33 +0200
From: Nicolas Dichtel <nicolas.dichtel@...nd.com>
To: Hangbin Liu <liuhangbin@...il.com>
Cc: David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org,
 "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Ido Schimmel <idosch@...sch.org>,
 Thomas Haller <thaller@...hat.com>
Subject: Re: [PATCH net-next] ipv6: do not merge differe type and protocol
 routes

Le 15/09/2023 à 05:49, Hangbin Liu a écrit :
> On Fri, Sep 01, 2023 at 11:50:12AM +0200, Nicolas Dichtel wrote:
[snip]
>>> + ip route append unicast 2001:db8:103::/64 via 2001:db8:101::10 dev dummy2 table 100
>>> + ip -6 route show table 100
>>> local 2001:db8:103::/64 via 2001:db8:101::10 dev dummy1 metric 1024 pref medium
>>> 2001:db8:103::/64 via 2001:db8:101::10 dev dummy2 metric 1024 pref medium
>>
>> What is the purpose of such a routing table?
> 
> As I replied in last mail. I don't have a clear purpose. A user may use
> the local route to block traffic temporary.
> 
>> How is the gateway of a local route used by the kernel?
> 
> I don't know. IPv6 support this since beginning...
> 
>> Which route will be used when a packet enters the stack?
> 
> The first one it find?
Frankly, it seems strange to me to try to fix a scenario without a clear view of
what is expected. I agree that the current behavior is questionable, but it
enables to keep the system (the routing table) in a clear state.

My two cents,
Nicolas