From: David Ahern <dsahern@gmail.com>
To: Ido Schimmel <idosch@idosch.org>, Qiwei Wen <wenqiweiabcd@gmail.com>
Cc: netdev@vger.kernel.org
Subject: Re: Multicast routing: wrong output interface selected unless VRF default route is added
Date: Tue, 23 Jun 2020 19:14:28 -0700 [thread overview]
Message-ID: <891caeb6-9c1f-d79d-caa6-23aba7e4d0c7@gmail.com> (raw)
In-Reply-To: <20200623183835.GA69452@shredder>
On 6/23/20 11:38 AM, Ido Schimmel wrote:
>>
>> My questions are:
>> 1. is fib_lookup supposed to work with multicast daddr? If so, has
>> multicast routing been working for the wrong reason?
yes; it is a quirk with Linux routing. see the code after fib_lookup in
ip_route_output_key_hash_rcu. perf can show you the call chain that gets
to that lookup if you want the details.
>> 2. Why does the addition of a unicast default route affect multicast
>> routing behaviour?
>
> I believe this was discussed in the past. See:
> https://lore.kernel.org/netdev/20200115191920.GA1490933@splinter/#t
>
prev parent reply other threads:[~2020-06-24 2:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-21 23:19 Multicast routing: wrong output interface selected unless VRF default route is added Qiwei Wen
2020-06-23 18:38 ` Ido Schimmel
2020-06-24 2:14 ` David Ahern [this message]
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