On 13/04/2022 11:51, Joachim Wiberg wrote: > On Tue, Apr 12, 2022 at 20:37, Nikolay Aleksandrov <razor@xxxxxxxxxxxxx> wrote: >> On 12/04/2022 20:27, Joachim Wiberg wrote: >>> [snip] >>> From this I'd like to argue that our current behavior in the bridge is >>> wrong. To me it's clear that, since we have a confiugration option, we >>> should forward unknown IP multicast to all MCAST_FLOOD ports (as well as >>> the router ports). >> Definitely not wrong. In fact: >> "Switches that do not forward unregistered packets to all ports must >> include a configuration option to force the flooding of unregistered >> packets on specified ports. [..]" >> is already implemented because the admin can mark any port as a router and >> enable flooding to it. > > Hmm, I understand your point (here and below), and won't drive this > point further. Instead I'll pick up on what you said in your first > reply ... (below, last) > > Btw, thank you for taking the time to reply and explain your standpoint, > really helps my understanding of how we can develop the bridge further, > without breaking userspace! :) > >>> [1]: https://www.rfc-editor.org/rfc/rfc4541.html#section-2.1.2 >> RFC4541 is only recommending, it's not a mandatory behaviour. This >> default has been placed for a very long time and a lot of users and >> tests take it into consideration. > > Noted. > >> We cannot break such assumptions and start suddenly flooding packets, >> but we can leave it up to the admin or distribution/network software >> to configure it as default. > > So, if I add a bridge flag, default off as you mentioned out earlier, > which changes the default behavior of MCAST_FLOOD, then you'd be OK with > that? Something cheeky like this perhaps: > > if (!ipv4_is_local_multicast(ip_hdr(skb)->daddr)) > BR_INPUT_SKB_CB(skb)->mrouters_only = !br_opt_get(br, BROPT_MCAST_FLOOD_RFC4541); Exactly! And that is exactly what I had in mind when I wrote it. :) Thanks, Nik > > > Best regards > /Joachim
