Re: [lwip-users] Multicast MAC address filtering

[address@hidden]

Am 22.01.2019 um 18:36 schrieb Ivan Warren:
> Lwip friends,
>
> Is there a way for LWIP to register MAC addresses related to IPV4 or
> IPV6 multicast addresses to assist in multicast address filtering by the
> MAC (or possibly by upstream switches when supported - without using
> IGMP snooping - or whatever is used when MLD is used).
>
> The NIC I use has the capability to filter Multicast Mac addresses
> (which can possibly reduce the load). I also have another NIC that is a
> virtualization NIC and can inform upstream switch(es) about the filtering.
>
> Without this, a Multicast MAC destination is basically a broadcast ! (Of
> course, the filtering is probably done in LWIP at this point anyway).
>
> (Or am I just on a wild goose chase ?)

Struct netif has the 2 callback functions for this: 'igmp_mac_filter' 
and 'mld_mac_filter'. These two take IP addreses (each in their matching 
version), but since the mapping is defined, that should work for you?

You should use 'netif_set_igmp_mac_filter()' and 
'netif_set_mld_mac_filter()' to set these callbacks.

For IPv6, note that the 'mld_mac_filter' callback is not called for the 
all-nodes group (if I remember correctly).

Regards,
Simon