Re: Using VRF to limit 'ip monitor' and 'iw event' messages

[Ben Greear <greearb@candelatech.com>]

On 5/19/26 17:15, David Ahern wrote:
> On 5/19/26 8:04 AM, Ben Greear wrote:
>>
>> At least many ip events are related to a network interface, so we could
>> add meta data about that to the netlink msg path and then filter
>> before it gets sent to the listener netlink sockets...
> 
> As I recall this problem has been discussed a few times.
> 
> There can be many netlink listeners - e.g., ip monitor, frr, ...
> 
> The lower level code (ie., the one generating the notification) has no
> idea how many sockets will receive the message and which ones will want
> some filter to be applied to the message before attaching to the socket.
> 
> The higher level code (netlink sockets) has no idea of the content of
> the message, so the ability to run a generic filter that is appropriate
> for netlink level is really difficult.
> 
>>
>> Given a network device, is there an efficient way to get the vrf-id
>> to which it belongs?
>>
> 
> yes, that is true for ip route, link, neigh, addr, tc, ... not so much
> for other netlink users.

We have it at least partially working now, it seems like it will not be as bad as I had feared.

For our purposes, filtering most of the unwanted messages should be sufficient, and anything
we cannot easily figure out the ifindex for, we'll just pass on to the socket.

We'll post a patch for consideration once we get some more edge cases sorted out
and some more testing completed.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com