Re: [PATCH] udp: increment UDP_MIB_NOPORTS in mcast receive

Rick Jones
2012-10-03T17:39:57Z

On 10/03/2012 07:09 AM, David Stevens wrote:
> Of course. I think our difference is on the definition of
> "receives". I don't think a packet delivered locally due to
> promiscuous mode, broadcast or an imperfect multicast address filter
> match is a host UDP datagram receive. These packets really shouldn't
> be delivered to UDP at all; they are not addressed to this host (at
> least the non-broadcast, no-membership ones). A unicast UDP packet
> that doesn't match a local IP address does not increment this
> counter. A promiscuous mode multicast delivery is no different,
> except that the destination alone doesn't tell us if it is for us.
>
> I think counting these will primarily lead to administrators seeing
> non-zero drops and wasting their time trying to track them down.

I would tend to agree with David on this one. Or they might cease trying
to track them down because they've gotten so many "false positives."

Isn't "meant for me" vs "not meant for me" at the heard of "drops"
versus "discards?"

Once the packet is in the host, is it tagged in some way with "this was
received as promiscuous/whatnot?"

rick