Thread (59 messages) 59 messages, 10 authors, 2012-10-04

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

From: Rick Jones <hidden>
Date: 2012-10-03 17:39:57

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
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