31 Aug
2015
31 Aug
'15
12:37 p.m.
On Mon, 31 Aug 2015 12:12:16 -0400, Chris Marget said:
At first, I thought this was a bug, but then learned that RFCs 1112, 1122 and 1812 all specify that ICMP unreachables not be sent in response to multicast packets.
I'm struggling to grok the rationale behind not sending unreachables in response to multicast packets. It seems to me that our networks put IPv4 multicast speakers in a position where it's impossible for them to do the right thing.
For the exact same reason that replying to an ICMP Echo Request sent to your broadcast address is generally considered a Bad Idea. The obvious solution is "Doctor, it hurts when I do that" "Don't do that anymore". Don't send multicast packets with DF set.