----- On Jun 22, 2020, at 11:21 PM, Saku Ytti saku@ytti.fi wrote: Hi Saku,
On Tue, 23 Jun 2020 at 09:15, Sabri Berisha <sabri@cluecentral.net> wrote:
Yeah, except that unless you use static ARP entries, I can't come up with a plausible scenario in which this would happen for NTP. Assuming we're talking about a non-local NTP server, S3 will not send an NTP packet without first sending an ARP. Yes, your ARP will be flooded, but your NTP packet won't be transmitted until there is an ARP reply. By that time MACs have been learned, and the NTP packet will not be considered BUM traffic, right?
The plausible scenario is the one I explained. The crucial detail is MAC timeout (catalyst 300s) being shorter than ARP timeout (cisco 4h). So the device generating the packet knows the MAC address, the L2 does not.
Aaah yes, fair point! Thanks $deity for default timers that make no sense. Thanks, Sabri