Is there any data on packet duplication?

Saku Ytti saku at ytti.fi
Tue Jun 23 06:21:10 UTC 2020


On Tue, 23 Jun 2020 at 09:15, Sabri Berisha <sabri at 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.

Hope this helps!
-- 
  ++ytti


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