[c-nsp] Cisco1900 routing packets with destination MAC all zero?

James Bensley jwbensley at gmail.com
Mon May 8 05:46:39 EDT 2017

On 8 May 2017 at 09:57, Saku Ytti <saku at ytti.fi> wrote:
> Hey,
> I'm not sure why this is relevant?

In my head I have just skipped forward a bit, the behaviour is
undefined and probably defaults to accepting it as a broadcast. It’s
very unlikely to be a XEROX OUI destined packet. Up until the point of
my post no explicit MAC filtering (e.g. VACL) has been mentioned and
output of the implicit MAC filter, no config provided either or other
details from the packet except that the DMAC is

So for example, as we know Cisco tend to use a heuristic method for
parsing packet headers, if we can see the packet we have further data
to speculate as to why this packet was parsed and routed/forwarded.
I’m also interested in where it came from, that might help indicate
why the router received it and why it was forwarded, and why it had an
all zero’s MAC, more data is rarely an issue with diagnosis.


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