[j-nsp] Debug ip packet equivalent for directed at RE traffic

[Chris Morrow]

At Mon, 28 Nov 2016 19:17:41 +0000,
"Alex K." <nsp.lists at gmail.com> wrote:
> 
> Thank you Tim and Chris,
> 
> But correct me if I'm wrong - those are not quite the same thing.
> 
> There's no doubt packets are reaching the box (I have PC connected directly
> to the switch).
> 
> The difference between traffic monitoring/mirroring and Ciscos' debug, is
> that with debug you follow the path a packet takes.
> 
> Traffic monitoring can be a really helpful first step (as I've said, there
> virtually no doubt the packets are reaching the RE), but my question is
> about - what's next?
> 
> Assumed you see only echo requsts and no replies (by "monitor traffic", for
> example), is there is a trace option to show why an EX decided it shouldn't
> answer with reply (from its own address)?

honestly it's not that hard to tell what went wrong:
  1) route back to the source is broken/unknown
  b) loopback filter dropped inbound packet
  z) ... that's it.

or that's been my experience.