[c-nsp] Bug with IOS-XR and SPAN ports?

[James Bensley]

On 14 December 2016 at 21:48, Hank Nussbacher <hank at efes.iucc.ac.il> wrote:
> We have had a TAC case open for a month and they were able to reproduce
> it just once, where we have been hit by it now twice.
> There seems to be some unknown threshold that needs to be crossed before
> the ingress SPANned port starts losing pkts silently.
> We might very well have to downgrade because of this.

Thanks for the update Hank. I kept this thread marked in my inbox and
was going to ask you if you'd had any progress with it. I simply
haven't had the time of late but some pending QoS testing I have lined
up for ASR9000s might be impacted by said bug so I am curious about
the progress of this issue.

Is it something to do with the central arbiter counting the packets at
ingress twice (once for the "normal" transit packet and once for the
duplicate of the packet made for the SPAN session) so when the SPAN
destination port becomes congested its dropping the ingress traffic
even though the original ingress packet is destined for a different
non-congested port?

Cheers,
James.