[c-nsp] A9K SPAN behavior

[Jason Lixfeld]

Hi,

While troubleshooting a reachability problem, I configured a PW SPAN session on the upstream A9K (XR 4.3.4 & Trident based SPAN source port) but noticed that it didn't actually mirror all traffic.  As a test, I inserted an ME3600, in bridge mode, in between the source host and the upstream A9K, then did the span on the ingress ME3600 port instead.  At that point, I saw the traffic that was missing on the A9K.  Analyzing the missing traffic revealed an invalid destination MAC address.  I'm presuming that the invalid destination MAC address caused the A9K to drop the packet before it was mirrored.  That said, my understanding of SPAN is that a box will always mirror the packet before processing it, so I should have seen the packet on the A9K span session if this had been the behaviour.  Am I off?

Thanks!