Symptom
On a Nexus 9000 series switch which is layer 2 forwarding VPLS transient packets if the destination mac address of the inner frame starts with 4 or 6 the packets will be dropped.This is due to an incorrect software setting on the hardware ASIC.
Workaround
You can also issue the following commands to turn off MPLS processing on the packets and allow them to be forwarded properly:
N9K# attach mod 1
module-1# debug hardware internal dav modify asic 0 slice 0 table tah_dav_prx_cfg_etype 0 1 mpls_disable=1
module-1# debug hardware internal dav modify asic 0 slice 1 table tah_dav_prx_cfg_etype 0 1 mpls_disable=1
Note that this will not persist through a reload, so you can use the following EEM workaround to trigger on box reload syslog and automatically re-apply the above workaround.
event manager applet mpls-fix
event syslog pattern "VDC_MGR-2-VDC_ONLINE"
action 1.0 syslog priority critical msg DETECTED BOX RELOAD. APPLYING MPLS WOR
KAROUND
action 1.5 cli sleep 30
action 2.0 cli slot 1 quoted "debug hardware internal dav modify asic 0 slice
0 table tah_dav_prx_cfg_etype 0 1 mpls_disable=1"
action 3.0 cli slot 1 quoted "debug hardware internal dav modify asic 0 slice
1 table tah_dav_prx_cfg_etype 0 1 mpls_disable=1"
action 4.0 syslog priority critical msg MPLS WORKAROUND APPLIED SUCCESSFULLY
Further Problem Description
This will be permanently fixed in 7.0(3)I4(5) and 7.0(3)I5(2). This SW caveat was specific to Cisco ASIC based N9Ks
