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OPERATIONAL DEFECT DATABASE
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Traffic for certain flows coming into the leaf switch (N9K-C93180YC-FX3) from fabric ports (uplinks) may get dropped. This is due to incorrect internal lookups that result in packets being misclassified and handled incorrectly.
The egress leaf switch for traffic flow is a N9K-C93180YC-FX3 switch.
This workaround needs to be applied on any N9K-C93180YC-FX3 switch that may be affected by this defect. This workaround is not persistent, if the leaf switch is reloaded it must be re-applied. Contact Cisco TAC if you are not comfortable running these commands. - Log on to the leaf switch using the CLI and enter linecard mode: # vsh_lc - Use the following command to verify the following values ("slice port" "srcid") for the uplink ports: # show platform internal usd port info > They should look like this: Port 17.0 (Eth1/49) : Admin UP (1) Link UP Cfg_Fec RS CL91 Fec RS CL91 Fcot Copper retimer 0x1610 AN_knob No AN_cfg Yes AN_operSt No In_debounce 0, Debounce-Time 0 usecs qsa: No EMI Enable:No slice:0 slice port:16 lcl srcid:32 gbl srcid:32 > Here are the values per uplink port that must be verified: Eth1/49 - slice port:16 lcl srcid:32 Eth1/50 - slice port:20 lcl srcid:40 Eth1/51 - slice port:8 lcl srcid:16 Eth1/52 - slice port:12 lcl srcid:24 Eth1/53 - slice port:0 lcl srcid:0 Eth1/54 - slice port:4 lcl srcid:8 - If these values match you can proceed with applying the workaround for each uplink. If they do not match, contact Cisco TAC. - If you have converted any downlink ports into uplink ports, contact Cisco TAC. - Only the uplinks that are utilized require the workaround although it can be applied to all. - One command is used to apply the workaround to each uplink: Eth1/49: # debug platform internal sun mod table roc_sun_prx_cfg_port_config 16 1 prx 0 udf_pif_label=0x1 Eth1/50: # debug platform internal sun mod table roc_sun_prx_cfg_port_config 20 1 prx 0 udf_pif_label=0x1 Eth1/51: # debug platform internal sun mod table roc_sun_prx_cfg_port_config 8 1 prx 0 udf_pif_label=0x1 Eth1/52: # debug platform internal sun mod table roc_sun_prx_cfg_port_config 12 1 prx 0 udf_pif_label=0x1 Eth1/53: # debug platform internal sun mod table roc_sun_prx_cfg_port_config 0 1 prx 0 udf_pif_label=0x1 Eth1/54: # debug platform internal sun mod table roc_sun_prx_cfg_port_config 4 1 prx 0 udf_pif_label=0x1
This bug results in frames received on the leaf uplinks to be parsed incorrectly. Specifically, its been seen that the first byte of the inner dst mac address may not be parsed correctly, resulting in wrong decisions when going through the forwarding pipeline. This is why the issue may be seen with some destination mac addresses, but not others.