Symptom
- Nexus 9K Tahoe ASIC - Multicast traffic coming in on a VPC expecting to cross the VPC peer-link to go out an egress orhpan port is dropped due to VLAN_XLATE_MISS.
- Expected behaviour is the VPC peer should recieve the traffic.
- VLAN mapping is configured along with features 'features vn-segment' and 'feature nv overlay'.
Conditions
- VLAN mapping is configured along with features 'features vn-segment' and 'feature nv overlay'.
- ISSU is done from 7.0(3)I6(1) to 7.0(3)I7(5) and then EPLD upgrade is done and the line cards reload, the issue is suspected to be a miss-programming because of the reload of the line cards.
- Issue is seen in a chassis setup with multiple line cards.
Workaround
- Remove VLAN mapping.
- Bringing down the one VPC leg (to the VPC peer switch that the orphan port is on) had worked.
- Reload the impacted line card.
Further Problem Description
- The following ELAM capture can be seen on the egress ASIC facing the VPC peer-link for multicast traffic that is dropped due to VLAN_XLATE_MISS:
module-2(TAH-elam-insel6)# report
Initting block addresses
SUGARBOWL ELAM REPORT SUMMARY
slot - 2, asic - 3, slice - 1
============================
Incoming Interface: ii2/1/30
Src Idx : 0x622, Src BD : 0
Outgoing Interface Info: met_ptr 0
Packet Type: IPv4
Dst MAC address: 01:00:5E:00:00:05
Src MAC address: 00:50:56:01:05:AE
.1q Tag0 VLAN: 1883, cos = 0x0
Dst IPv4 address: 224.0.0.5
Src IPv4 address: 172.29.10.51
Ver = 4, DSCP = 48, Don't Fragment = 0
Proto = 89, TTL = 1, More Fragments = 0
Hdr len = 20, Pkt len = 72, Checksum = 0xefc
L4 Protocol : 89
Drop Info:
----------
LUA:
LUB:
LUC:
LUD:
VLAN_XLATE_MISS <--- VLAN translation drop.
Final Drops:
VLAN_XLATE_MISS
