There can be a nasty little problem (you might want to call it bug) that prevents the APIC from discovering the connected Nexus Leaf Switches.
The reason behind it is that after an CIMC Update and/or wipe of the CIMC it can happen that LLDP is enabled on the VIC Card. The problem here is that if it is enabled on the VIC, the LLDP messages get intercepted by the Firmware on the VIC and never reach the APIC Software. So the APIC can’t discover the Leaf’s.
Here’s how to verify this:
No LLDP Neighbors seen from the Leafs:
Leaf101# show lldp neighbors Capability codes: (R) Router, (B) Bridge, (T) Telephone, (C) DOCSIS Cable Device (W) WLAN Access Point, (P) Repeater, (S) Station, (O) Other Device ID Local Intf Hold-time Capability Port ID Total entries displayed: 0
Log on via ssh to the CIMC:
C220-FCHXXXXXXXX# scope chassis
C220-FCHXXXXXXXX /chassis # show adapter
PCI Slot Product Name Serial Number Product ID Vendor
-------- -------------- -------------- -------------- --------------------
1 UCS VIC 1225 FCHYYYYYYYY UCSC-PCIE-C... Cisco Systems Inc
C220-FCHXXXXXXXX /chassis # scope adapter 1
C220-FCHXXXXXXXX /chassis/adapter # show detail | grep LLDP
LLDP: Enabled
C220-FCHXXXXXXXX /chassis/adapter # set lldp disabled
C220-FCHXXXXXXXX /chassis/adapter # commit
Afterwards you power cycle the Server.
Verification that LLDP is no disabled on the VIC:
C220-FCHXXXXXXXX# scope chassis
C220-FCHXXXXXXXX /chassis # scope adapter 1
C220-FCHXXXXXXXX /chassis/adapter # show detail | grep LLDP
LLDP: Disabled
C220-FCHXXXXXXXX /chassis/adapter #
Also, a useful command on the APIC in regards to troubleshooting LLDP/discovery issue is: acidiag run lldptool [in/out] eth2-[1/2]
Thx for the Info Jakub!
The command is really usefull! I’ll add it to the post!