N9K L3 PO always suspends one member port

[m1xed0s]

I am trying to build two standard L3 POs between two N9Ks (running as vPC) and a C9500 stack with 100Gbps ports. The two L3 P2P POs would be used for OSPF peerings later. High-level topology is attached below.

When I enable the Po-1 on both ends, the N9K-1 always has one port, such as P2 suspended. But I do not get any log on the C9K side and C9K just shows 2/0/47 is not connected...Similiar case applies when I enable the Po-2 on N9K-2. The Po1 and Po2 are not configured for vPC on the N9Ks.

2022 Oct 14 01:49:28 N9K-1-SW %ETH_PORT_CHANNEL-5-PORT_SUSPENDED: Ethernet1/2: Ethernet1/2 is suspended

 

I tried to configure the Po 1 and Po 2 just as L2. The same one port suspended situation continues....I tried to hardcode speed to be 100Gbps on N9Ks for the related ports and nonegotiate on C9K ports which made no difference either...

If I removed all the Po 1 and Po 2 configuration on both ends, the four ports on each end would all stay up at 100Gbps. 

Here is the vPC configuration:

vpc domain 1
peer-switch
role priority 10000
peer-keepalive destination 10.10.11.2 source 10.10.11.1
peer-gateway
layer3 peer-router
auto-recovery

Here is the Po1 on N9K-1:

interface Ethernet1/1
channel-group 1 mode active
no shutdown

interface Ethernet1/2
channel-group 1 mode active
no shutdown
!
interface port-channel1
ip address 10.10.10.1/30
no shut

Here is the Po1 on C9K:

interface Port-channel1
no switchport
ip address 10.10.10.2 255.255.255.252
!
interface HundredGigE1/0/47
no switchport
no ip address
channel-group 1 mode active
!
interface HundredGigE2/0/47
no switchport
no ip address
channel-group 1 mode active

Any thought?

Just in case, it is needed, here below are the "show spanning-tree summary" outputs from N9K and C9K.

N9K-1-SW# sho spanning-tree summary 
Switch is in rapid-pvst mode 
Root bridge for: none
L2 Gateway STP                           is disabled
Port Type Default                        is disable
Edge Port [PortFast] BPDU Guard Default  is disabled
Edge Port [PortFast] BPDU Filter Default is disabled
Bridge Assurance                         is enabled
Loopguard Default                        is disabled
Pathcost method used                     is short
vPC peer-switch                          is enabled (non-operational)
STP-Lite                                 is disabled

C9K-SW#sho spanning-tree summary 
Switch is in rapid-pvst mode
Root bridge for: VLAN0001
EtherChannel misconfig guard            is enabled
Extended system ID                      is enabled
Portfast Default                        is disabled
Portfast Edge BPDU Guard Default        is disabled
Portfast Edge BPDU Filter Default       is disabled
Loopguard Default                       is disabled
PVST Simulation Default                 is enabled but inactive in rapid-pvst mode
Bridge Assurance                        is enabled
UplinkFast                              is disabled
BackboneFast                            is disabled

[m1xed0s · Accepted solution]

Mystery resolved...The cause is miss-cabling...N9K-1 Eth1/2 is physically connected to C9K port assigned for Po-2.