Loops detected in the network (Nexus 5672UP)

[from88]

Hello,

Has any one seen the issue when Cisco Nexus (Nexus 5672UP) has some strange behaviour - it says that Loops are detected and port-channel are disabled:

2023 Mar 7 19:59:31 NET02A %FWM-2-STM_LOOP_DETECT: Loops detected in the network for mac f8f2.1edc.8c80 among ports Po1419 and Po1422 vlan 903 - Port Po1422 Disabled on loop detection
2023 Mar 7 20:08:55 NET02A %FWM-2-STM_LOOP_DETECT: Loops detected in the network for mac 5cb9.019d.8450 among ports Po1423 and Po2909 vlan 903 - Port Po2909 Disabled on loop detection
2023 Mar 7 20:19:56 NET02A %FWM-2-STM_LOOP_DETECT: Loops detected in the network for mac 5cb9.019d.8450 among ports Po2909 and Po1423 vlan 903 - Port Po2909 Disabled on loop detection

It's quite strange - because the port-channels are totally different and the end devices is not connected to each other. So it's not technically possible for the mac addresses to be looped.
The version we're running is not very old: version 7.3(8)N1(1). We're running straight through VPC connecitivty to servers. The mentioned Loops are detected on both of Nexuses in VPC pair. I've tried to search for Cisco bugs - but unsuccessful.
Can someone help me with this ? Thanks

[MHM Cisco World]

VPC connecitivty to servers <<- 
NSK side you run vPC 
Server side you run teaming PO with lacp or not ??
draw topology please if you can 

[from88]

hello, thanks. 


Nexus side the VPC is running with LACP port-channels. Also the server side is bundled with LACP.

here is the simplified topo:

[MHM Cisco World]

Nexus 2000 Fabric Extenders Supported/Unsupported Topologies - Cisco

there is some platform support and unsupported some topology with FEX 
please check link above 

[from88]

thanks seems it officialy supported: 

Host VPC (Dual Links) and FEX Single Homed (Port Channel Mode) Straight Through VPC Design

[MHM Cisco World]

then last share
show etherchannel summery in both NSK-5

[MHM Cisco World]

vPC Lab of 5K with FEX Device - YouTube

THIS video for steps need for your design 
Note:- LACP can not run between N5K and FEX

[from88]

thanks, actually i dont thin that our topology is not supported. Its quite standard VPC Fex topology. Also i'm adding show etherchannel summery in both NSK-5

[MHM Cisco World]

check video I share, the LACP and pinning must config correctly. 

[from88]

Thanks, we're doing pinning max-links 1 as our default configuration.

[MHM Cisco World]

that why I ask you again, take look in video I share. 
thanks 
MHM 

[from88]

Thanks, i've watched it - everything is clear - i've already configured bunch of Fexes. Was there any special point you wanted to emphasize ?