VLAN flapping between ports

[Sarah.Hussein]

Hello,

I have N5K-C5548P and configured keepalive link between 2 SWs ,, as L3 then I got an issue,, after troubleshooting and search, the solution was either install LAN_BASE_SERVICES_PKG license or L2 Interface mit int vlan ,,, I did the second option and got flapping

2024 Jun 6 12:17:47 SW-B %FWM-6-MAC_MOVE_NOTIFICATION: Host 547f.ee25.xxxx in vlan 123 is flapping between port Eth1/9 and port Po1

For sure, due to the loop

HYG the config:::

interface Ethernet1/9
description VPC KEEPALIVE
switchport access vlan 123
speed 1000

!

interface port-channel1
description vPC-PeerLink
switchport mode trunk
no lacp suspend-individual
spanning-tree port type network
speed 1000
service-policy type qos input PM-QOS-TRUST
vpc peer-link

!

interface Vlan123
no shutdown
vrf member keepalive
ip address 10.0.0.2/30

[MHM Cisco World]

it simple 
remove VLAN 123 from Peer Link
switchport trunk allowed vlan remove 123

this VLAN use only as keepalive not as vpc VLAN 

MHM 

[Sarah.Hussein]

I have done that already but no luck

I removed the vlan 123 then shut and no shut for E1/9 but same issue

!

SW-A# sh vlan id 123

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
123 KEEPALIVE active Eth1/9

VLAN Type Vlan-mode
---- ----- ----------
123 enet CE

!

SW-A# sh int e1/9 status

--------------------------------------------------------------------------------
Port Name Status Vlan Duplex Speed Type
--------------------------------------------------------------------------------
Eth1/9 VPC KEEPALIVE notconnec 123 full 1000 SFP-1000BAS

!

[MHM Cisco World]

can I see 
show vpc brief 

MHM

[Sarah.Hussein]

okay,

please check the attached photo

[MHM Cisco World]

I will assume that PO90 also not allow vlan123 

Can you check the STP' it can it but the port into bridge assurance (BA)

MHM

[Sarah.Hussein]

so, which ports should vlan123 added to? 

Noting that it was up the day of config and after 10 days, suddendly it became down (so I will check also if this is a physical issue)

[MHM Cisco World]

so, which ports should vlan123 added to?

Answer:- Only e1/9 this special vlan use for keepalive not for other data traffic.

Noting that it was up the day of config and after 10 days, suddendly it became down (so I will check also if this is a physical issue) 

Answer:- I see notconnec in show you share' this mainly see if there is l1 issue like speed' but I dont care since the mac is seeing flapping i.e. there is traffic pass e1/9 so it connect' correct me if I am wrong 

MHM

[MHM Cisco World]

FYI I already run lab and allow vlan in peer link and immediately keepalive is down when I remove it the keepive is UP and peer is reachable.

So friend step by step check' check l1 then check allow of vlan.

MHM

[Sarah.Hussein]

strange, I tried same ports but not solved ,, I changed the ports to e1/31 with no config ,,, no shut ,, then speed 1000 ,, also got not connected,,,,, so i guess it is L1 issue OR there is a licence to be added (because the default config that the port is assigned to VLAN1 ,,, when I write no switchport ,,, I got in the output (2024 Jun 24 15:30:25 HHLOKNET-NDFC-POC-A %ETHPORT-5-IF_DOWN_L3_NOT_READY: Interface Ethernet1/31 is down (L3 not ready))

[MHM Cisco World]

https://community.cisco.com/t5/data-center-switches/ethernet-port-link-not-connect-on-nexus-6000-chassis/td-p/4192482

I know this for N6K not for N5K but I think it same.

Check cisco reply' there are some port run bpduguard by defualt' that can make port down or errdisable.

The solution is bpdufilter but that too risky' so friend can you get license abd use l3 port ? It more safe.

Thanks

MHM

[MHM Cisco World]

Please friend ask more and more before apply any command effect stp domain.

I will do my best to help you 

So first thing to check if link I share is correct or not is check stp is it blk the port or not.

Thanks

MHM

[Sarah.Hussein]

thanks so mcuh for your support, actually there are no blocked ports as per the below output ,, I will try to install the license but not sure because this is a lab enviornment.

!

SW-NDFC-POC-A(config-if)# sh spanning-tree summary totals
Switch is in rapid-pvst mode
Root bridge for: none
Port Type Default is disable
Edge Port [PortFast] BPDU Guard Default is enabled
Edge Port [PortFast] BPDU Filter Default is disabled
Bridge Assurance is enabled
Loopguard Default is disabled
Pathcost method used is short
STP-Lite is enabled

Name Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
112 vlans 0 0 0 223 223

!

SW-NDFC-POC-A# show spanning-tree interface ethernet 1/31
No spanning tree information available for Ethernet1/31

[MHM Cisco World]

If this lab then I hope we can solve it together 

""No spanning tree information available for Ethernet1/31""

And now you use vlan 112' so this vlan is not add to nexus db

You need to add this vlan via

Vlan 112

Name VLAN112

That it' 

And this time please remove this new vlan from peer-link and PO90 before add vlan to db.

Add IP to vlan SVI and use it as keepalive.

Waiting good news 

MHM