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hutcha4113
Beginner

Host flapping between PO Channels (Etherchannel)

I have read some of the other posts, but cannot seem to find the reason for some Windows Hosts flapping on Port Channel.

 

We have a brand new Cisco Switch (WS-C3650-48PS) running Cat3K_caa_universalk9 03.06.06.E.  The We have a few Windows Hosts plugged in - all of which are Windows 2012 R2.

 

NIC Teaming is enabled on the Windows Hosts, and is set to LACP/Dynamic.

 

Example of a Port Channel setup:

interface Port-channel110
 switchport access vlan 10
 switchport mode access
 lacp max-bundle 2

 

The switch ports assigned to this port channel:

interface GigabitEthernet1/0/7
 switchport access vlan 10
 switchport mode access
 channel-protocol lacp
 channel-group 110 mode active
 spanning-tree portfast
 spanning-tree bpdufilter enable
!
interface GigabitEthernet1/0/8
 switchport access vlan 10
 switchport mode access
 channel-protocol lacp
 channel-group 110 mode active
 spanning-tree portfast
 spanning-tree bpdufilter enable

 

The Host MAC address for the Teamed Adapters, will regularly (at least once a week) generate a flapping error to our Network Monitoring Software.  The Host will flap between Port Channel 1, and the Channel above.

 

Port Channel 1 is the connection from this Switch to the Core Switch (3750).  Here is the configuration of the ports in this Channel:

interface GigabitEthernet1/0/1
 description ***Server Backbone - to Core - Trunk***
 switchport trunk allowed vlan 10
 switchport mode trunk
 switchport nonegotiate
 channel-group 1 mode on
!
interface GigabitEthernet1/0/2
 description ***Server Backbone - to Core - Trunk***
 switchport trunk allowed vlan 10
 switchport mode trunk
 switchport nonegotiate
 channel-group 1 mode on

 

I can verify that the Host in question (and in fact all hosts on this switch) are only plugged into this switch for VLAN 10 Access.  


We are also having issues with this particular Switch - it will stop responding to its VLAN 10 IP Address (monitoring software will lose connectivity) - it has also rebooted itself a couple of times, so we may also be dealing with a Hardware issue.


At any rate, I would like to clear the flapping issue first, to see if it resolves some of the other things we are seeing.

 

2 REPLIES 2
Reza Sharifi
Hall of Fame Expert

We are also having issues with this particular Switch - it will stop responding to its VLAN 10 IP Address (monitoring software will lose connectivity) - it has also rebooted itself a couple of times, so we may also be dealing with a Hardware issue.

Since you have all these issues with a new switch, RMA back to Cisco and get a replacement.

HTH

Austin Sabio
Enthusiast

I would suggest to check logs for errors also check if you are hitting bug# CSCuz52041. Best way to troubleshoot to downgrade your code to a stable version-to isolate the issue- then upgrade to proper code. 

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCuz52041/?referring_site=bugquickviewredir

less likely could be 

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvb24904/?referring_site=bugquickviewredir

I hope this helps. Good luck!