3750 Switchport flapping

[dapo dimeji]

Hope to get some help on this: 

I have a dell poweredge R720 Server with a broadcom NIC, It's a Virtual Host running 3 diff VM's on it. The server has 4 Adapter connections to two diff Cisco 3750 Switches which have flapping ports. The Switchports are all configured on same Vlan and are access ports. The Broadcom Adapter is configured as a team ( Smart Load Balancing (TM) and Failover ) so the Adapter is load balancing traffic however the Switchport on the other side keeps getting packets from diff MAC Address, which I presume is causing the flapping. Spanning tree is configured on the ports and Etherchannel is not set up to bundle these ports.

Any idea on how to resolve this issues, as I am having failed backup from backup selection  accessing data from these server. 

08: %SW_MATM-4-MACFLAP_NOTIF: Host 90b1.1c55.be92 in vlan 7 is flapping between port Gi5/0/7 and port Gi4/0/3
2394115: Mar 31 11:11:08: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c0a in vlan 7 is flapping between port Gi5/0/15 and port Gi4/0/12
2394116: Mar 31 11:11:10: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c10 in vlan 7 is flapping between port Gi4/0/3 and port Gi4/0/12
2394117: Mar 31 11:11:23: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c03 in vlan 7 is flapping between port Gi5/0/7 and port Gi5/0/15
2394118: Mar 31 11:11:24: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c0a in vlan 7 is flapping between port Gi4/0/12 and port Gi4/0/3
2394119: Mar 31 11:11:24: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c10 in vlan 7 is flapping between port Gi4/0/3 and port Gi4/0/12
2394120: Mar 31 11:11:27: %SW_MATM-4-MACFLAP_NOTIF: Host 90b1.1c55.be92 in vlan 7 is flapping between port Gi5/0/7 and port Gi4/0/3
2394121: Mar 31 11:11:38: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c03 in vlan 7 is flapping between port Gi5/0/15 and port Gi4/0/3
2394122: Mar 31 11:11:38: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c0a in vlan 7 is flapping between port Gi4/0/12 and port Gi4/0/3
2394123: Mar 31 11:11:39: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c10 in vlan 7 is flapping between port Gi5/0/15 and port Gi4/0/3
2394124: Mar 31 11:11:41: %SW_MATM-4-MACFLAP_NOTIF: Host 90b1.1c55.be92 in vlan 7 is flapping between port Gi5/0/7 and port Gi4/0/3
2394125: Mar 31 11:11:53: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c03 in vlan 7 is flapping between port Gi5/0/7 and port Gi5/0/15
2394126: Mar 31 11:11:53: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c0a in vlan 7 is flapping between port Gi5/0/7 and port Gi4/0/12
2394127: Mar 31 11:11:54: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c10 in vlan 7 is flapping between port Gi4/0/3 and port Gi5/0/15
2394128: Mar 31 11:11:57: %SW_MATM-4-MACFLAP_NOTIF: Host 90b1.1c55.be92 in vlan 7 is flapping between port Gi4/0/12 and port Gi5/0/7
2394129: Mar 31 11:12:08: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c03 in vlan 7 is flapping between port Gi4/0/3 and port Gi4/0/12
2394130: Mar 31 11:12:08: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c0a in vlan 7 is flapping between port Gi5/0/15 and port Gi4/0/12
2394131: Mar 31 11:12:09: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c10 in vlan 7 is flapping between port Gi5/0/7 

[eduardopozo56]

I dont know if i got your set up properly but seems like you have the links bundled on the server side (Broadcom Adaptor) and not on the switch side, and you are also splitting the ports in two different switches.

If you are going to use a bundling mechanism on the server side, you have to also bundle on the Switch side and connect all the ports on the same switch.
Note: If you had Nexus, you could use VPC to split the ports in different switches.

The ports are not flapping, its just seeing the mac jumping from one port to another, as the Server is load balancing packets through all the links.

[dapo dimeji]

Thanks for your reply.

I have connected all the ports to be on same switch. If I Bundle the ports on the switch side, would you presume this should resolve the flapping showing on the switch ports? Or regardless whatever will be done since the   MAC Addresses are jumping the switch will still flag this up?

See current switch ports:

:15:37: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c10 in vlan 7 is flapping between port Gi4/0/16 and port Gi4/0/12
2395177: Mar 31 12:15:38: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c0a in vlan 7 is flapping between port Gi4/0/12 and port Gi4/0/16
2395178: Mar 31 12:15:52: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c03 in vlan 7 is flapping between port Gi4/0/15 and port Gi4/0/12
2395179: Mar 31 12:15:53: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c0a in vlan 7 is flapping between port Gi4/0/16 and port Gi4/0/3
2395180: Mar 31 12:15:54: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c10 in vlan 7 is flapping between port Gi4/0/15 and port Gi4/0/3
2395181: Mar 31 12:15:56: %SW_MATM-4-MACFLAP_NOTIF: Host 90b1.1c55.be92 in vlan 7 is flapping between port Gi4/0/12 and port Gi4/0/15
2395182: Mar 31 12:16:07: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c03 in vlan 7 is flapping between port Gi4/0/16 and port Gi4/0/12
2395183: Mar 31 12:16:07: %SW_MATM-4-MACFLAP_NOTIF: Host 90b1.1c55.be92 in vlan 7 is flapping between port Gi4/0/15 and port Gi4/0/16
2395184: Mar 31 12:16:08: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c0a in vlan 7 is flapping between port Gi4/0/12 and port Gi4/0/15
2395185: Mar 31 12:16:08: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c10 in vlan 7 is flapping between port Gi4/0/16 and port Gi4/0/12
2395186: Mar 31 12:16:22: %SW_MATM-4-MACFLAP_NOTIF: Host 0015.5d1e.1c03 in vlan 7 is flapping between port Gi4/0/15 and port Gi4/0/16

[eduardopozo56 · Accepted solution]

Hi,

If the links are bundled on the server side then YES, they also need to be bundled on the switch side, that would "fix" the mac flapping issue, as the mac-address would be part of the port-channel and not a single interface.