Port Flapping Issue on 2960 stacking switch

[Cheen Yaw Loh]

Hi,

I got two Cisco 2960-S - 24 Ports L2 switches (switch1 and 2) stacking together with cisco Stackwise cable. I got servers and each server has 4 ports. two ports teaming together and connect to VLAN71 (one port connect to switch1, another port connect to switch2). Same for the other two ports, just that they are connected to VLAN72. And the teaming setting of the ports is ALB

• Adaptive      Load Balancing (ALB)
  Offers increased network bandwidth by allowing transmission over 2-8 ports      to multiple destination addresses, and incorporates Adapter Fault      Tolerance. Only the primary adapter receives incoming traffic.      Broadcasts/multicasts and non-routed protocols are only transmitted via      the primary adapter in the team. The ANS software load balances      transmissions, based on Destination Address, and can be used with any      switch. Simultaneous transmission only occurs at multiple addresses. This      mode can be connected to any switch.

But I got the flapping warning from the switch, any idea it's the switch issue or server issue? Or the configuration issue?

Gi1/0/13 and port Gi2/0/13

Sep 23 04:05:10.746: %SW_MATM-4-MACFLAP_NOTIF: Host 0025.90a3.edb9 in vlan 71 is flapping between port Gi1/0/8 and port Gi2/0/8

Sep 23 04:05:11.202: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.86ba in vlan 72 is flapping between port Gi1/0/17 and port Gi2/0/17

Sep 23 04:05:11.795: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.864e in vlan 72 is flapping between port Gi2/0/14 and port Gi1/0/14

Sep 23 04:05:15.176: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.85a5 in vlan 71 is flapping between port Gi1/0/6 and port Gi2/0/6

Sep 23 04:05:22.632: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.85a4 in vlan 72 is flapping between port Gi1/0/18 and port Gi2/0/18

Sep 23 04:05:25.688: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.86b8 in vlan 72 is flapping between port Gi1/0/15 and port Gi2/0/15

Sep 23 04:05:25.751: %SW_MATM-4-MACFLAP_NOTIF: Host 0025.90a3.edb9 in vlan 71 is flapping between port Gi1/0/8 and port Gi2/0/8

Sep 23 04:05:25.762: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.8646 in vlan 72 is flapping between port Gi2/0/13 and port Gi1/0/13

Sep 23 04:05:26.889: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.86ba in vlan 72 is flapping between port Gi1/0/17 and port Gi2/0/17

Sep 23 04:05:27.455: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.864e in vlan 72 is flapping between port Gi2/0/14 and port Gi1/0/14

Sep 23 04:05:29.710: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.85a4 in vlan 72 is flapping between port Gi1/0/18 and port Gi2/0/18

Sep 23 04:05:32.960: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.85a5 in vlan 71 is flapping between port Gi2/0/6 and port Gi1/0/6

Sep 23 04:05:40.589: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.86b8 in vlan 72 is flapping between port Gi1/0/15 and port Gi2/0/15

Sep 23 04:05:40.620: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.86ba in vlan 72 is flapping between port Gi1/0/17 and port Gi2/0/17

Sep 23 04:05:40.730: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.8646 in vlan 72 is flapping between port Gi2/0/13 and port Gi1/0/13

Sep 23 04:05:41.055: %SW_MATM-4-MACFLAP_NOTIF: Host 0025.90a3.edb9 in vlan 71 is flapping between port Gi2/0/8 and port Gi1/0/8

Sep 23 04:05:41.973: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.864e in vlan 72 is flapping between port Gi2/0/14 and port Gi1/0/14

[Iker Santamaria Molla]

Hi Cheen,
could you put the topology between the switches and the server? Configuration too.

I believe you have a loop.

Best regards.

[Leo Laohoo]

This is very typical when you connect a client to multiple ports (same switch or multiple switches in the same stack).  This holds true when you don't configure Etherchannel (or the Etherhchannel is misconfigured) on the switch.

[Cheen Yaw Loh]

Thanks guys.

This issue is happened sporadically. I didn't configure etherchannel for the access port but only for trunk port. By right, ALB teaming mode shouldn't need the etherchannel for the switch, right?

I can't provide the whole network topology also, because other switches are not under my control.

[Leo Laohoo]

Where did you get that "ALB" stuff?  It looks like Etherchannel to me.

[Cheen Yaw Loh]

ALB is teaming option for the NIC ports on the servers. it's like Cisco's "Etherchannel".

• Adaptive Load Balancing (ALB)
  Offers increased network bandwidth by allowing transmission over 2-8 ports      to multiple destination addresses, and incorporates Adapter Fault      Tolerance. Only the primary adapter receives incoming traffic.      Broadcasts/multicasts and non-routed protocols are only transmitted via      the primary adapter in the team. The ANS software load balances      transmissions, based on Destination Address, and can be used with any      switch. Simultaneous transmission only occurs at multiple addresses. This      mode can be connected to any switch.

[Leo Laohoo]

So your switchports need to be configured for Etherchannels.

[Cheen Yaw Loh]

No, for all the access ports of the switch, i didn't configure the etherchannel. And from what i know, this ALB doesn't need the switch to be configured as etherchannel.

[Leo Laohoo]

Sep 23 04:05:41.973: %SW_MATM-4-MACFLAP_NOTIF: Host a036.9f12.864e in vlan 72 is flapping between port Gi2/0/14 and port Gi1/0/14

If you do not believe the switch needs to be configured as Etherchannel then these messages (above) are debunking you.

[sbhadrav@cisco.com]

Catalyst 3750 Series Switches in the stack might not boot with the new image after a software upgrade. This issue might be caused because you used archive download-sw /leave-old-sw in the download option.

The /leave-old-sw option keeps the old software version after a download. When you enter reload, only the stack master is reloaded. This fails because the switch as a stack expects all models in the stack to have the same version of the image. As a result, the stack master switch is placed in a disable state, and another member switch is elected as master.

In order to recover from this state, use the archive copy-sw command on the stack master to copy the running image from the Flash memory on one stack member to the Flash memory on one or more other stack members. It copies the software image from an existing stack member to the one with incompatible software. That switch automatically reloads and joins the stack as a fully functioning member.

Refer to the Troubleshoot section of Catalyst 3750 Software Upgrade in a Stack Configuration with Use of the Command-Line Interface for other issues related to Cisco IOS software upgrade in Cisco Catalyst 3750 switches.

Unable to create temp dir "flash:update"
This error message can appear when you upgrade the Cisco IOS software:

Unable to create temp dir "flash:update"
This error messages indicates that the temporary directory "update" already exists in the flash: file system, and the current upgrade process is not able to use the directory. The directory could have been left in the flash: file system as a result of any previous upgrade attempts.

In order to resolve this issue, complete these steps:

Use the rmdir flash:update command in order to delete the temporary directory.

Issue the delete flash:update command.

If the rmdir flash:update command does not work, then issue the delete /force /recursive flash:update command.

Continue with the Cisco IOS software upgrade procedure.