ボンディングリンクがフラップし、スイッチに特別なログが出力される

Issue

• サーバーのボンディングがフラップ (継続的にアップ状態とダウン状態を繰り返す) し、スイッチログに以下のメッセージが出力されます。

Sep 14 13:48:28.714 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 9c8e.991c.xxxx
in vlan 1 is flapping between port Po20 and port Gi0/24
Sep 14 13:48:43.923 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 9c8e.991c.xxxx
in vlan 1 is flapping between port Po20 and port Gi0/24
Sep 14 13:48:59.157 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 9c8e.991c.xxxx
in vlan 1 is flapping between port Po20 and port Gi0/24
Sep 14 13:49:14.374 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 9c8e.991c.xxxx
in vlan 1 is flapping between port Po20 and port Gi0/24
Sep 14 13:49:15.683 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 001c.c4c1.yyyy
in vlan 1 is flapping between port Po20 and port Gi0/44
Sep 14 13:49:29.608 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 9c8e.991c.xxxx
in vlan 1 is flapping between port Gi0/24 and port Po20
Sep 14 13:49:40.991 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 001c.c4c1.yyyy
in vlan 1 is flapping between port Po20 and port Gi0/44
Sep 14 13:49:44.833 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 9c8e.991c.xxxx
in vlan 1 is flapping between port Po20 and port Gi0/24
Sep 14 13:50:00.058 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 9c8e.991c.xxxx
in vlan 1 is flapping between port Po20 and port Gi0/24
Sep 14 13:50:12.843 EDT:%SW_MATM-4-MACFLAP_NOTIF:Host 001c.c4c1.yyyy

• リンクがフラップするのはなぜですか?