MAC Flapping between ports

Issue Description:

 客服端无法访问特定的Server;

Root Casuse Analysis:

Found blow logs in distribution layer Cisco 2960G：

*Mar  5 10:31:38: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.1800.0000 in vlan 192 is f
lapping between port Gi0/22 and port Gi0/21
*Mar  5 11:03:45: %SW_MATM-4-MACFLAP_NOTIF: Host 0010.1800.0000 in vlan 192 is f
lapping between port Gi0/22 and port Gi0/21

Action & Validation:

从日志中看出在vlan 192的G0/22和G0/21端口下同时出现了相同的mac address 0010.1800.0000，

查看Server Mac正好为0010.1800.0000，连接在G0/22上游，shutdown G0/21后其他接口访问Server

恢复正常，从G0/21端口下游交换机找到了相同mac的pc。

Lessons Learned and Action Plan:

通过了解造成mac address flapping还存在以下情况：

环路

双网卡server桥接后同时连接到switch上

有的H3C开启STP Swtich与Cisco开启默认Pvst连接，原因H3C交换机的BPDU报文采用固定MAC

00E0-FC09-BCF9或者 000F-E207-F2E0，在CISCO Switch上通过查看spanning protocol

Spanning tree enabled protocol ieee
  Root ID    Priority    4896
             Address     001f.27dd.6200
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    4896   (priority 4096 sys-id-ext 800)
             Address     001f.27dd.6200
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300
Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/0/2          Desg FWD 4         128.2    P2p
Gi1/0/12         Desg FWD 19      128.12   P2p
Gi1/0/22         Desg FWD 19      128.22   P2p

可以通过port-mac命令更改源MAC解决