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The NDP protocol packets on S switch lead to Cisco switch report MAC-flapping (00e0.fc09.bcf9)

Publication Date:  2018-03-31 Views:  93 Downloads:  0
Issue Description

The Cisco switch connect to two Huawei S5720, the topology like below:

Gi1/0/6 connect to huawei S5720 Switch 

Po 30 connect to huawei S5720 switch configure with istack

Po31 connect to huawei S5720 Switch configure with istack

Customer found that the cisco switch has mac-flapping on those three ports.
 

Alarm Information

Mar 20 23:44:57: %SW_MATM-4-MACFLAP_NOTIF: Host 00e0.fc09.bcf9 in vlan 1 is flapping between port Po30 and port Gi1/0/6

Mar 21 00:20:01: %SW_MATM-4-MACFLAP_NOTIF: Host 00e0.fc09.bcf9 in vlan 1 is flapping between portGi1/0/6 and port Po30

Mar 21 00:21:01: %SW_MATM-4-MACFLAP_NOTIF: Host 00e0.fc09.bcf9 in vlan 1 is flapping between port Gi1/0/6 and port Po30

Mar 21 00:22:01: %SW_MATM-4-MACFLAP_NOTIF: Host 00e0.fc09.bcf9 in vlan 1 is flapping between port Gi1/0/6 and port Po30

Mar 21 00:57:05: %SW_MATM-4-MACFLAP_NOTIF: Host 00e0.fc09.bcf9 in vlan 1 is flapping between port Po30 and portPo31

Mar 21 00:58:06: %SW_MATM-4-MACFLAP_NOTIF: Host 00e0.fc09.bcf9 in vlan 1 is flapping between port Po30 and port Po31

Handling Process

1. check the mac address table on cisco, there are only three ports that connect to Huawei switches have mac flapping;

2. in the LAB test this scenario, we found that the NDP protocol use 00E0-FC09-BCF9 as the source of the protocol message mac;

3. and then we undo ndp enable on Huawei switches, we did not receive packets that the source mac address is 00E0-FC09-BCF9.

Root Cause

None

Solution

disable  NDP protocol on all the Huawei switches that connect to Cisco switch

system-view

undo ndp enable

Suggestions

Huawei Self-Research switch only NDP will use 00E0-FC09-BCF9 as the source of the protocol message mac, and NDP is the default enabling, so in this scenario will lead to the mac-address flapping on cisco switch. The mac address flapping normally has no effect on the business. 

On the same local area network, multiple Huawei switches are connected to the cisco switch, and Huawei switches is L2. Because the cisco switch will learn the MAC ,the mac flapping alarm is reported incorrectly. Therefore, it is recommended that you shut down the NDP on Huawei Switch.

END