Involved Products and Versions
All products and versions
Networking
As shown in Figure 1-1, terminals are connected to SwitchC and SwitchD, and Switch C is connected to the Internet through SwitchA and SwitchB in the upstream direction. MSTP is deployed on the network to remove loops. VRRP is configured on both SwitchA and SwitchB to implement reliability and load balancing.
Figure 1-1 Networking diagram of two master devices in a VRRP group in VRRP+MSTP networking
Fault Symptom
Both SwitchA and SwitchB are VRRP master devices, and some network segments cannot access the Internet in wireless and wired services.
Cause Analysis
A loop occurs on SwitchD.
Troubleshooting Procedure
Step 1 Run the display cpu-defend statistics all command. It is found that a large number of VRRP packets are sent to the CPU while a large number of VRRP packets are discarded.
<HUAWEI> display cpu-defend
statistics all
Statistics on slot 2:
--------------------------------------------------------------------------------
Packet Type
Pass(Packet/Byte) Drop(Packet/Byte)
Last-dropping-time
--------------------------------------------------------------------------------
vrrp
47876567 1856471019
2017-06-21 10:46
3255606556
126240029k
Step 2 Run the display trapbuffer command to check alarm information on the switch. An alarm indicating MAC address flapping is generated.
#Jun 21 2017 10:36:14 HX-1 L2IFPPI/4/MFLPVLANALARM:OID 1.3.6.1.4.1.2011.5.25.160.3.7 MAC move detected, VLANID = 28, MacAddress = 12b7-c3d0-9070, Original-Port = XGE2/0/0, Flapping port = XGE2/0/10 and XGE2/0/6. Please check the network accessed to flapping port.
Check that a loop occurs on SwitchD based on Original-Port and Flapping port in the alarm information. After the loop is removed, the fault is rectified.
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