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A mass of TC packets in the network causes the S2300 switch detaching with the network irregularly

Publication Date:  2019-07-24 Views:  128 Downloads:  0

Issue Description

Networking mode:
DMS network management----S9306-1-----S2300
                                                 |     STP  |
The S2300 double upstream to two S9306 devices, and start the STP protocol in the middle, the S2300 network management address is in the S9306-1, the DMS network management and the S2300 device are connected through the Layer 3.
The symptom of the problem:
In the DMS network management, the S2300 network element detaches irregularly, and it can restore automatically several minutes later.

Alarm Information


Handling Process

1. Check the process of the network management software is normal, and there isn’t any abnormal status, and the S9306 device network element in the network management is normal, and the network element hasn’t detached, hence, exclude the network management software’s problem.
2. Check the S2300 switch, and all is normal, all the S2300 devices have the phenomena of network element detaching in the network management, so exclude the S2300’s problem.
3. Because the S9306 is normal, so the link from the DMS network management to the S9306 is normal, and the Layer 2 services from the S2300 to the S9306 are all normal, so exclude the link’s problem.
4. While the network element detaching, in the network management, ping 2300 management address, we can’t ping through. In the S9306 device, view the S2300 management address’s ARP, but the ARP isn’t exist, so the problem may be caused by the ARP has discarded. Statisc analysis in the S9306-1, we find there are lots of TC packets sending up from the S9306-1 to the CPU, after the S9306 receiving the TC packet, it will clear off the ARP entry, and refresh the ARP again. As the S9306-1 is the Layer 3 gateway, there are thousands of ARP, and a part of the ARPs can’t be learnt while refreshing the ARP, then causes the management address of the S2300 switch can’t be ping through at a moment. TC BPDU is producing while the STP switch monitoring the network topology is changing, and the link hasn’t interrupted, there won’t produce the TC packet. View the S2300 device, we find the downstream ports of the S2300 are all in the STP, these ports connect with the users directly. After the users shut down the machines, the S2300 device will produce a TC packet. Finally, modify all the downstream ports of the S2300 as to the boundary ports, and the problem doesn’t happen again, then the problem has been settled out.

Root Cause

1. The network management software has problem;
2. The S2300 switch has problem;
3. Network packet loss;