Transmission self-loop leads to the failure case of 2826 Switch unable to network management

August 2012, the current network use of a 2826 switch can not remote Telnet logon situation, ping switch network management IP address serious packet loss. The process is probably as follows:

1, the site through the console port login switch to confirm the normal equipment configuration.

2, the use of test terminals to configure IP address, connected to the switch network management port, Ping switch does not pass; Test terminal configuration Switch IP address to connect to the network, can ping through the network management, to ensure that there is no problem with the switch management port

3, replace the switch network management port, found that the phenomenon of failure still exists, suspected switch machine has problems

4, the switch for the whole machine replacement, the replacement found that the phenomenon still exists, to confirm the failure of equipment caused

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5, on-site personnel on the health of the switch check, found that the high load of the switch, further inspection, found that the switch has a port loop, resulting in high equipment load. (The loop here is not a chain Lu Cheng between switches, instead, the port of the switch is connected to the transmission SDH equipment, the port that transmits the SDH device has the self loop, and if the broadcast packet enters the port, it will be forwarded back again, so that the other ports will receive the broadcast packet two times, and the two broadcast packets corresponding to the source port are different, Will cause the VLAN communication to fail)

6, through shutdown the port, the switch back to normal.

Summary: In this fault processing, the processing personnel did not first check the operation load of the equipment, and according to experience to suspect equipment, port hardware failure, delay the processing of the fault.