3com 5500-ei pwr Installation Instruction

 

1-7 

 

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external: Performs external loop test. In the external loop test, self-loop headers  must be used on 

the port of the switch ( for 100M port, the self-loop headers are made from four cores of the 8-core 

cables, for 1000M port, the self-loop header are made from eight cores of the 8-core cables, then 

the packets forwarded by the port will be received by itself.). The external loop test can locate the 

hardware failures on the port.   

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internal: Performs internal loop test. In the internal loop test, self loop is established in the 

switching chip to locate the chip failure which is related to the port.  

 

Note that: 

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After you use the shutdown command on a port, the port cannot run loopback test.  

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You cannot use the speed, duplex, mdi and shutdown commands on the ports running loopback 

test.  

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Some ports do not support loopback test, and corresponding prompts will be given when you 

perform loopback test on them. 

You can enable the system to test the cable connected to a specific port. The test result will be returned 

in five seconds. The system can test these attributes of the cable: Receive and transmit directions (RX 

and TX), short circuit/open circuit or not, the length of the faulty cable.  

Follow these steps to enable the system to test connected cables: 

Enter system view  

— 

Enter Ethernet port view  

interface interface-type 
interface-number 

— 

Enable the system to test 
connected cables  

Required 

 

By performing the following configuration, you can set the interval to perform statistical analysis on the 

traffic of a port. 

When you use the display interface interface-type interface-number command to display the 

information of a port, the system performs statistical analysis on the traffic flow passing through the port 

during the specified interval and displays the average rates in the interval. For example, if you set this 

interval to 100 seconds, the displayed information is as follows: 

 Last 100 seconds input:  0 packets/sec 0 bytes/sec 

 Last 100 seconds output:  0 packets/sec 0 bytes/sec 

Follow these steps to set the interval to perform statistical analysis on port traffic: