User manual
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Deferred
Number of successful output frames
（
the receiver is busy, but
It sends successfully after a delay
）
OutFiltered
Filtered frames output
OutDiscards
Discarded frames output
（
because of cache, flow control, etc.
）
5.11 Network Diagnosis
5.11.1 Port mirroring
Port mirroring refers to copy data from the port which need to be monitored to appointed monitoring port for
analysis and monitoring. Ethernet switch supports many-for-one mirror which means messages from several
ports can be copied to a monitored port. User can appoint the direction of monitored message, such as only
monitoring of transmitted messages of appointed port. The device configures port mirroring function through
port mirroring group. Each group includes a monitored port and a group of mirror ports. Total bandwidth of
mirroring is not more than that of monitored port. It is good to monitor and manage its internal network data
when using port mirroring in a company. It is also good to locate the failure when network is cut up.
（
Figure 5.11.1
）
Example as figure: Port 4 collects all of the data from port 4 and port 5
（
Figure 5.11.2
）
1. This function is not often used. Otherwise other port-based higher management function like RSTP,IGMP SNOOPING
2. Port mirroring function can only deal with the normal FCS packets. It cannot deal with error data frames.