3.4.4 Notes on using bandwidth monitoring
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(1) Relationship between Bandwidth Monitoring, Transmit Ethernet Interface, and Transmit Queue
In the following cases, compliance frames may be discarded on the transmit Ethernet interface or the transmit queue:
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When the monitoring bandwidth value specified in bandwidth monitoring is set to a value greater than the bandwidth value of the transmit Ethernet interface or transmit queue of the applicable flow
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When a flow that does not use bandwidth monitoring and a flow that uses bandwidth monitoring are sent to the same transmit Ethernet interface or transmit queue
In particular, when using multiple bandwidth monitoring for multiple flows, pay attention to the sum of the monitored bandwidth values for each bandwidth monitoring.
(2) Bandwidth monitoring of protocol control frames
Protocol control frames are also subject to bandwidth monitoring on the Switch. Therefore, because a protocol control frame might also be discarded as a non-compliant frame in maximum bandwidth control, allocate the maximum bandwidth only after reviewing whether the protocol control frames will be sent to the Switch.
(3) Using Maximum Bandwidth Control for TCP Frames
When you use maximum bandwidth control, repeated slow startup of TCP might result in an extremely slow data transfer rate.
To avoid this problem, use minimum bandwidth monitoring to specify an operation that lowers the queuing priority so that frames can be discarded more easily. This setting ensures that frames that exceed the contracted bandwidth will not be discarded immediately, but will be discarded only when the output line is congested.
(4) Simultaneous operation with other functions
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If a frame that matches a filter entry with a discard operation specified (including an implicit discard entry) is received, the frame is discarded but the frame is subject to bandwidth monitoring.
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If a bandwidth monitoring violation and storm detection occur at the same time, more frames may be discarded, including frames that would originally be forwarded.