Flow Control ScenarioBCM5718 Programmer’s Guide
Broadcom®
January 29, 2016 • 5718-PG108-R Page 575
– Either half/full-duplex connection at Gigabit speed (i.e., this scenario will cover two subcases).
File Transfer
The client begins a FTP session (see Figure 56). The file size is very large and will take several minutes for a
complete transfer, even at Gigabit wire speed.
Figure 56: File Transfer Scenario: FTP Session Begins
Speed Mismatch
The Client sends pause frame(s) to the switch (see Figure 57). The Client’s pipe has been saturated, and the
RX buffers are almost exhausted. The Client begins sending pause frames, when the RX buffer high-water
mark/threshold is hit. Any number of reasons can account for the RX buffer issue. The assumption will be made
that the Client PCI bus lack bandwidth to DMA packets, at wire speed, to host memory. The user may be playing
a DVD, for example.
Figure 57: File Transfer Scenario: Speed Mismatch
Gigabit Server
Switch
Gigabit Client
File Transfer
File
Gigabit Server
Switch
Gigabit Client
Pause packets
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