Broadcom BCM5722 - Figure 68: File Transfer Scenario: FTP Session Begins; Figure 69: File Transfer Scenario: Speed Mismatch

Programmer’s Guide BCM5722
10/15/07
Broadcom Corporation
Document 5722-PG101-R Flow Control Scenario Page 514
FILE TRANSFER
The client begins a FTP session (see Figure 68). The file size is very large and will take several minutes for a complete trans-
fer, even at gigabit wire speed.
Figure 68: File Transfer Scenario: FTP Session Begins
SPEED MISMATCH
The Client sends pause frame(s) to the switch (see Figure 69). 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 num-
ber 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 69: File Transfer Scenario: Speed Mismatch
Gigabit Server
Switch
Gigabit Client
File Transfer
File
Gigabit Server
Switch
Gigabit Client
Pause packets