Dell Force10 S55T FTOS Command Line Reference Guide for the S55 System FTOS 8. - Page 452

www.dell.com | support.dell.com tx off threshold (C-Series and S-Series only) Enter the keywords tx off so that flow control frames are not sent from this port to the connected device when a higher rate of traffic is received. When tx on is configured, you can set the threshold values for: Number of flow-control packet pointers: 1-2047 (default = 75) Flow-control buffer threshold in KB: 1-2013 (default = 49KB) Flow-control discard threshold in KB: 1-2013 (default= 75KB) Defaults C-Series: rx off tx off E-Series: rx on tx on S-Series: rx off tx off S55: rx on Command Modes INTERFACE Command History Version 8.3.5.0 Version 8.1.1.0 Version 6.5.1.9 and 7.4.1.0 Version 7.8.1.0 Introduced on the S55, rx only. Introduced on E-Series ExaScale Introduced on E-Series Introduced on C-Series and S-Series with thresholds Usage Information The globally assigned 48-bit Multicast address 01-80-C2-00-00-01 is used to send and receive pause frames. To allow full duplex flow control, stations implementing the pause operation instruct the MAC to enable reception of frames with a destination address equal to this multicast address. The pause: • Starts when either the packet pointer or the buffer threshold is met (whichever is met first). When the discard threshold is met, packets are dropped. • Ends when both the packet pointer and the buffer threshold fall below 50% of the threshold settings. The discard threshold defines when the interface starts dropping the packet on the interface. This may be necessary when a connected device does not honor the flow control frame sent by the S-Series. The discard threshold should be larger than the buffer threshold so that the buffer holds at least hold at least 3 packets. Note: The S55 supports only the rx control option. The S55 does not transmit pause frames. Important Points to Remember • Do not enable tx pause when buffer carving is enabled. Consult Dell Force10 TAC for information and assistance. • Asymmetric flow control (rx on tx off or rx off tx on) setting for the interface port less than 100 Mb/s speed is not permitted. The following error is returned: Can't configure Asymmetric flowcontrol when speed