Dell C1048P Port Extender Networking Command-Line Reference Guide for the C900 - Page 930

Version 9.9(0.0) 9.2(1.0) 8.3.19.0 8.3.11.1 8.3.7.0 8.1.1.0 6.5.1.9/7.4.1.0 7.8.1.0 Description Introduced on the C9010. Introduced on the Z9500. Introduced on the S4820T. Introduced on the Z9000. Introduced on the S4810. Introduced on the E-Series ExaScale. Introduced on the E-Series. Introduced on the C-Series and S-Series with the thresholds option. 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 the 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 switch. The discard threshold should be larger than the buffer threshold so that the buffer holds at least hold at least three packets. Changes in the flow-control values may not be reflected automatically in the show interface output. As a workaround, apply the new settings, execute shut then no shut on the interface, then check the running-config of the port using the show interface command. Important Points to Remember • Do not enable tx pause when buffer carving is enabled. For information and assistance, consult Dell Networking TAC. • 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