Command Line Reference Guide

452 | Interfaces
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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
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.
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 <1G, config
ignored
tx off 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.
threshold
(C-Series and
S-Series only
)
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)
Version 8.3.5.0
Introduced on the S55,
rx only.
Version 8.1.1.0 Introduced on E-Series ExaScale
Version 6.5.1.9 and 7.4.1.0 Introduced on E-Series
Version 7.8.1.0 Introduced on C-Series and S-Series with thresholds
Note: The S55 supports only the rx control option. The S55 does not transmit pause
frames.