Administrator Guide
• Flow-control discard threshold in KB: from 1-2013 (default= 75KB)
The pause is started when either the packet pointer or the buer threshold is met (whichever is met rst). When the discard threshold is
met, packets are dropped.
The pause ends when both the packet pointer and the buer threshold fall below 50% of the threshold settings.
The discard threshold denes when the interface starts dropping the packet on the interface. This may be necessary when a connected
device doesn’t honor the ow control frame sent by the switch.
The discard threshold should be larger than the buer threshold so that the buer holds at least hold at least three packets.
Enabling Pause Frames
Enable Ethernet pause frames ow control on all ports on a chassis or a line card. If not, the system may exhibit unpredictable behavior.
NOTE: Changes in the ow-control values may not be reected automatically in the show interface output. As a workaround,
apply the new settings, execute shut then no shut on the interface, and then check the running–cong of the port.
NOTE: If you disable rx flow control, Dell Networking recommends rebooting the system.
The ow control sender and receiver must be on the same port-pipe. Flow control is not supported across dierent port-pipes.
To enable pause frames, use the following command.
• Control how the system responds to and generates 802.3x pause frames on 10 Gigabit line cards.
INTERFACE mode
flowcontrol rx [off | on] tx [off | on] [threshold {<1-2047> <1-2013> <1-2013>}] monitor
session-ID
• rx on: enter the keywords rx on to process the received ow control frames on this port.
• rx off: enter the keywords rx off to ignore the received ow control frames on this port.
• tx on: enter the keywords tx on to send control frames from this port to the connected device when a higher rate of trac is
received.
• tx off: enter the keywords tx off so that ow control frames are not sent from this port to the connected device when a
higher rate of trac is received.
• threshold: when you congure tx on, you can set the threshold values for:
• Number of ow-control packet pointers: the range is from 1 to 2047 (default = 75).
• Flow-control buer threshold in KB: the range is from 1 to 2013 (default = 49KB).
• Flow-control discard threshold in KB: the range is from 1 to 2013 (default= 75KB)
• monitor session-ID: Enter the keyword monitor then the session–ID to enable mirror ow control frames on the port. The
session–ID range is from 1 to 65535.
Pause control is triggered when either the ow control buer threshold or ow control packet pointer threshold is reached.
Congure the MTU Size on an Interface
If a packet includes a Layer 2 header, the dierence in bytes between the link MTU and IP MTU must be enough to include the Layer 2
header.
For example, for VLAN packets, if the IP MTU is 1400, the Link MTU must be no less than 1422:
1400-byte IP MTU + 22-byte VLAN Tag = 1422-byte link MTU
The MTU range is from 594 to 9216, with a default of 1554 IP MTU automatically congures.
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Interfaces