Users Guide

– rx off: enter the keywords rx off to ignore the received flow 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 traffic is received.
– 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.
– negotiate: enable pause-negotiation with the egress port of the peer device. If the negotiate
command is not used, pause-negotiation is disabled.
NOTE: The default is rx off.
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MTU Size
The Aggregator auto-configures interfaces to use a maximum MTU size of 12,000 bytes.
If a packet includes a Layer 2 header, the difference 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 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 592-12000, with a default of 1554.
The table below lists out the various Layer 2 overheads found in Dell Networking OS and the number of
bytes.
Difference between Link MTU and IP MTU
Layer 2 Overhead Difference between Link MTU and IP MTU
Ethernet (untagged) 18 bytes
VLAN Tag 22 bytes
Untagged Packet with VLAN-Stack Header 22 bytes
Tagged Packet with VLAN-Stack Header 26 bytes
Link MTU and IP MTU considerations for port channels and VLANS are as follows.
Port Channels:
• All members must have the same link MTU value and the same IP MTU value.
• The port channel link MTU and IP MTU must be less than or equal to the link MTU and IP MTU values
configured on the channel members.
For example, if the members have a link MTU of 2100 and an IP MTU 2000, the port channel’s MTU
values cannot be higher than 2100 for link MTU or 2000 bytes for IP MTU.
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Interfaces