Filter
Top Products
– 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.
– threshold: when you configure tx on, you can set the threshold values for:
* Number of flow-control packet pointers: the range is from 1 to 2047 (default = 75).
* Flow-control buffer 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)
Pause control is triggered when either the flow control buffer threshold or flow control packet pointer
threshold is reached.
Configure the MTU Size on an Interface
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 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 592 to 9216, with a default of 9216. IP MTU automatically configures.
The following table lists the various Layer 2 overheads in the Dell Networking OS and the number of
bytes.
Table 26. Layer 2 Overhead
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.
VLANs:
• All members of a VLAN must have the same IP MTU value.
• Members can have different Link MTU values. Tagged members must have a link MTU 4–bytes higher
than untagged members to account for the packet tag.
Interfaces
435