Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 501
Con the MTU Size on an Interface, Untagged Packet with VLAN-Stack Header
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The flow control sender and receiver must be on the same port-pipe. Flow control is not supported across different 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 { }] - rx on: enter the keywords rx on to process the received flow control frames on this port. - 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. - 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 594 to 12000, with a default of 1554 IP MTU automatically configures. The following table lists the various Layer 2 overheads in the Dell Networking OS and the number of bytes. Table 37. Layer 2 Overhead Layer 2 Overhead Ethernet (untagged) VLAN Tag Untagged Packet with VLAN-Stack Header Tagged Packet with VLAN-Stack Header Difference Between Link MTU and IP MTU 18 bytes 22 bytes 22 bytes 26 bytes Link MTU and IP MTU considerations for port channels and VLANs are as follows. Port Channels: Interfaces 501
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