API Guide

Port Pipes
A port pipe is a Dell Networking-specific term for the hardware packet-processing elements that handle network traffic to and from a set
of front-end I/O ports. The physical, front-end I/O ports are referred to as a port set. The system has 10 switch cards and each card has
only one port pipe and 48 ports in each.
• For ports connected through the port extender, you can have a maximum of 4 sessions system.
• For ports directly attached to the chassis you can have a maximum of 4 sessions per port pipe.
Refer to Port Numbering Convention for the exact port location on switch line cards.
Configure MTU Size on an Interface
Maximum Transmission Unit (MTU) is defined as the entire Ethernet packet (Ethernet header + FCS + payload).
The link MTU is the frame size of a packet, and the IP MTU size is used for IP fragmentation. If the system determines that the IP packet
must be fragmented as it leaves the interface, the system divides the packet into fragments no bigger than the size set in the
ip mtu
command.
NOTE: Because different networking vendors define MTU differently, check their documentation when planning MTU
sizes across a network.
The following table lists the range for each transmission media.
Transmission
Media
MTU Range (in bytes)
Ethernet
The MTU range is from 594 to 9216, with a default of 1554.
The IP MTU automatically configures.
Using Ethernet Pause Frames for Flow Control
Ethernet Pause Frames allow for a temporary stop in data transmission. A situation may arise where a sending device may transmit data
faster than a destination device can accept it. The destination sends a PAUSE frame back to the source, stopping the sender’s
transmission for a period of time.
An Ethernet interface starts to send pause frames to a sending device when the transmission rate of ingress traffic exceeds the egress
port speed. The interface stops sending pause frames when the ingress rate falls to less than or equal to egress port speed.
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 destination address equal to this
multicast address.
The PAUSE frame is defined by IEEE 802.3x and uses MAC Control frames to carry the PAUSE commands. Ethernet pause frames are
supported on full duplex only.
If a port is over-subscribed, Ethernet Pause Frame flow control does not ensure no-loss behavior.
Restriction: Ethernet Pause Frame flow control is not supported if PFC is enabled on an interface.
Control how the system responds to and generates 802.3x pause frames on Ethernet interfaces. The default is rx off tx off. INTERFACE
mode. flowcontrol rx [off | on] tx [off | on] monitor session-ID
Where:
rx on: Processes the received flow control frames on this port.
rx off: Ignores the received flow control frames on this port.
tx on: Sends control frames from this port to the connected device when a higher rate of traffic is received.
tx off: Flow control frames are not sent from this port to the connected device when a higher rate of traffic is received.
monitor session-ID: Enables mirror flow control frames on this port.
Changes in the flow-control values may not be reflected automatically in show interface output. To display the change, apply the new
flow-control setting, perform a
shutdown followed by a no shutdown on the interface, and then check re-display the show interface
output for the port.
422
Interfaces