Administrator Guide

76 Switch Feature Overview
Switching Features
Flow Control Support (IEEE 802.3x)
Flow control enables lower speed switches to communicate with higher speed
switches by requesting that the higher speed switch refrain from sending
packets for a limited period of time. Transmissions are temporarily halted to
prevent buffer overflows.
For information about configuring flow control, see "Port-Based Traffic
Control " on page 849.
Head of Line Blocking Prevention
Head of Line (HOL) blocking prevention prevents traffic delays and frame
loss caused by traffic competing for the same egress port resources. HOL
blocking queues packets, and the packets at the head of the queue are
forwarded before packets at the end of the queue.
Alternate Store and Forward (ASF)
The Alternate Store and Forward (ASF) feature reduces latency for large
packets. When ASF is enabled, the memory management unit (MMU) can
forward a packet to the egress port before it has been entirely received on the
Cell Buffer Pool (CBP) memory.
AFS, which is also known as cut-through mode, is configurable through the
command-line interface. For information about how to configure the AFS
feature, see the
CLI Reference Guide available at www.dell.com/support.
Jumbo Frames Support
Jumbo frames enable transporting data in fewer frames to ensure less
overhead, lower processing time, and fewer interrupts.
For information about configuring the switch MTU, see "Port Characteristics "
on page 591.
NOTE: This feature is available on the Dell Networking N4000 Series switches
only.