66 Switch FeaturesProtected Ports (Private VLAN Edge)Private VLAN Edge (PVE) ports are a Layer 2 security feature that providesport-based security between ports that are members of the same VLAN. It isan extension of the common VLAN. Traffic from protected ports is sent onlyto the uplink ports and cannot be sent to other ports within the VLAN.For information about configuring IPSG, see "Configuring Port-Based TrafficControl" on page 687.Switching FeaturesFlow Control Support (IEEE 802.3x)Flow control enables lower speed switches to communicate with higher speedswitches by requesting that the higher speed switch refrains from sendingpackets. Transmissions are temporarily halted to prevent buffer overflows.For information about configuring flow control, see "Configuring Port-BasedTraffic Control" on page 687.Head of Line Blocking PreventionHead of Line (HOL) blocking prevention prevents traffic delays and frameloss caused by traffic competing for the same egress port resources. HOLblocking queues packets, and the packets at the head of the queue areforwarded before packets at the end of the queue.Alternate Store and Forward (ASF)The Alternate Store and Forward (ASF) feature reduces latency for largepackets. When ASF is enabled, the memory management unit (MMU) canforward a packet to the egress port before it has been entirely received on theCell Buffer Pool (CBP) memory.AFS, which is also known as cut-through mode, is configurable through thecommand-line interface. For information about how to configure the AFSfeature, see theCLI Reference Guide available at support.dell.com/manuals.
