18 Introduction
•PDAs
• Audio and video remote monitoring
For more information about Power over Ethernet, see "Managing Power over Ethernet".
Head of Line Blocking Prevention
Head of Line (HOL) blocking results in traffic delays and frame loss caused by traffic competing for the
same egress port resources. To prevent HOL blocking the device queues packets, and the packets at the
head of the queue are forwarded before packets at the end of the queue.
Flow Control Support (IEEE 802.3X)
Flow control enables lower speed devices to communicate with higher speed devices, by requesting that
the higher speed device refrains from sending packets. Transmissions are temporarily halted to prevent
buffer overflows.
For information on configuring Flow Control for ports or LAGs, see "Defining Port Configuration" or
"Defining LAG Parameters."
Back Pressure Support
On half-duplex links, the receiving port prevents buffer overflows by occupying the link so that it is
unavailable for additional traffic.
For information on configuring Flow Control for ports or LAGs, see "Defining Port Configuration" or
"Defining LAG Parameters."
Virtual Cable Testing (VCT)
VCT detects and reports copper link cabling occurrences such as open cables and cable shorts. For more
information on testing cables, see "Running Cable Diagnostics".
MDI/MDIX Support
The device automatically detects whether the cable connected to an RJ-45 port is crossed or straight
through, when auto-negotiation is enabled.
Standard wiring for end stations is Media-Dependent Interface (MDI) and the standard wiring for hubs
and switches is known as Media-Dependent Interface with Crossover (MDIX).
For information on configuring MDI/MDIX for ports or LAGs, see "Defining Port Configuration" or
"Defining LAG Parameters."
Auto Negotiation
Auto negotiation allows the device to advertise modes of operation. The auto negotiation function
provides the means to exchange information between two devices that share a point-to-point link
segment, and to automatically configure both devices to take maximum advantage of their
transmissioncapabilities.