Users Guide

Dell PowerConnect 55xx Systems User Guide 17
Virtual Cable Testing (VCT)
VCT detects and reports copper link cabling faults, such as open cables and
cable shorts.
For more information, see "Diagnostics" on page 248.
Auto-Negotiation
Auto-negotiation enables the device to advertise modes of operation. The
auto-negotiation function enables an exchange of information between two
devices that share a point-to-point link segment, and automatically
configures both devices to take maximum advantage of their transmission
capabilities.
The PowerConnect 5500 series enhances auto-negotiation by providing port
advertisement. Port advertisement enables the system administrator to
configure the port speeds that are advertised.
For more information, see "Port Configuration" on page 397 or "LAG
Configuration" on page 403.
MDI/MDIX Support
Standard wiring for end stations is known as Media-Dependent Interface
(MDI), and standard wiring for hubs and switches is known as Media-
Dependent Interface with Crossover (MDIX).
If auto-negotiation is enabled, the device automatically detects whether the
cable connected to an RJ-45 port is MDIX (crossed) or MDI (straight). This
enables both types to be used interchangeably.
If auto-negotiation is not enabled, only MDI (straight) cables can be used.
For more information, see "Port Configuration" on page 397 or "LAG
Configuration" on page 403.
MAC Address Supported Features
MAC Address Capacity Support
The device supports up to 16K MAC addresses and it reserves specific MAC
addresses for system use.