Dell PowerEdge VRTX - Manual (Page 250)

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FILE LOCATION: C:\Users\gina\Desktop\Checkout_new\Dell Plasma\User
Guide\Plasma_UGSwitching_Ports.fm
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Auto-Negotiation
Auto-negotiation enables automatic detection of speed, duplex mode and
flow control on all switching 10/100/1000BaseT ports. Auto-negotiation is
enabled on all ports by default.
Auto-negotiation is a mechanism established between two link partners to
enable a port to advertise its transmission rate, duplex mode and flow control
abilities to its partner. Both ports then operate at the highest common
denominator.
If connecting a Network Interface Card (NIC) that does not support auto-
negotiation or is not set to auto-negotiation, both the device switching port
and the NIC must be manually set to the same speed and duplex mode.
If the station, on the other side of the link, attempts to auto-negotiate with a
device 100BaseT port that is configured to full duplex, the auto-negotiation
results in the station attempting to operate in half duplex.
MDI/MDIX
The device supports auto-detection of straight-through and crossed cables on
all 10/100/1000BaseT ports. This feature is part of auto-negotiation and is
enabled when Auto-negotiation is enabled.
When the MDI/MDIX (Media Dependent Interface with Crossover) is
enabled, the automatic correction of errors in cable selection is possible, thus
making the distinction between a straight-through cable and a crossover cable
irrelevant. The standard wiring for end stations is known as MDI (Media
Dependent Interface), and the standard wiring for hubs and switches is known
as MDIX.
Flow Control
The device supports 802.3x flow control for ports configured to Full Duplex
mode. By default, this feature is enabled on all ports, and it can be disabled
per port.
Flow control creates a lossless link with no packet loss. The flow control
mechanism enables the receiving side to signal to the transmitting side that
transmission must temporarily be halted to prevent buffer overflow. This
signaling is done by sending PAUSE frames. The ports that receives pause
frames stops transmitting traffic.