Intel 460T - Manual (Page 20)

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C H A P T E R 2 Intel Express 460T Standalone Switch Users Guide
Flow Control
When network traffic is heavy, the switch’s port buffers fill up faster than
the switch can send the information. In cases like this, the switch tells the
transmitting device to wait until the information in the buffer can be sent.
This traffic control mechanism is called flow control.
The method of flow control depends on whether the port is set to full-duplex
or half-duplex. If a port operates at half-duplex, the switch sends a collision
(also called backpressure) which causes the transmitting device to wait. If
the port operates at full-duplex, the switch sends out an IEEE 802.3x PAUSE
frame. You can enable or disable flow control for each port on the 460T
switch.
Spanning Tree Protocol
Spanning Tree is a protocol that prevents loops within the network
topology. A loop can occur if there is more than one path for information to
travel between devices. The Spanning Tree Protocol works by determining
the “cost” of a connection. For example, if two devices are connected by two
links, Spanning Tree uses the connection with the lowest cost and blocks
the second connection.
Spanning Tree prevents loops by allowing only one active path between any
two network devices at a time. However, you can also use this behavior to
establish redundant links between devices that can take over if the primary
link fails.
Path: 3
Cost: 100
Path: 2
Cost: 200
Path: 1
Cost: 100
Switch A Switch C
Server B PC Client A
Switch B
In this example, Client A can communicate with Server B over two different
paths. The primary path is Path 1 because the cost of the connection
between switches A and C is lower than the cost between switches A, B and
C. If the primary path fails, then traffic is automatically sent over the backup
path.
Primary Path from Client A to Server B: Switch A –> Switch C
Backup Path from Client A to Server B:
Switch A –> Switch B –> Switch C