Increasing Bandwidth by Segmenting 10BASE-T
Collision Domain
The Transition Networks’ pocket switch adapts to the fact that each
Ethernet network device (station) is connected independently to the
shared Ethernet signaling system, called the network medium. Each
station transmits serially over the shared medium to every other
attached station. Access to the medium is determined by a medium
access control (MAC) mechanism in the Ethernet interface of the station.
The Ethernet CSMA/CD Protocol
The Ethernet medium access control mechanism is based on the Carrier
Sense Multiple Access with Collision Detection (CSMA/CD) protocol.
Under the CSMA/CD protocol, each station waits until there is no signal
on the channel (Carrier Sense) and then begins transmitting (Multiple
Access). Since signals take a finite time to travel from one end of an
Ethernet network to the other, the first bits of a transmitted frame do not
reach all parts of the network simultaneously. Two stations could sense
that the network is idle and start transmitting frames simultaneously.
When this happens, the Ethernet system senses the signal "collision",
stops the transmission, and resends the frames (Collision Detection).
Thus, a collision domain is a single CSMA/CD network in which a
collision will occur if two network stations transmit at the same time.
Ethernet Switching
The Transition Networks’ pocket switch can improve network
performance by breaking the large CSMA/CD collision domain into two
separate collision domains (called segments). Network segmentation is
achieved by regulating the number of data signals sent among stations.
Since the first two fields in an Ethernet data packet carry 48-bit source
and destination addresses, the pocket switch scans the destination
address on each packet header received on a port, searches a dynamic
internal MAC routing table, and forwards the packet only if the data is
intended for a station beyond the local collision domain. If the data is
intended for a station on the collision domain from which the packet
was received, the pocket switch discards (filters) the packet, since any
signal on the local segment already has been received by all stations on
that segment. Baseline network performance also is improved because
switches do not forward collision signals or error packets from one
collision domain to another.
Powering Transition Networks’ Pocket Switch
To power ON the Transition Network’s pocket switch:
1. Locate the power receptacle on the back of the Transition
Network’s pocket switch
2. Connect the Transition Network’s pocket switch power
connector end of the power supply adapter to the power
receptacle on the back of the Transition Network’s pocket
switch.
3. Connect the external power connector end of the power supply
adapter to external AC power.
NOTE: After the power supply adapter is connected to the Transition
Network’s pocket switch and to external power, the green Power LED
is illuminated.
Transition Networks’
Pocket Switch
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