Transition Networks E-PSW-TX-02 Powering Transition Networks’ Pocket Switch, Ethernet Switching

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.

5 Transition Networks’

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.

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