Computer Network: Using Star Topology

 In a star topology, each device has dedicated point to point link only to a central controller or concentrator that usually called a hub. Computer workstation are not directly linked to each other. If one workstation (A) want to send data to other workstation (B), first workstation A sends data to a hub and then the hub retransmit data that was received to the destination address is workstation B.

To send data from workstation A is reference on OSI architecture with is complete with header contain address and trailer as error correction. Logic address in header this value is dynamic. When Work Station A send data to Work Station B, the first logic address value at bit stream data is number IP Hub, but the physical address always is the last destination address is workstation B.

How Fax Works? (Function of Frame Protocol)

 The communication between two fax machines is as follows:

1.            The transmitter calls the receiving fax machine. The transmitter will generate the dialing signal and then continuously send out a CNG tone which is used to signal an auto receive fax machine that another fax is making the call. This CNG tone is also used with allot of line sharing devices today.

2.            The phone line on the receiving side will ring and the receiving fax will pick up the line and send out a CED tone. This tone only tells the transmitter that it has connected to a fax machine.

3.            The receiving fax then sends out a PREAMBLE signal. This signal is a series of flags that are sent out to condition the phone line and to synchronize the two modems. A PREAMBLE will be generated just before any binary information is sent over the phone line.

Dasar Komunikasi Data: High Level Data Link Control (HDLC)

TEORI DASAR HDLC

Struktur Frame

HDLC menggunakan transmisi synchronous. Semua transnisi berbentuk frame, dan format frame tunggal memadai untuk seluruh jenis pertukaran data dan kontrol.

            Hal-hal seperti tanda, alamat, dan, kontrol yang mendahului hal-hal yang berkaitan dengan informasi disebut sebagai; header (kepala). Sedangkan untuk FCS dan tanda yang mengikuti hal-hal yang berkaitan dengan data disebut sebagai gandengan.