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Thursday, October 28, 2010

Alat Pemasang Kabel Fiber Optik

Hari ini syarikat yang datang bagi menyambung semula kabel fiber optik yang putus datang ke sekolah. Apa yang menarik minat adalah tool yang digunakan bagi menyambung kabel fiber optik tersebut. Sebenarnya memang tahu harga alat ini memang mahal tapi tak sangka la pula semahal itu. Satu set tool yang lengkap harganya sahaja boleh mencecah RM48 ribu. jadi tidak hairan la jika kos pemasangan kabel optik semangnya mahal.Pemasangan Wireless dan fibre optik telah dibuat selama 3 minggu yang lalu, namun belum siap sepenuhnya kerana ada beberapa barang seperti Rak server dan rak swisch belum sampai lagi. Difahamkan pihak pembekal baru mengagihkan barangan tersebut di sekolah-sekolah sekitar lembah kelang. Daerah sabak Bernam sekolah yang terpilih ialah SMKTarp, SMK Integrasi dan SMK Sungai Besar

Monday, October 25, 2010

Cable Network


Color Codes for RJ-45 Ethernet Plug

Eight-conductor data cable (Cat 3 or Cat 5) contains 4 pairs of wires. Each pair consists of a solid color wire and a white and color striped wire. Each of the pairs are twisted together. To maintain reliability on Ethernet, you should not untwist them any more than necessary (about 1/4 inch).

The pairs designated for 10BaseT Ethernet are orange and green. The other two pairs, brown and blue, are unused. The connections shown are specifically for an RJ45 plug. The wall jack may be wired in a different sequence because the wires may be crossed inside the jack. The jack should either come with a wiring diagram or at least designate pin numbers that you can match up to the color code below.

There are two wiring standards for these cables, called T-568A and T-568B. They differ only in pin assignments, not in uses of the various colors. The illustration above shows both standards. With the T-568B specification the orange and green pairs are located on pins 1, 2 and 3, 6 respectively. The T-568A specification reverses the orange and green connections, so that the blue and orange pairs are on the center 4 pins, which makes it more compatible with the telco voice connections.

Straight-Through vs Cross-Over

In general, the patch cords that you use with your Ethernet connections are "straight-through", which means that pin 1 of the plug on one end is connected to pin 1 of the plug on the other end (for either standard). The only time you cross connections in 10BaseT is when you connect two Ethernet devices directly together without a hub or connect two hubs together. Then you need a "cross-over" patch cable, which crosses the transmit and receive pairs. An easy way remember how to make a cross-over cable is to wire one end with the T-568A standard and the other with the T-568B standard.

Termination

UTP cables are terminated with standard connectors, jacks and punchdowns. The jack/plug is often referred to as a "RJ-45", but that's a telco designation for the "modular 8 pin connector" terminated with a USOC pinout used for telephones. The male connector on the end of a patchcord is called a "plug" and the receptacle on the wall outlet is a "jack."

In LANs, as spec'ed by 568, there are two possible pinouts, called T568A and T568B, that differ only in which color coded pairs are connected - pair 2 and 3 are reversed. Either work equally well, as long as you don't mix them! If you always use only one version, you're OK, but if you mix A and B in a cable run, you will get crossed pairs!

The cable pairs are color coded as

Pair 1 is white-blue/blue,
Pair 2 white-orange/orange,
Pair 3 is white-green/green
Pair 4 is white-brown/brown.

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