Computer Systems Technology DCN386 Lecture Notes - Lecture 7: Frame Check Sequence, Carrier-Sense Multiple Access, Maximum Transmission Unit
14 Dec 2015
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Document Summary
Frame relay - old wan technology, used but not being sold. The number represents the baseband (bandwidth), and the letter represents the type of cable. Identifies devices by using mac addresses (48 bits or 6 bytes) Length - 2 bytes ( the size of the frame) Standard max is dependent on the mtu(maximum transmission unit) Frame check sequence - *crc - 4 bytes (this is in the footer of the frame) If the crc is the same as the sender, the packet will pass, otherwise, it will be dropped. *preamble synchronizes time with the 7 bytes (10101010 ), and tells when to start reading data with the start of frame. Carrier sense - detects when someone is transmitting by looking at the current. Multiple access - determines whether to use half or full - duplex. Collision detection - random noise is created when packets collide, and corrupted data is generated.
