74 4A 112 01001010 90 5A 132 01011010 106 6A 152 01101010 122 7A 172 01111010 75 4B 113 01001011 91 5B 133 01011011 107 6B 153 01101011 123 7B 173 01111011 76 4C 114 01001100 92 5C 134 01011100 108 6C 154 01101100 124 7C 174 01111100 77 4D 115 01001101 93 5D 135 01011101 109 6D 155 01101101 125 7D 175 01111101 78 4E 116 01001110 94 5E 136 01011110 110 6E 156 01101110 126 7E 176 01111110 79 4F 117 01001111 95 5F 137 01011111 111 6F 157 01101111 127 7F 177 01111111 Dec Hex Oct Bin Dec Hex Oct Bin Dec Hex Oct Bin Dec Hex Oct Bin 128 80 200 10000000 144 90 220 10010000 160 A0 240 10100000 176 B0 260 10110000
synchronization Frame Synchronization ~ Asynchronous Transmission using STX & ETX 1. obtain recoveryoDLC service modes:> Connectionoriented vs connectionless Example of PPP byte stuffing: bit synchronization with 1st SYN starts receiving bits 2. enter hunt mode for byte synchronization: 1. Reliable/virtual-circuit (connection-oriented mode) users establish Flag=0x7E (01111110), Control escape=0x7D (01111101) after each bit -> check last 8 bits 3. frame synchronization: process each byte looking for STX - after connection before sending information packets errors dealt with using ACKs, Any occurrence of flag or control escape inside of frame is STX, read frame contents look for ETX after ETX, transmitter can maintain synch by sending SYNs, NACKS2
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