Why did the Ethernet guys pick a block size of 1500?
Token Ring and Ethernet
Token ring 64000bytes, why was this rule their, Why did IBM HAVE A BIG BLOCK SIZE?, have this in the back of your mind, why is it this?
Ethernet knew that every machine on a bus network will transfer data, and they will send it at the same time when they do it will be lost, if your designing a protocol so after theirs not a lot of collisions, there for if there is no data collisions you transfer bigger blocks…which would be Token Ring...
Why did it disappear?
Datacome situation you have not heard about this before, multiplexing, simple concept, means how does a device take multiple inputs, and transmit in one physical light, lots of ways of doing this, televisions signals are multiplex signals, or sympatico, you use multiplexing, Rogers is using the existing multiplexing signals the tv use……telephone gets mingled with other peoples voices …multiplexing.
This is data signals, if you got digital info that was once multiplexed, talk about time division multiplexing, TDM, we do this for money, this allows datacom people to transfer through one visible line multiple signals.
Leased Digital Lines come as low as
24000
48000
96000
640000
T1 1.54MBPS
96000 most common line speed, because in the bank branch is all text.
Pretend we are sending 24000, then we had a device a MUX and MUX at head office, you save money,
Time Division Multiplexer, next week, statistical multiplexer, the MUX reads one char from the input port and build a FRAME of data, every signal is 4000$ so if you MUX 9600kps you save only $500, you save a little bit,
He wants to hear about these on the test
Statistical MUX (Stat MUX) and how you can save a fortune, you can make a fortune
, know more about them the second one is the T1 MUX, a huge investment.
T1 MUX standard digital line speed 1.54bps, T1 Laid down by phone companies LONG time ago, now their laying fibre-optics replacing old digital copper wire NICs, T1 leased to co-operations. Why do companies invest money in these, long distance without the T1 MUX,
PBS – Private Bank Exchange how little offices hook up their phones
U hook up the phones and the computer to the T1 MUX works like a time division MUX, except you can have dozens of input lines, 24 phone calls to one T1 MUX 1.53, take 8 bits from each input port and build a frame, each frame 192bits, 8 bits x 24, at the end of 192 bits it puts a extra bit , separating bits, that was fine for voice, T1 are integrating these things with computer work so now its just data,
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