Mike DelGaudio

[2:31:38 PM] student says: u there
[2:31:52 PM] Mike D. says: yo
[2:32:03 PM] student says: i need a calcultion
[2:32:11 PM] Mike D. says: shoot
[2:32:20 PM] Mike D. says: im all about calcultions
[2:32:25 PM] student says: of how long in meters is a 64 byte message
[2:32:33 PM] student says: on 10 bast T
[2:32:38 PM] student says: and 10 GbE
[2:32:55 PM] Mike D. says: Whisky Tango Foxtrot?
[2:33:08 PM] student says: yeah
[2:33:16 PM] student says: says here
[2:34:09 PM] student says: to first caluclate the number of seconds it would take to transmit the message then calc the number of meters the signal workd travel in time and you have the total lenght of the message
[2:34:29 PM] student says: given 10 base T
[2:34:42 PM] student says: and 40,000,000 meters per second
[2:34:53 PM] student says: 64 byte length
[2:35:36 PM] student says: its kind of like figuring out miles her hour
[2:35:59 PM] student says: we can travel 1 mile going 65 MPH
[2:36:39 PM] student says: but how long is a byte?
[2:36:54 PM] student says: that is what is confusing me
[2:37:08 PM] student says: seems like no matter what is always the same length
[2:37:17 PM] Mike D. says: show me your calc
[2:37:33 PM] student says: i have none yet
[2:37:37 PM] student says: trying to figure out
[2:38:16 PM] Mike D. says: I think what you need to remember is 10 base t is HOW MANY bits per second?
[2:38:29 PM] Mike D. says: 100? 10? megabits?
[2:39:13 PM] Mike D. says: and is 10BaseT megabits or megaBYTES per second?
[2:39:17 PM] student says: 10 Mbps per sec on 10 base t
[2:40:47 PM] Mike D. says: bits or bytes?
[2:41:23 PM] student says: bytes
[2:41:45 PM] student says: actually it does not say
[2:43:23 PM] Mike D. says: No I don’t think so… hang on one sec.
[2:43:46 PM] student says: think so about what…?
[2:44:01 PM] Mike D. says: OK… lets work this out.
[2:44:05 PM] Mike D. says: Here we go.
[2:44:15 PM] Mike D. says: Assume that 10BaseT is in megaBITS per second.
[2:44:26 PM] student says: ok
[2:44:28 PM] Mike D. says: open a google window.
[2:44:33 PM] Mike D. says: type the following:
[2:44:44 PM] Mike D. says: 10 megabits in bits
[2:44:46 PM] Mike D. says: and hit enter.
[2:45:25 PM] student says: ok
[2:45:39 PM] Mike D. says: you get 10485760 right?
[2:46:30 PM] student says: gave me links
[2:47:01 PM] Mike D. says: did you type exactly what I told you?
[2:47:16 PM] student says: i typed in bites
[2:47:19 PM] student says: got it now
[2:47:22 PM] student says: bits
[2:47:47 PM] student says: 10 485 760 bits
[2:52:50 PM] Mike D. says: so. if you have 10 million bits in one second.
[2:53:06 PM] Mike D. says: and 40 million meters in one second
[2:53:22 PM] Mike D. says: we should be able to figure out how many meters in one bit, right?
[2:53:58 PM] Mike D. says: How do you think we could do that?
[2:54:13 PM] student says: i’m thinking about what you are saying
[2:55:06 PM] Mike D. says: need me to explain more?
[2:55:31 PM] student says: 8 bits in a 64 byte message
[2:55:32 PM] student says: right
[2:55:55 PM] Mike D. says: so, how many meters is one bit in length?
[2:56:12 PM] student says: 512
[2:56:27 PM] Mike D. says: 512 is the bits in the 64byte message.
[2:56:51 PM] Mike D. says: just hold on to that for a second we’ll need that in a minutes.
[2:57:04 PM] Mike D. says: first lest figure out how many meters is one bit.
[2:57:20 PM] student says: so 512 bits in a 64 byte message
[2:57:27 PM] Mike D. says: correct.
[2:57:41 PM] Mike D. says: (Google: 64 bytes in bits)
[2:58:15 PM] Mike D. says: soooooo. how do we figure out how many meters a bit is?
[3:01:10 PM] student says: how many meters in a bit
[3:01:22 PM] Mike D. says: right…. how would you figure that out?
[3:02:06 PM] student says: not sure
[3:04:25 PM] Mike D. says: Alright. the thing we know for both meters and bits is PER SECOND, right?
[3:04:34 PM] student says: right
[3:04:43 PM] Mike D. says: there are 40 million meters and 10 million odd bits.
[3:05:14 PM] Mike D. says: so the MOST POSSIBLE bits you can fit in 40 million meters is 10.4 million
[3:05:40 PM] Mike D. says: with me so far?
[3:05:46 PM] student says: not sure how you are getting that
[3:06:30 PM] Mike D. says: Information travels over the cable at 40,000,000 meters per second.
[3:06:40 PM] student says: right
[3:06:59 PM] Mike D. says: So if you had a theoretical cable 40,000,000 meters in length, you would have ONE SECOND’s worth of data on it.
[3:07:18 PM] student says: right
[3:07:49 PM] Mike D. says: so if you chopped that cable into 10485760 equal sized pieces, you would have the length of one bit.
[3:08:31 PM] Mike D. says: because that number is the MOST bits you could possibly squeeze into that cable at one time.
[3:08:34 PM] student says: ok go back a second
[3:08:46 PM] student says: missing something here
[3:09:23 PM] Mike D. says: what are you missing?
[3:10:47 PM] Mike D. says: ?
[3:11:13 PM] student says: r you saying hypthectically speaking with the 10485760
[3:11:43 PM] student says: where you get that number
[3:12:04 PM] Mike D. says: Google: 10 megabits in bits
[3:12:19 PM] student says: why the 10 million
[3:13:22 PM] Mike D. says: 10 megabits is the capacity of 10BaseT network cable.
[3:13:41 PM] student says: gotcha
[3:14:36 PM] Mike D. says: so 10 megabits is 10485760 bits PER SECOND
[3:14:54 PM] student says: yeah
[3:15:32 PM] Mike D. says: so given a cable 40,000,000 meters in length, you can fit 10485760 bits onto it
[3:16:13 PM] Mike D. says: because those are both the max per second.
[3:16:33 PM] Mike D. says: you with me?
[3:16:49 PM] student says: no lost
[3:17:20 PM] Mike D. says: What is confusing you, do you think?
[3:17:52 PM] student says: i need to see thw caluculations I gues
[3:18:11 PM] Mike D. says: OK lets try this….
[3:20:13 PM] Mike D. says: do you see how a cable 40,000,000 meters in length represents one second?
[3:20:18 PM] student says: yes got it
[3:20:35 PM] Mike D. says: and how 10485760 is the bits in one second?
[3:20:45 PM] student says: yes got that too
[3:21:08 PM] Mike D. says: so if we press play on the network and bits start flying down the cable….
[3:21:16 PM] Mike D. says: and after one second we press pause.
[3:21:27 PM] Mike D. says: and look at the bits…
[3:21:30 PM] student says: we should have 10485760
[3:21:41 PM] Mike D. says: right.
[3:21:42 PM] student says: bits on a 10 base t cable
[3:21:57 PM] Mike D. says: right.
[3:22:20 PM] Mike D. says: so while the network is paused, we’ll cut the cable up into 10485760 pieces.
[3:22:31 PM] Mike D. says: all equal length.
[3:22:39 PM] student says: right
[3:22:53 PM] Mike D. says: each one of those pieces would be one bit long, right?
[3:23:12 PM] student says: right
[3:23:25 PM] student says: well not really
[3:23:31 PM] Mike D. says: why not?
[3:23:44 PM] student says: casue that is the equilvalent to 10 MB
[3:24:11 PM] Mike D. says: say that again.
[3:24:34 PM] student says: 10 MB = 10485760 bits is not really a single bit but a stream of bits
[3:24:44 PM] student says: right?
[3:25:03 PM] Mike D. says: right, but in our little experiment, we paused, so we can look at where each bit is at the moment in time.
[3:25:18 PM] Mike D. says: The first bit we sent down the wire is now 40,000,000 meters away
[3:25:28 PM] Mike D. says: the last bit we sent is right in front of us.
[3:26:43 PM] Mike D. says: you with me?
[3:27:14 PM] student says: so the total length of the message is 10485760
[3:27:42 PM] Mike D. says: that is the longest possible message we can transmit in one second.
[3:33:07 PM] student says: 3.81
[3:33:22 PM] student says: 40000000/10485760
[3:33:23 PM] Mike D. says: RIGHT! There you go… that is the length of ONE bit.
[3:33:37 PM] Mike D. says: so how long is 64 bytes?
[3:35:26 PM] student says: 1950.72
[3:35:36 PM] student says: 3.81 x 512
[3:36:06 PM] Mike D. says: There you go, You might want to extend that out a few decimal places.
[3:36:28 PM] Mike D. says: Google: (40000000/10485760)*(64 * 8 )
[3:38:27 PM] student says: cool