Bits in a byte question...

[AMDPwred]

If anyone could explain this to me, I'd be most thankful.

"A data transfer between two communications devices takes place at 2Mbps. If we need to transfer 27 MB worth of data, what is the minimum amount of time it will take to complete the transfer?"

I'm not looking for just the answer, I'd really like it if someone could explain the conversions here.

 

[Heisenberg]

8 bits = 1 byte. Do the math.

 

[neonerd]

Heisenberg beat me to it

 

[AMDPwred]

Is it 108 secs?

2/8 = .25 MBps
27/.25 = 108 sec

 

[NikPreviousAcct]

4 bits = nibble (serious)
8 bits = byte
1024 bits = kilobit (kb)
1024 bytes = kilobyte (KB)
1024 kilobits = megabit (mb)
1024 kilobytes = megabyte (MB)

et al

 

[Colt45]

8 bits = 1 byte

but the equation doesn't work like that. TCP/IP has overhead.

 

[lavagirl669]

Originally posted by: Nik
4 bits = nibble (serious)
8 bits = byte
1024 bits = kilobit (kb)
1024 bytes = kilobyte (KB)
1024 kilobits = megabit (mb)
1024 kilobytes = megabyte (MB)

et al

/me ponders "nibble"

 

[AMDPwred]

Originally posted by: Colt45
8 bits = 1 byte

but the equation doesn't work like that. TCP/IP has overhead.

Yeah, we're going at a really basic level so far.

 

[SWScorch]

Originally posted by: lavagirl669

Originally posted by: Nik
4 bits = nibble (serious)
8 bits = byte
1024 bits = kilobit (kb)
1024 bytes = kilobyte (KB)
1024 kilobits = megabit (mb)
1024 kilobytes = megabyte (MB)

et al

/me ponders "nibble"

*psst* A nibble is half of a byte

 

[mundane]

Originally posted by: AMDPwred
Is it 108 secs?

2/8 = .25 MBps
27/.25 = 108 sec

That's how long it'll take the sending device from first bit to last - but you also need to take into account the delta t on the pipe between the devices themselves. (Is latency the right term?) You tack on the latency to 108 sec, and you have the minimum time required to transfer the full 27MB.

 

[NikPreviousAcct]

Originally posted by: SWScorch

Originally posted by: lavagirl669

Originally posted by: Nik
4 bits = nibble (serious)
8 bits = byte
1024 bits = kilobit (kb)
1024 bytes = kilobyte (KB)
1024 kilobits = megabit (mb)
1024 kilobytes = megabyte (MB)

et al

/me ponders "nibble"

*psst* A nibble is half of a byte

Halfabyte? HB?



ByteJob, anyone? BJ? :laugh:

 

[StageLeft]

Is there a start and stop bit in internet traffic? Ie. a byte is actually 10 bits?

 

[NikPreviousAcct]

No, Skoorb, there isn't. The "start" and "stop" of a successful transfer are included in the packet info. It's called overhead.

 

[MacBaine]

What about 6 bit bytes? HUH??? HUH???

 

[StageLeft]

Originally posted by: Nik
No, Skoorb, there isn't. The "start" and "stop" of a successful transfer are included in the packet info. It's called overhead.

How much overhead is there normally? I suppose that would depend on your connection and protocol, but is there general overhead? What's the average packet size, and if a packet is 32KB of data, how much of that would be overhead to ensure the entire packet arrived?

 

[frodrick]

Originally posted by: AMDPwred
Is it 108 secs?

2/8 = .25 MBps
27/.25 = 108 sec

That would be correct, except 2Mbps != 2048bps.

27MB * 1024B * 8b = 221184b
2Mbps * 1000bps = 2000bps

221184b / 2000bps = 110.592s

 

[NikPreviousAcct]

Originally posted by: Skoorb

Originally posted by: Nik
No, Skoorb, there isn't. The "start" and "stop" of a successful transfer are included in the packet info. It's called overhead.

How much overhead is there normally? I suppose that would depend on your connection and protocol, but is there general overhead? What's the average packet size, and if a packet is 32KB of data, how much of that would be overhead to ensure the entire packet arrived?

Would I be correct in assuming that you're looking for an average percentage? I'm not sure. I'm not sure if you can find, isolate, and open a single packet in, say, notepad or something.

 

[GroundZero]

the answer is a bunny named george, and i wil hugg him and love him and pet him and squeaze him

 

[Descartes]

Originally posted by: Nik

Originally posted by: Skoorb

Originally posted by: Nik
No, Skoorb, there isn't. The "start" and "stop" of a successful transfer are included in the packet info. It's called overhead.

How much overhead is there normally? I suppose that would depend on your connection and protocol, but is there general overhead? What's the average packet size, and if a packet is 32KB of data, how much of that would be overhead to ensure the entire packet arrived?

Would I be correct in assuming that you're looking for an average percentage? I'm not sure. I'm not sure if you can find, isolate, and open a single packet in, say, notepad or something.

There's no average percentage. The packet header for all protocols is defined, and for TCP it's 256 bits.

 

[StageLeft]

Originally posted by: Descartes

Originally posted by: Nik

Originally posted by: Skoorb

Originally posted by: Nik
No, Skoorb, there isn't. The "start" and "stop" of a successful transfer are included in the packet info. It's called overhead.

How much overhead is there normally? I suppose that would depend on your connection and protocol, but is there general overhead? What's the average packet size, and if a packet is 32KB of data, how much of that would be overhead to ensure the entire packet arrived?

Would I be correct in assuming that you're looking for an average percentage? I'm not sure. I'm not sure if you can find, isolate, and open a single packet in, say, notepad or something.

There's no average percentage. The packet header for all protocols is defined, and for TCP it's 256 bits.

How big is a TCP packet?

 

[NikPreviousAcct]

Originally posted by: Skoorb

Originally posted by: Descartes

Originally posted by: Nik

Originally posted by: Skoorb

Originally posted by: Nik
No, Skoorb, there isn't. The "start" and "stop" of a successful transfer are included in the packet info. It's called overhead.

How much overhead is there normally? I suppose that would depend on your connection and protocol, but is there general overhead? What's the average packet size, and if a packet is 32KB of data, how much of that would be overhead to ensure the entire packet arrived?

Would I be correct in assuming that you're looking for an average percentage? I'm not sure. I'm not sure if you can find, isolate, and open a single packet in, say, notepad or something.

There's no average percentage. The packet header for all protocols is defined, and for TCP it's 256 bits.

How big is a TCP packet?

That brings up an interesting question... if a header exists, does a footer also exist? I would think it does, but I never really thought about it. Is it also 256 bits? I would think that it's smaller to just denote the end of the packet.