Bandwidth and insertion delay: definitions needed
Ah hello.
I have been advised in person by a trustworthy source that the "bandwidth" of a device, when expressed in kb/sec, is the number of bits that the device is capable of writing to the wire in a second. It was also stated that this is synonymous with "insertion delay".
Now, this makes sense, but since I cannot find anything on the net using this same terminology, I am unsure.
1) Is this the correct definition of "bandwidth"?
2) Is "insertion delay" the same as bandwidth? Again, there doesn't seem to be anything confirming either way.
TIA
I have been advised in person by a trustworthy source that the "bandwidth" of a device, when expressed in kb/sec, is the number of bits that the device is capable of writing to the wire in a second. It was also stated that this is synonymous with "insertion delay".
Now, this makes sense, but since I cannot find anything on the net using this same terminology, I am unsure.
1) Is this the correct definition of "bandwidth"?
2) Is "insertion delay" the same as bandwidth? Again, there doesn't seem to be anything confirming either way.
TIA
Insertion delay is usually called latency outside pornographic circles.
Normally packets to be sent out to some interface are arranged into sort of queue, then they get out at interface with transmit delay applying. If the queue is too big or there are too many queues one calls it bufferbloat.
Normally packets to be sent out to some interface are arranged into sort of queue, then they get out at interface with transmit delay applying. If the queue is too big or there are too many queues one calls it bufferbloat.
ASKER
Er, ok...
So it seems that bandwidth is not insertion delay, but I'm still unsure on bandwidth:
All of this has come about as a result of http://en.wikipedia.org/wiki/Bandwidth-delay_product:
"The result, an amount of data measured in bits (or bytes), is equivalent to the maximum amount of data on the network circuit at any given time, i.e., data that has been transmitted but not yet acknowledged."
So if I write bits out at a speed of 512kb/sec, then the maximum amount of data that can possibly be unacknowledged is indeed (the rate at which we can send bits out) * (how long it takes us to get back our first ACK). This makes sense, but it is never worded as such when looking up "bandwidth".
Can someone please clarify??
So it seems that bandwidth is not insertion delay, but I'm still unsure on bandwidth:
All of this has come about as a result of http://en.wikipedia.org/wiki/Bandwidth-delay_product:
"The result, an amount of data measured in bits (or bytes), is equivalent to the maximum amount of data on the network circuit at any given time, i.e., data that has been transmitted but not yet acknowledged."
So if I write bits out at a speed of 512kb/sec, then the maximum amount of data that can possibly be unacknowledged is indeed (the rate at which we can send bits out) * (how long it takes us to get back our first ACK). This makes sense, but it is never worded as such when looking up "bandwidth".
Can someone please clarify??
It changes greatly from your description in October 1989, RFC1122
ASKER
?
What I quoted from Wikipedia is wrong - are you saying that? I'm sorry but I don't know what you are getting at with your last comment...
What I quoted from Wikipedia is wrong - are you saying that? I'm sorry but I don't know what you are getting at with your last comment...
Depends on what is the definition of network circuit. Take a good read in sources other than wikipedia
BDP is commonly ping delay x bandwidth. like .3s across atlantic
BDP is commonly ping delay x bandwidth. like .3s across atlantic
ASKER
David, do you have anything else to add to this?
e.g. with UDP or Ethernet you will not receive any acknowledgement, with wifi,dsl or TCP you will get them even re-transmitted in worst cases....
ASKER
OK, so I have my definition of insertion delay, but I'm still not sure on bandwidth...
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ASKER
OK I'm not sure that insertion delay is
the time from when you generate the data to be sent and the time it is acted upon by the receiver
...surely that is half the RTT plus the latency in the receiving TCP stack in getting the data up to the application layer? I'm gonna do some more digging/speaking to people, will post back anything interesting. Either way I'll share the points here for effort made.
the time from when you generate the data to be sent and the time it is acted upon by the receiver
...surely that is half the RTT plus the latency in the receiving TCP stack in getting the data up to the application layer? I'm gonna do some more digging/speaking to people, will post back anything interesting. Either way I'll share the points here for effort made.
ASKER
Thanks both. It seems that these terms are not easily defined, and I guess the answers may depend on what the expertise of those asked is; an electronics expert will most likely give a varying answer to a higher level network specialist.
for instance you change the input to a flip flop and there is a delay before the output changes.
clock insertion delay is the delay from the clock definition point to clock pin.due to propagation time.
http://bit.ly/17Tm0V7