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* [Bloat] Hey, all, what about bandlength?
@ 2023-04-08 15:32 Dave Collier-Brown
  2023-04-08 18:49 ` Michael Richardson
  0 siblings, 1 reply; 9+ messages in thread
From: Dave Collier-Brown @ 2023-04-08 15:32 UTC (permalink / raw)
  To: bloat

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Dave was talking about metrics the other day, attempts like Apple's round-trips per minute.

They he said "bandlength"

That sounded like an odd name, but the idea was cool:

If I have a bandwidth of 1 Mbit/S, but it takes 2 seconds to deliver 1 Mbit,
do I have a bandlength of only 1/2 Mbit/S?

--dave c-b

--
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
dave.collier-brown@indexexchange.com<mailto:dave.collier-brown@indexexchange.com> |              -- Mark Twain


CONFIDENTIALITY NOTICE AND DISCLAIMER : This telecommunication, including any and all attachments, contains confidential information intended only for the person(s) to whom it is addressed. Any dissemination, distribution, copying or disclosure is strictly prohibited and is not a waiver of confidentiality. If you have received this telecommunication in error, please notify the sender immediately by return electronic mail and delete the message from your inbox and deleted items folders. This telecommunication does not constitute an express or implied agreement to conduct transactions by electronic means, nor does it constitute a contract offer, a contract amendment or an acceptance of a contract offer. Contract terms contained in this telecommunication are subject to legal review and the completion of formal documentation and are not binding until same is confirmed in writing and has been signed by an authorized signatory.

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^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [Bloat] Hey, all, what about bandlength?
  2023-04-08 15:32 [Bloat] Hey, all, what about bandlength? Dave Collier-Brown
@ 2023-04-08 18:49 ` Michael Richardson
  2023-04-08 22:22   ` Jonathan Morton
  2023-04-09  1:39   ` Dave Collier-Brown
  0 siblings, 2 replies; 9+ messages in thread
From: Michael Richardson @ 2023-04-08 18:49 UTC (permalink / raw)
  To: Dave Collier-Brown; +Cc: bloat

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Dave Collier-Brown via Bloat <bloat@lists.bufferbloat.net> wrote:
    > They he said "bandlength"

    > That sounded like an odd name, but the idea was cool:

    > If I have a bandwidth of 1 Mbit/S, but it takes 2 seconds to deliver 1
    > Mbit, do I have a bandlength of only 1/2 Mbit/S?

Is that because there is 2seconds of delay?


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^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [Bloat] Hey, all, what about bandlength?
  2023-04-08 18:49 ` Michael Richardson
@ 2023-04-08 22:22   ` Jonathan Morton
  2023-04-09  1:39   ` Dave Collier-Brown
  1 sibling, 0 replies; 9+ messages in thread
From: Jonathan Morton @ 2023-04-08 22:22 UTC (permalink / raw)
  To: Michael Richardson; +Cc: Dave Collier-Brown, bloat

> On 8 Apr, 2023, at 9:49 pm, Michael Richardson via Bloat <bloat@lists.bufferbloat.net> wrote:
> 
>> If I have a bandwidth of 1 Mbit/S, but it takes 2 seconds to deliver 1
>> Mbit, do I have a bandlength of only 1/2 Mbit/S?
> 
> Is that because there is 2seconds of delay?

It could merely be that, due to new-flow effects, the effective utilisation of the path is only 50% over those two seconds.  A longer flow might have better utilisation in its later stages.

 - Jonathan Morton

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [Bloat] Hey, all, what about bandlength?
  2023-04-08 18:49 ` Michael Richardson
  2023-04-08 22:22   ` Jonathan Morton
@ 2023-04-09  1:39   ` Dave Collier-Brown
  2023-04-09  2:32     ` Michael Richardson
  1 sibling, 1 reply; 9+ messages in thread
From: Dave Collier-Brown @ 2023-04-09  1:39 UTC (permalink / raw)
  To: Michael Richardson; +Cc: bloat

On 4/8/23 14:49, Michael Richardson wrote:

> Dave Collier-Brown via Bloat<bloat@lists.bufferbloat.net>  wrote:
>      > They he said "bandlength"
>
>      > That sounded like an odd name, but the idea was cool:
>
>      > If I have a bandwidth of 1 Mbit/S, but it takes 2 seconds to deliver 1
>      > Mbit, do I have a bandlength of only 1/2 Mbit/S?
>
> Is that because there is 2seconds of delay?
Well, 2 seconds elapsed time, 1 of which is delay.

--dave

--
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
dave.collier-brown@indexexchange.com |              -- Mark Twain


CONFIDENTIALITY NOTICE AND DISCLAIMER : This telecommunication, including any and all attachments, contains confidential information intended only for the person(s) to whom it is addressed. Any dissemination, distribution, copying or disclosure is strictly prohibited and is not a waiver of confidentiality. If you have received this telecommunication in error, please notify the sender immediately by return electronic mail and delete the message from your inbox and deleted items folders. This telecommunication does not constitute an express or implied agreement to conduct transactions by electronic means, nor does it constitute a contract offer, a contract amendment or an acceptance of a contract offer. Contract terms contained in this telecommunication are subject to legal review and the completion of formal documentation and are not binding until same is confirmed in writing and has been signed by an authorized signatory.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [Bloat] Hey, all, what about bandlength?
  2023-04-09  1:39   ` Dave Collier-Brown
@ 2023-04-09  2:32     ` Michael Richardson
  2023-04-09 20:06       ` Dave Collier-Brown
  0 siblings, 1 reply; 9+ messages in thread
From: Michael Richardson @ 2023-04-09  2:32 UTC (permalink / raw)
  To: Dave Collier-Brown; +Cc: bloat

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Dave Collier-Brown <dave.collier-Brown@indexexchange.com> wrote:
    >> Dave Collier-Brown via Bloat<bloat@lists.bufferbloat.net> wrote: >
    >> They he said "bandlength"
    >>
    >> > That sounded like an odd name, but the idea was cool:
    >>
    >> > If I have a bandwidth of 1 Mbit/S, but it takes 2 seconds to deliver
    >> 1 > Mbit, do I have a bandlength of only 1/2 Mbit/S?
    >>
    >> Is that because there is 2seconds of delay?

    > Well, 2 seconds elapsed time, 1 of which is delay.

Ah, would that include the delay to ask for the data?
(A DNS request, or an HTTP GET)


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^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [Bloat] Hey, all, what about bandlength?
  2023-04-09  2:32     ` Michael Richardson
@ 2023-04-09 20:06       ` Dave Collier-Brown
  2023-04-09 23:04         ` David Lang
  0 siblings, 1 reply; 9+ messages in thread
From: Dave Collier-Brown @ 2023-04-09 20:06 UTC (permalink / raw)
  To: bloat

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Consider a connection to my ISP as being an empty water-pipe, and I only want to measure the flow from the waterworks to me. In this case the waterworks is Rogers in Toronto, and the numbers come from me measuring the link with the Waveform bufferbloat tool.

The ISP promises me 1 Gbit/s of water.  OK, there is no such thing, but you get the idea (;-))

Let's consider the no-latency case.

  *   The ISP turns on the tap, and it takes half an RTT to get to me, one way.  Let that be 1 millisecond, 0.001s of delay.
  *   Once the delay is over, I get (1.0s - 0.001s) * 1 Gbit/s = 0.999 Gb/s. The 0.999 seconds is transfer time, and that transfer is at full speed of the pipe, so it adds up to 0.999 Gb/s
  *   That's pretty good.

Now let's consider the best possible case where there is latency, but only one delay of 0.456s.  That basically means that only one transfer happens in the second, so there is only once change for latency to hurt me.

  *   the one-way delay is still 0.001s, but there is also 0.231s of latency, for a delay of 0.232s
  *   (1.0s - (0.001s + 0.231s) ) * 1 Gbit/s =
  *   1.0s - 0.232s = 0.549s  * 1 Gbit/s = 0.768 GB/s
  *   Cut by a quarter, by one packet's delay

What about the worst case?

  *   It's not worst, but a pretty common case is a busy link with 1500-byte packets
  *   One packet is 12,000 bits
  *   In one second we can transfer 1,000,000,000 bits / 12,000bits/packet = 83,333.3 packets
  *   Maybe that many delays, too?
  *   Fortunately, no

I personally observed 456.2 Mbit/s, about 54% of a gigabit at home, so it's more like the latency cut my bandwidth in half

--dave


On 4/8/23 22:32, Michael Richardson via Bloat wrote:


Dave Collier-Brown <dave.collier-Brown@indexexchange.com><mailto:dave.collier-Brown@indexexchange.com> wrote:
    >> Dave Collier-Brown via Bloat<bloat@lists.bufferbloat.net><mailto:bloat@lists.bufferbloat.net> wrote: >
    >> They he said "bandlength"
    >>
    >> > That sounded like an odd name, but the idea was cool:
    >>
    >> > If I have a bandwidth of 1 Mbit/S, but it takes 2 seconds to deliver
    >> 1 > Mbit, do I have a bandlength of only 1/2 Mbit/S?
    >>
    >> Is that because there is 2seconds of delay?

    > Well, 2 seconds elapsed time, 1 of which is delay.

Ah, would that include the delay to ask for the data?
(A DNS request, or an HTTP GET)




CONFIDENTIALITY NOTICE AND DISCLAIMER : This telecommunication, including any and all attachments, contains confidential information intended only for the person(s) to whom it is addressed. Any dissemination, distribution, copying or disclosure is strictly prohibited and is not a waiver of confidentiality. If you have received this telecommunication in error, please notify the sender immediately by return electronic mail and delete the message from your inbox and deleted items folders. This telecommunication does not constitute an express or implied agreement to conduct transactions by electronic means, nor does it constitute a contract offer, a contract amendment or an acceptance of a contract offer. Contract terms contained in this telecommunication are subject to legal review and the completion of formal documentation and are not binding until same is confirmed in writing and has been signed by an authorized signatory.

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^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [Bloat] Hey, all, what about bandlength?
  2023-04-09 20:06       ` Dave Collier-Brown
@ 2023-04-09 23:04         ` David Lang
  2023-04-10 11:04           ` Dave Collier-Brown
  2023-04-10 11:30           ` Sebastian Moeller
  0 siblings, 2 replies; 9+ messages in thread
From: David Lang @ 2023-04-09 23:04 UTC (permalink / raw)
  To: Dave Collier-Brown; +Cc: bloat

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TCP ramps up it's speed fairly slowly, and backs off fairly drastically when it 
is told (via ECN or a dropped packet) that it has hit the limit. As a result, a 
single TCP session is not going to fully utilize a connection. There are people 
who do large, high speed transfers over long distances on a regular basis (think 
movie studios sending uncompressed movie footage around the world for 
processing). To fully utilize their bandwidth, they use protocols that involve 
lots of connections operating in parallel

David Lang

On Sun, 9 Apr 2023, Dave Collier-Brown via Bloat wrote:

> Date: Sun, 9 Apr 2023 16:06:54 -0400
> From: Dave Collier-Brown via Bloat <bloat@lists.bufferbloat.net>
> Reply-To: Dave Collier-Brown <dave.collier-Brown@indexexchange.com>
> To: bloat@lists.bufferbloat.net
> Subject: Re: [Bloat] Hey, all, what about bandlength?
> 
> Consider a connection to my ISP as being an empty water-pipe, and I only want 
> to measure the flow from the waterworks to me. In this case the waterworks is 
> Rogers in Toronto, and the numbers come from me measuring the link with the 
> Waveform bufferbloat tool.
>
> The ISP promises me 1 Gbit/s of water.  OK, there is no such thing, but you 
> get the idea (;-))
>
> Let's consider the no-latency case.
>
> *   The ISP turns on the tap, and it takes half an RTT to get to me, one 
> way.  Let that be 1 millisecond, 0.001s of delay.
> *   Once the delay is over, I get (1.0s - 0.001s) * 1 Gbit/s = 0.999 Gb/s. 
> The 0.999 seconds is transfer time, and that transfer is at full speed of the 
> pipe, so it adds up to 0.999 Gb/s
> *   That's pretty good.
>
> Now let's consider the best possible case where there is latency, but only 
> one delay of 0.456s.  That basically means that only one transfer happens in 
> the second, so there is only once change for latency to hurt me.
>
> *   the one-way delay is still 0.001s, but there is also 0.231s of latency, 
> for a delay of 0.232s
> *   (1.0s - (0.001s + 0.231s) ) * 1 Gbit/s =
> *   1.0s - 0.232s = 0.549s  * 1 Gbit/s = 0.768 GB/s
> *   Cut by a quarter, by one packet's delay
>
> What about the worst case?
>
> *   It's not worst, but a pretty common case is a busy link with 1500-byte 
> packets
> *   One packet is 12,000 bits
> *   In one second we can transfer 1,000,000,000 bits / 12,000bits/packet = 
> 83,333.3 packets
> *   Maybe that many delays, too?
> *   Fortunately, no
>
> I personally observed 456.2 Mbit/s, about 54% of a gigabit at home, so it's 
> more like the latency cut my bandwidth in half
>
> --dave
>
>
> On 4/8/23 22:32, Michael Richardson via Bloat wrote:
>
>
> Dave Collier-Brown 
> <dave.collier-Brown@indexexchange.com><mailto:dave.collier-Brown@indexexchange.com> 
> wrote:
>   >> Dave Collier-Brown via 
> Bloat<bloat@lists.bufferbloat.net><mailto:bloat@lists.bufferbloat.net> wrote: 
>>
>   >> They he said "bandlength"
>   >>
>   >> > That sounded like an odd name, but the idea was cool:
>   >>
>   >> > If I have a bandwidth of 1 Mbit/S, but it takes 2 seconds to deliver
>   >> 1 > Mbit, do I have a bandlength of only 1/2 Mbit/S?
>   >>
>   >> Is that because there is 2seconds of delay?
>
>   > Well, 2 seconds elapsed time, 1 of which is delay.
>
> Ah, would that include the delay to ask for the data?
> (A DNS request, or an HTTP GET)
>
>
>
>
> CONFIDENTIALITY NOTICE AND DISCLAIMER : This telecommunication, including any 
> and all attachments, contains confidential information intended only for the 
> person(s) to whom it is addressed. Any dissemination, distribution, copying 
> or disclosure is strictly prohibited and is not a waiver of confidentiality. 
> If you have received this telecommunication in error, please notify the 
> sender immediately by return electronic mail and delete the message from your 
> inbox and deleted items folders. This telecommunication does not constitute 
> an express or implied agreement to conduct transactions by electronic means, 
> nor does it constitute a contract offer, a contract amendment or an 
> acceptance of a contract offer. Contract terms contained in this 
> telecommunication are subject to legal review and the completion of formal 
> documentation and are not binding until same is confirmed in writing and has 
> been signed by an authorized signatory.
>

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_______________________________________________
Bloat mailing list
Bloat@lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/bloat

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [Bloat] Hey, all, what about bandlength?
  2023-04-09 23:04         ` David Lang
@ 2023-04-10 11:04           ` Dave Collier-Brown
  2023-04-10 11:30           ` Sebastian Moeller
  1 sibling, 0 replies; 9+ messages in thread
From: Dave Collier-Brown @ 2023-04-10 11:04 UTC (permalink / raw)
  To: bloat

Which fits the word "bandlength" better than my discussion, which was an
experiment in explaining that latency has a cost to someone who doesn't
know waht it means.

--dave

On 4/9/23 19:04, David Lang via Bloat wrote:
> TCP ramps up it's speed fairly slowly, and backs off fairly
> drastically when it is told (via ECN or a dropped packet) that it has
> hit the limit. As a result, a single TCP session is not going to fully
> utilize a connection. There are people who do large, high speed
> transfers over long distances on a regular basis (think movie studios
> sending uncompressed movie footage around the world for processing).
> To fully utilize their bandwidth, they use protocols that involve lots
> of connections operating in parallel
>
> David Lang
>
> On Sun, 9 Apr 2023, Dave Collier-Brown via Bloat wrote:
>
>> Date: Sun, 9 Apr 2023 16:06:54 -0400
>> From: Dave Collier-Brown via Bloat <bloat@lists.bufferbloat.net>
>> Reply-To: Dave Collier-Brown <dave.collier-Brown@indexexchange.com>
>> To: bloat@lists.bufferbloat.net
>> Subject: Re: [Bloat] Hey, all, what about bandlength?
>>
>> Consider a connection to my ISP as being an empty water-pipe, and I
>> only want to measure the flow from the waterworks to me. In this case
>> the waterworks is Rogers in Toronto, and the numbers come from me
>> measuring the link with the Waveform bufferbloat tool.
>>
>> The ISP promises me 1 Gbit/s of water.  OK, there is no such thing,
>> but you get the idea (;-))
>>
>> Let's consider the no-latency case.
>>
>> *   The ISP turns on the tap, and it takes half an RTT to get to me,
>> one way.  Let that be 1 millisecond, 0.001s of delay.
>> *   Once the delay is over, I get (1.0s - 0.001s) * 1 Gbit/s = 0.999
>> Gb/s. The 0.999 seconds is transfer time, and that transfer is at
>> full speed of the pipe, so it adds up to 0.999 Gb/s
>> *   That's pretty good.
>>
>> Now let's consider the best possible case where there is latency, but
>> only one delay of 0.456s.  That basically means that only one
>> transfer happens in the second, so there is only once change for
>> latency to hurt me.
>>
>> *   the one-way delay is still 0.001s, but there is also 0.231s of
>> latency, for a delay of 0.232s
>> *   (1.0s - (0.001s + 0.231s) ) * 1 Gbit/s =
>> *   1.0s - 0.232s = 0.549s  * 1 Gbit/s = 0.768 GB/s
>> *   Cut by a quarter, by one packet's delay
>>
>> What about the worst case?
>>
>> *   It's not worst, but a pretty common case is a busy link with
>> 1500-byte packets
>> *   One packet is 12,000 bits
>> *   In one second we can transfer 1,000,000,000 bits /
>> 12,000bits/packet = 83,333.3 packets
>> *   Maybe that many delays, too?
>> *   Fortunately, no
>>
>> I personally observed 456.2 Mbit/s, about 54% of a gigabit at home,
>> so it's more like the latency cut my bandwidth in half
>>
>> --dave
>>
>>
>> On 4/8/23 22:32, Michael Richardson via Bloat wrote:
>>
>>
>> Dave Collier-Brown
>> <dave.collier-Brown@indexexchange.com><mailto:dave.collier-Brown@indexexchange.com>
>> wrote:
>>   >> Dave Collier-Brown via
>> Bloat<bloat@lists.bufferbloat.net><mailto:bloat@lists.bufferbloat.net>
>> wrote:
>>>
>>   >> They he said "bandlength"
>>   >>
>>   >> > That sounded like an odd name, but the idea was cool:
>>   >>
>>   >> > If I have a bandwidth of 1 Mbit/S, but it takes 2 seconds to
>> deliver
>>   >> 1 > Mbit, do I have a bandlength of only 1/2 Mbit/S?
>>   >>
>>   >> Is that because there is 2seconds of delay?
>>
>>   > Well, 2 seconds elapsed time, 1 of which is delay.
>>
>> Ah, would that include the delay to ask for the data?
>> (A DNS request, or an HTTP GET)
>>
>>
>>
>>
>> CONFIDENTIALITY NOTICE AND DISCLAIMER : This telecommunication,
>> including any and all attachments, contains confidential information
>> intended only for the person(s) to whom it is addressed. Any
>> dissemination, distribution, copying or disclosure is strictly
>> prohibited and is not a waiver of confidentiality. If you have
>> received this telecommunication in error, please notify the sender
>> immediately by return electronic mail and delete the message from
>> your inbox and deleted items folders. This telecommunication does not
>> constitute an express or implied agreement to conduct transactions by
>> electronic means, nor does it constitute a contract offer, a contract
>> amendment or an acceptance of a contract offer. Contract terms
>> contained in this telecommunication are subject to legal review and
>> the completion of formal documentation and are not binding until same
>> is confirmed in writing and has been signed by an authorized signatory.
>>
>
> _______________________________________________
> Bloat mailing list
> Bloat@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat
>
> _______________________________________________
> Bloat mailing list
> Bloat@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat

--
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
dave.collier-brown@indexexchange.com |              -- Mark Twain


CONFIDENTIALITY NOTICE AND DISCLAIMER : This telecommunication, including any and all attachments, contains confidential information intended only for the person(s) to whom it is addressed. Any dissemination, distribution, copying or disclosure is strictly prohibited and is not a waiver of confidentiality. If you have received this telecommunication in error, please notify the sender immediately by return electronic mail and delete the message from your inbox and deleted items folders. This telecommunication does not constitute an express or implied agreement to conduct transactions by electronic means, nor does it constitute a contract offer, a contract amendment or an acceptance of a contract offer. Contract terms contained in this telecommunication are subject to legal review and the completion of formal documentation and are not binding until same is confirmed in writing and has been signed by an authorized signatory.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: [Bloat] Hey, all, what about bandlength?
  2023-04-09 23:04         ` David Lang
  2023-04-10 11:04           ` Dave Collier-Brown
@ 2023-04-10 11:30           ` Sebastian Moeller
  1 sibling, 0 replies; 9+ messages in thread
From: Sebastian Moeller @ 2023-04-10 11:30 UTC (permalink / raw)
  To: David Lang; +Cc: Dave Collier-Brown, bloat

Hi Dave,


> On Apr 10, 2023, at 01:04, David Lang via Bloat <bloat@lists.bufferbloat.net> wrote:
> 
> TCP ramps up it's speed fairly slowly, and backs off fairly drastically when it is told (via ECN or a dropped packet) that it has hit the limit.

	[SM] That is the prevailing narrative, yes. However during slow start most/many TCPs double the congestion window every RTT and since it takes up to a full RTT for a drop or CE mark to be fed back to the sender, TCPs can end up with a congestion window that is up to twice as large as sustainable, so the "classic" halving of the congestion window when dropping out of slow-start seems not like a bad idea... after that the congestion window increase rate will be somewhat slower...


> As a result, a single TCP session is not going to fully utilize a connection.

	[SM] In my experience even single TCP flows can get close to saturation (but I typically do such tests over short paths...)


> There are people who do large, high speed transfers over long distances on a regular basis (think movie studios sending uncompressed movie footage around the world for processing).

	[SM] Yes, that is not me ;)


> To fully utilize their bandwidth, they use protocols that involve lots of connections operating in parallel

	[SM] Or stick to TCP but run a few connections in parallel, if these are not synchronized the aggregate ends up saturating a path pretty well (within reason, over long RTT paths the control loop simply is not as "tight" as over short RTT paths...)

Regards
	Sebastian


> 
> David Lang
> 
> On Sun, 9 Apr 2023, Dave Collier-Brown via Bloat wrote:
> 
>> Date: Sun, 9 Apr 2023 16:06:54 -0400
>> From: Dave Collier-Brown via Bloat <bloat@lists.bufferbloat.net>
>> Reply-To: Dave Collier-Brown <dave.collier-Brown@indexexchange.com>
>> To: bloat@lists.bufferbloat.net
>> Subject: Re: [Bloat] Hey, all, what about bandlength?
>> Consider a connection to my ISP as being an empty water-pipe, and I only want to measure the flow from the waterworks to me. In this case the waterworks is Rogers in Toronto, and the numbers come from me measuring the link with the Waveform bufferbloat tool.
>> 
>> The ISP promises me 1 Gbit/s of water.  OK, there is no such thing, but you get the idea (;-))
>> 
>> Let's consider the no-latency case.
>> 
>> *   The ISP turns on the tap, and it takes half an RTT to get to me, one way.  Let that be 1 millisecond, 0.001s of delay.
>> *   Once the delay is over, I get (1.0s - 0.001s) * 1 Gbit/s = 0.999 Gb/s. The 0.999 seconds is transfer time, and that transfer is at full speed of the pipe, so it adds up to 0.999 Gb/s
>> *   That's pretty good.
>> 
>> Now let's consider the best possible case where there is latency, but only one delay of 0.456s.  That basically means that only one transfer happens in the second, so there is only once change for latency to hurt me.
>> 
>> *   the one-way delay is still 0.001s, but there is also 0.231s of latency, for a delay of 0.232s
>> *   (1.0s - (0.001s + 0.231s) ) * 1 Gbit/s =
>> *   1.0s - 0.232s = 0.549s  * 1 Gbit/s = 0.768 GB/s
>> *   Cut by a quarter, by one packet's delay
>> 
>> What about the worst case?
>> 
>> *   It's not worst, but a pretty common case is a busy link with 1500-byte packets
>> *   One packet is 12,000 bits
>> *   In one second we can transfer 1,000,000,000 bits / 12,000bits/packet = 83,333.3 packets
>> *   Maybe that many delays, too?
>> *   Fortunately, no
>> 
>> I personally observed 456.2 Mbit/s, about 54% of a gigabit at home, so it's more like the latency cut my bandwidth in half
>> 
>> --dave
>> 
>> 
>> On 4/8/23 22:32, Michael Richardson via Bloat wrote:
>> 
>> 
>> Dave Collier-Brown <dave.collier-Brown@indexexchange.com><mailto:dave.collier-Brown@indexexchange.com> wrote:
>>  >> Dave Collier-Brown via Bloat<bloat@lists.bufferbloat.net><mailto:bloat@lists.bufferbloat.net> wrote: 
>>> 
>>  >> They he said "bandlength"
>>  >>
>>  >> > That sounded like an odd name, but the idea was cool:
>>  >>
>>  >> > If I have a bandwidth of 1 Mbit/S, but it takes 2 seconds to deliver
>>  >> 1 > Mbit, do I have a bandlength of only 1/2 Mbit/S?
>>  >>
>>  >> Is that because there is 2seconds of delay?
>> 
>>  > Well, 2 seconds elapsed time, 1 of which is delay.
>> 
>> Ah, would that include the delay to ask for the data?
>> (A DNS request, or an HTTP GET)
>> 
>> 
>> 
>> 
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^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2023-04-10 11:30 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-04-08 15:32 [Bloat] Hey, all, what about bandlength? Dave Collier-Brown
2023-04-08 18:49 ` Michael Richardson
2023-04-08 22:22   ` Jonathan Morton
2023-04-09  1:39   ` Dave Collier-Brown
2023-04-09  2:32     ` Michael Richardson
2023-04-09 20:06       ` Dave Collier-Brown
2023-04-09 23:04         ` David Lang
2023-04-10 11:04           ` Dave Collier-Brown
2023-04-10 11:30           ` Sebastian Moeller

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