«

I was thinking about a pleasing feature of TCP/IP.

The throughput does not depend on how many hops it takes to get to
you. It depends on the speed of the slowest hop, which would normally
be the one next to you or next to the server. TCP/IP is like a very
long train of packets with many in flight at once. There is no fixed
path for packets.

A highspeed middle link could be the bottleneck if it were the most
congested.

On the other hand if you send a datagram and send a datagram in
return, the response time depends on the number of hops.

So even though the Internet is designed at the fundamental level
around delivery of individual packets, it is most efficient when
delivering streams.
--
Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

"Roedy Green" < > wrote in
message news:...
>I was thinking about a pleasing feature of TCP/IP.
>
> The throughput does not depend on how many hops it takes to get to
> you. It depends on the speed of the slowest hop, which would normally
> be the one next to you or next to the server. TCP/IP is like a very
> long train of packets with many in flight at once. There is no fixed
> path for packets.
>
> A highspeed middle link could be the bottleneck if it were the most
> congested.
>
> On the other hand if you send a datagram and send a datagram in
> return, the response time depends on the number of hops.
>
> So even though the Internet is designed at the fundamental level
> around delivery of individual packets, it is most efficient when
> delivering streams.


Yes - now come up with a way for me to explain to my grandma the difference
between latency and throughput - because thus far people just don't get it.

--
LTP

On Fri, 23 Dec 2005 15:50:08 -0700, "Luc The Perverse"
<> wrote, quoted or indirectly
quoted someone who said :

>Yes - now come up with a way for me to explain to my grandma the difference
>between latency and throughput - because thus far people just don't get it.

The difference between one guy with a bucket and a bucket brigade. The
bucket does not get there much faster by brigade, but more buckets per
minute do.
--
Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

"Roedy Green" < > wrote in
message news:...
> On Fri, 23 Dec 2005 15:50:08 -0700, "Luc The Perverse"
> <> wrote, quoted or indirectly
> quoted someone who said :
>
>>Yes - now come up with a way for me to explain to my grandma the
>>difference
>>between latency and throughput - because thus far people just don't get
>>it.
>
> The difference between one guy with a bucket and a bucket brigade. The
> bucket does not get there much faster by brigade, but more buckets per
> minute do.

Ah thanks - that works well.

--
LTP

Roedy Green wrote:
> On the other hand if you send a datagram and send a datagram in
> return, the response time depends on the number of hops.

Not really. Datagrams are routed the same way as TCP segments, so
consecutive datagrams can take different paths through the network, just
as TCP segments can.

Luc The Perverse wrote:

> Yes - now come up with a way for me to explain to my grandma the difference
> between latency and throughput - because thus far people just don't get it.

The difference between a truckload of tapes and a modem. The truck has
high bandwidth, long latency, the modem has low bandwidth, short latency.

"E.J. Pitt" <> wrote in message
news:UJ7sf.114266$...
> Luc The Perverse wrote:
>
>> Yes - now come up with a way for me to explain to my grandma the
>> difference between latency and throughput - because thus far people just
>> don't get it.
>
> The difference between a truckload of tapes and a modem. The truck has
> high bandwidth, long latency, the modem has low bandwidth, short latency.

While I appreciate your effort - I have more faith in the bucket brigade
idea Maybe it's just cause I know my grandma.

--
LTP

On Tue, 27 Dec 2005 08:26:24 GMT, "E.J. Pitt"
<> wrote, quoted or indirectly quoted
someone who said :

>> On the other hand if you send a datagram and send a datagram in
>> return, the response time depends on the number of hops.
>
>Not really. Datagrams are routed the same way as TCP segments, so
>consecutive datagrams can take different paths through the network, just
>as TCP segments can.

Even if each packet goes a different route, by slightly different
numbers of hops, the round trip time for the entire packet bundle
depends on the number of hops and the time of each hop, or more
precisely the case for the worst subpacket.


--
Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

On Tue, 27 Dec 2005 03:04:49 -0700, "Luc The Perverse"
<> wrote, quoted or indirectly
quoted someone who said :

>While I appreciate your effort - I have more faith in the bucket brigade
>idea Maybe it's just cause I know my grandma.

Why does Grandma want to know this?
--
Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

"Roedy Green" < > wrote in
message news:...
> On Tue, 27 Dec 2005 03:04:49 -0700, "Luc The Perverse"
> <> wrote, quoted or indirectly
> quoted someone who said :
>
>>While I appreciate your effort - I have more faith in the bucket brigade
>>idea Maybe it's just cause I know my grandma.
>
> Why does Grandma want to know this?


She doesn't - she was never interested, and that is likely why she just
couldn't grasp it.

It came up once a long time ago in a conversation with her.

The question has come up multiple times though; I remember once trying to
explain to a friend why a modem might be superior to a satelite connection
for playing games. I got through to him, but it was harder than I expected
it to be to explain. The concept seems intuitive to me, so it is my belief
that an example to which someone can relate should aid in making it
intuitive to other people.

--
LTP