IP Technical question

[David Hansen]

On 25 Jan 2009 at 12:24, Peter Tomlinson wrote:

> It simply works: I run 2 systems side by 
> side and they each get their own messages; another machine arrives (such 
> as a visitor arriving with a laptop), is plugged in, gets given a local 
> address by the router and somehow the messages for it get to it, so 
> there must be an extension field in the messages sent by, for example, a 
> web site.

The box [1] notes which "internal" computer requests something. When a 
reply to that request comes back the box sends that reply to the 
computer which requested it. If there are three computers then the 
"replies" are sent to the appropriate computer.

If a "reply" arrives which the box cannot relate to a request then what 
the box does depends on how it is set up. It may discard the "reply" or 
it may send it to one or more specially designated computers for them 
to try and work out what to do with it.


[1] I use that word deliberately, as that is what it appears to be to 
most people.


-- 
  David Hansen, Edinburgh 
 I will *always* explain revoked encryption keys, unless RIP prevents 
me   
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54