Re: 3 segment wireless network

On 22 May 2006 17:50:00 -0700, johnmclaren_99@xxxxxxxxx wrote:

chuck, i understand all of this; i'm not a noob.

there are no more than 7 computers in segment 2. there are 4 in
segment 3

i would say that no more than 2 computers would be accessing each other
at the same time, throughout the network, and there would probably be
no more than 5 computers on the internet at the same time... at the
most (worst case)

everything runs tcp/ip

John,

I know you're not a noob. But more detail might be useful here. And you keep
deleting my previous remarks, so I have to go back manually to review what I've
already said. This makes this whole process harder for me, and makes me make
mistakes, which is bad for you.

Let me describe a problem, greatly simplified (I can only type so fast).

You have 2 networks, connected by WiFi to a third network. Now since WiFi is a
shared medium, Computers A (on network A) and B (on network B) have to wait for
each other to finish, before sending anything to Router C (on network C).

This works OK for Internet transactions. Users on Computers A and B are surfing
the Internet asynchronously.
# User A sends a request for website D, to Router C. Computer B has to wait.
# While Router C is sending to Computer D (on the Internet), Computer B can send
a request for Website E, to Router C.
# Router C gets back a web page from Computer D, and sends it to Computer A.
Simultaneously, it's sending to Computer E (on the Internet).
# Router C gets back a web page from Computer E, and sends it to Computer B.
# Simultaneously, User A has requested web page F, and is waiting. As soon as
Computer B has web page E, Computer A is requesting web page F.
# And so on. This works for two reasons:
1) User A can be reading a web page while Computer B is requesting one.
Computers A and B are sharing the channel.
2) When Computer A is sending to Computer D, Computer D is upstream from Router
C, and connected by wired networks. Lots of wired networks. The WiFi link has
just 1 component: Computer A to Router C.

What happens if User A is getting a file from Computer B? A file will consist
of many packets of data, all coming from the other computer.
# Computer A sends a request to Computer B, thru Router C. Now you have a
request relayed by Router C, using WiFi BOTH WAYS. This is not too bad, though,
yet.
# Computer B sends back 1 packet of the file to Router C.
# Router C sends the packet to Computer A. Computer B has to wait before
sending a second packet.
# Uh oh. Computer A needs to send a thank you to Computer B, and ask for
another packet. The thank you goes from Computer A to Router C.
# Router C sends the thank you on to Computer B.
# Computer B sends the second packet to Router C.
# Router C sends the second packet on to Computer A.
# And so on. This is a slow process. Compared to the first example,
1) Computer B is sending to Computer A, supposedly continuously. No break in
the action, with a person viewing anything and making a decision.
2) When Computer B is sending to Computer A, Computer A is upstream from Router
C. The WiFi link has 2 components: Computer B to Router C, and Router C to
Computer A.

Now what happens if only Router C can see both Computers A and B? This is
called a hidden node problem. Since Computers A and B don't know each other is
there (on the channel), they keep sending simultaneously. Router C has to keep
telling one to shut up, when the other is sending, or keep dealing with the
problem of interference.
<http://en.wikipedia.org/wiki/Hidden_node_problem>
http://en.wikipedia.org/wiki/Hidden_node_problem

And add 3 more computers (you said a total of 5 accessing the Internet) while 2
are communicating with each other. All having to share that one WiFi channel.
Read about CSMA/CA please.

Now my apologies for writing stuff that you already know, but having only read 4
posts from you, I'm not sure what you do know and what you don't. You're asking
for help here, and I'm trying to help.

Anyway, after we get thru this problem, we'll get to the browser issue. And why
WiFi and the browser don't work well either.

--
Cheers,
Chuck, MS-MVP [Windows - Networking]
http://nitecruzr.blogspot.com/
Paranoia is not a problem, when it's a normal response from experience.
My email is AT DOT
actual address pchuck mvps org.
.

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