Re: IP/Networking... 70-291.

There is no way I am going to be able to follow all that with numbers being
thrown around all over. Here is my diagram again with the Gateways
explained.

[Router #1]
|
|
|
|
[Router #2]--------<LAN 131.107.1.0/24>
|
|
<LAN 131.107.2.0/24
|
|
[Router #3]----------<LAN 131.107.25.0/24


Router #1
1. No way for me to know the Gateway of it. The Gateway of it will be
whatever Router is farther "outbound" from it which isn't part of the
Diagram.
2. It has a Static Route telling it to use Router #2 for the
131.107.0.0/16 segment

Router #2
1. This one uses Router #1 as the Gateway
2. This one has a Static Route telling it to use Router #3 for the
131.107.25.0/24 segment.

Router #3
1. This one uses Router #2 as the Gateway
2. <nothing>


--
Phillip Windell
www.wandtv.com

The views expressed, are my own and not those of my employer, or Microsoft,
or anyone else associated with me, including my cats.
-----------------------------------------------------

"Robert Bollinger" <RobertBollinger@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message news:7950FEF4-01FB-4C92-A900-76BFD89B535A@xxxxxxxxxxxxxxxx
SO here goes...

I assign... the following to my first router that i got from my t3
provier.
(Cisco 4700)

External Fully routable - 131.107.0.1
Subnet mask: 255.255.0.0
Gateway: My isps gateway for this network. say .254

Then i decide to assign this in my routers lan side for ethernet

131.107.5.1
255.255.255.0
What gateway goes here?

Then i decide to assign this in my routers lan side for eth/0
131.107.10.1
255.255.255.0
what gateway goes here?

I now understand what iw as doing wrong before. i was tryin to skip the
"router step" and was assigning 131.107.1.0/16 (system a) then
131.107.10.0/24 (system b).

they would not communicatie, so clearly i had that wrong.

In your scenario below, does router #2 have all the routes for that subent
and therefore does all of the "routing internally"?

if on my network i have 2 subnets 131.107.0.0/16 (default subnet) (which i
own) and then i subnet that to 131.107.1.0/24, when any machine on the
131.107.1.0/24 network communicates outside of its own network why the
"hosts
external to the /16" respond to the /16?

Pleaes advise...

Thank you,

Robert


"Phillip Windell" wrote:


"Robert Bollinger" <RobertBollinger@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message news:A0CA364B-6378-4ED4-B48A-16C7B366282E@xxxxxxxxxxxxxxxx
I am trying to understand that following information that comes from
the
70-291 book. this is on chapter 2-33 just above the figure 2.5.

It says this: if i have 131.107.0.0/16 ... that i can subnet that like
this:

131.107.1.0 /24 << Router A, 131.107.2.0 << Router B, 131.107.25.0 /24

This i understand just fine... however...

It then says... Hosts external to the orginization then access hosts
within
the orginization using the /16 address.

It is called SuperNetting.

[Router #1]
|
|
|
|
[Router #2]--------<LAN 131.107.1.0/24>
|
|
<LAN 131.107.2.0/24
|
|
[Router #3]----------<LAN 131.107.25.0/24

Since all three LANs "fit" inside of 131.107.0.0/16 the [Router #1] only
has
to know to send any thing contained within 131.107.0.0/16 to the [Router
#2]

The [Router #2] will already know what to do with it from that point.

So you are "SuperNetting" all three LANs into a single route between
[Router
#1] and [Router #2].

That is how the Internet works. Everything is SuperNetted. It doesn't
really "break down" until it gets between the ISPs and thier customers.
There are "billions" of routes on the Internet,...there is no way every
router on the Internet can maintain all that in a routing table,...so
everything is grouped together into a fewer number of routes containing
*huge* blocks of addresses. So the router only cares about which "next
hop"
router to send traffic where the destination is a member of one
particular
"huge block" of addresses. Once sent it doesn't worry about it after
that,...the next decision falls on the router that received it,...and the
process repeats over and over and over.

Think about it,...an IP Segment is not supposed to get over 250-300 hosts
because performance starts to suffer from the excessive broadcasts. That
is
covered by the /24 bit mask that gives 254 Hosts. So what are all the
other
lower bit masks for? They are for SuperNetting upstream of the final
destination to keep routing tables small and efficient. But when it
nears
the destination the IP Segments get broken down smaller and smaller until
they get down to 254 hosts or less (masks of /24 bits or higher)

--
Phillip Windell
www.wandtv.com

The views expressed, are my own and not those of my employer, or
Microsoft,
or anyone else associated with me, including my cats.
-----------------------------------------------------





.

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