See response below.

At 01:21 PM 11/14/01 -0800, Jeff Groetsema wrote:
>Ray,
>
>Here is the configuration I'm trying to work with.
>          Internet
>         _/
>        /
>    ________
>    |Router|
>    |______|
>       |
>       | Campus
>       | Backbone
>    ________
>    |Router|
>    |______|
>       _/
>      /  T1
>    ________
>    |Router|  x.x.150.254
>    |______|
>       |
>       | My Campus
>       | Backbone
>    ________
>    | LEAF |  x.x.150.253
>    |______|  x.x.153.254
>       |
>       |
>       |
>    ________
>    |laptop|  x.x.153.20
>    |______|
>             
>
>Even if Router 150.254 does not have routes for 153.0, shouldn't I still be
able to see hosts on My Campus Backbone from the laptop?

Short answer: NO. (Or, more exactly, YES as worded, but NO to the question
you mean to ask.)

Long answer: "see" is a meaningless word in this context. You need to think
about sending and receiving separately.

If you have a route *to* a host, you can send packets to it. If the host has
a route to you, it can send packets to you. So ... take the hypothetical
host x.x.150.42 on the "My Campus Backbone" network. 

You can send packets to it, because you know that the LEAF router is your
gateway, and the LEAF router knows how to reach network x.x.150.0/24 . 

But host x.x.150.42 itself either does or does not know that x.x.150.253 is
its route to x.x.153.0/24, and if it doesn't, then there is no way for
x.x.150.42 to send packets *directly* to hosts on that network. It will try
to send them to its default gateway, presumably also x.x.150.254 . So ...
the hypothetical x.x.150.42 -either- itself needs to know that route -OR-
its default gateway  needs to know the route. 

Connections to the Internet via the x.x.150.254 router have the same
problem. Either it knows that x.x.150.253 is its route to x.x.153.0/24 or it
doesn't. If it doesn't, then you won't be able to receive packets back from
the Internet. Similarly, other routers past this one also need to know their
routes to x.x.153.0/24 -- this is not something you can fix separate from
the rest of the Internet.

You really need to talk to your campus Network Administrator about this problem.


--
------------------------------------"Never tell me the odds!"---
Ray Olszewski                                        -- Han Solo
Palo Alto, CA                                    [EMAIL PROTECTED]        
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