[nos-bbs] IP config for tun device

[George (Skip) VerDuin]

You are right on target with vocabulary Barry, mine has been sloppy.
Allow me to try to bring clarity?

On Tue, 2006-07-25 at 14:53 -0400, Barry Siegfried wrote:

> ["George (Skip) VerDuin" <k8rra at ameritech.net> wrote]:
> 

>SNIP<

> > Take tun configuration as a jnos example.
> >
> > Maiko and I had significant conversation a long time ago that resulted
> > in:
> >
> > [host ip 192.168.1.32]
> > [autoexec.nos]:
> > ip address 44.102.132.20
> > ifconfig tun0 address 192.168.2.1
> > shell ifconfig tun0 192.168.1.249 pointtopoint 192.168.2.1 ...]
> > adopted as a go-by for configuration.
> > It works just fine - it introduces two "new network identities".
> >
> > On the other hand tun may successfully be configured as:
> >
> > [host ip 192.168.1.32]
> > [autoexec.nos]:
> > ip address 44.102.132.20
> > ifconfig tun0 address 44.102.132.20
> > shell ifconfig tun0 192.168.1.32 pointtopoint 44.102.132.20 ...]
> > This configuration uses the "broader network identity" on each end of the tun device.
> > Both stacks do get the appropriate route configurations and ping works
> > fine.
> 
> Generally, if ICMP works, so will everything else that rides under
> IP.
> 

>SNIP<

> 
> The tun "device" is just like any other interface and can take on
> its own network "identity" with its own IP address.

OK - you are herein focused on the crux of my issue: When MUST (not "can
take on" as above) a separate "identity" be established?  

I can answer the obvious in the example when one host must support two
"telnet servers" and not having the option to use a special port#, then
two IPs must be established.  This is easy under unix-like platforms
with two stacks and tun connecting them.  Telnet #1 on the 192... net
from host platform and telnet #2 on the 44... net from jnos both using
the same port# solves that configuration.  Is it equally easy under the
DOS platform with one stack?  Now I suppose the server start command (or
config file) needs to specify the IP to service in order to make the
answer "yes"...  DOS is basically simpler because there is no need for
the tun device?

However the education I'm looking to acquire is not with the obvious -
and may be seen in the above example detail of tun configuration.  Above
I make the deductive observation that ping actually works under both
varieties of configuration.  But I'm working toward documentation of
jnos applications and deductive reasoning is not adequate - inductive
reasoning is.  My logic works a little like this:  Example 2 is cleaner
because ...2.1 IP in example 1 is a single node thus not really a
network, and ...1.249 of example 1 serves no obvious purpose for the
network.  (YES I know I used the work "obvious" and I'm not highly
qualified to)  Here I'm expecting that if I use example #2 in
documentation that tun may break for reasons I don't appreciate at this
moment and that would be poor quality workmanship on my part...

I like it a lot if the network design is so simple that one can say: 
  "When the IP, port #, socket, and application, are not ambiguous then
all is well in the network".
The alternative is to live long enough to have experienced a large
enough body of examples that work/fail?

> 

>SNIP<

> 
> Internetworking With TCP/IP
> Principles, Protocols and Architecture
> Copyright 1988
> 
> By Douglas Comer
> Department of Computer Sciences
> Purdue University
> West Lafayette, IN 47907
> 
> Published By Prentice Hall
> Englewood Cliffs, NJ 07632
> A Division of Simon & Schuster

The title sounds appropriate.  I've begun the search....  THANKS.

> 



73
de Skip k8rra k


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