Re: TCP/IP Routing with Class B

[jbj1@bdsinc.com]

> 
> 
> I've got a new project and I need a refresher on TCP/IP to get it done.   
>  Can anybody help me with where I might find answers/documentation/sample   
> solutions, etc. on the following:
> 
> I have a company that wants to move to TCP/IP only.  They need to connect   
> to 3 locations and the Internet (4 routers).  The Internet link has a   
> firewall with Network Address Translation so we can use any addressing we   
> want internally.
> 
> We'd like to use a private class B address like 172.16.x.x internally for   
> the entire operation, but working with Class B's makes me go fuzzy on my   
> TCP/IP fundamentals.
> 
> Networks in each location would be 172.16.1.0,  172.16.2.0, 172.16.3.0,   
> and the Internet.  My questions are:

Not exactly. Such a numbering would imply that the three above networks
exist on the *same* physical net. If they were class C networks then they
would each be a different network. If you needed class B then your networks
would be numbered something like 172.16.0.0, 172.17.0.0, 172.18.0.0.

>  - What subnet mask(s) do we apply to the networks to get the routing to   
> work?

You don't really need a "subnet mask" to get it to work. Subnet masks are only
needed when you subdivide a network. If you have no more than 255 hosts
on each network, then choose 3 private class C networks, such as 192.168.0.0,
192.168.1.0, and 192.168.2.0. 

>  - With 4 routes to different subnets and the Internet, what routing   
> entries do we need to enter in the routers and the workstations?  Does a   
> routing protocol come into the picture?

You could use a routing protocol, but it isn't necessary. Absent of that though
you will need to make manual route additions on all boxes, e.g. for machines
in the 192.168.0.0 network, you'll need to add routes for the 192.168.1.0,
192.168.2.0 and internet. However, if for each network, one machine will be
the gateway to the other internal networks *and* to the internet router, you
can simply add a default route to each machine, ie. if on the 192.168.0.0
network, 192.168.0.1 is the gateway machine, then for all machines in the
192.168.0.0 network you simply need to do:

route add -net default gw 192.168.0.1

And likewise on the other nets.

--
Jens B. Jorgensen
jjorgens@bdsinc.com


--
TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to
debian-user-request@lists.debian.org . 
Trouble?  e-mail to templin@bucknell.edu .