Help! I need to configure static routes for Cisco 1721s

[brians]

OVERVIEW

This was dropped on me Friday:

I have two deployed teams of surveyors on board boats that are going to dial into my development network via INMARSAT. Their entry point into my network is a Cisco 2600 with 4 serial ports which appears to connect to some sort ISDN device that provides the serial signals. The calls come into a single number and PBX sends the call to the first available serial line.

NETWORK ADDRESSES

For this trial each of the nodes are subnetted off of a class C addresses (204.2.1.0 and 204.2.1.16 - mask 255.255.255.240) and connect to my class B network 175.31.0.0 (mask 255.255.0.0) via the 2600.

WHAT I NEED TO KNOW

What I understand about routing is what I've discovered from skimming through a basic guide on Cisco and reading posts on this web site this past weekend. I'd like to use static routing since this appears to be point-to-point application.

Do I need to assign a IP address to each of my serial lines on the 2600 or can I assign them the same IP address or even go IP unnumbered?

Do I need to assign IP addresses to the serial lines on the Cisco 1721 used by the survey teams?

I looked at using Bridging but I'm not sure it would work given the different network addresses.

Any help, tips, links and/or assistance you be GREATLY appreciated.

[Georg Pauwen]

Hello,

bridging is probably not a good option since it causes a lot of overhead. If I understand your setup correctly, your 1721 routers are used by the survey teams to connect to the 2600 ? I would assign IP addresses to the 1721 routers (the first available address of the subnet) and use static routes on your 2600, e.g.:

1721

!

interface Serial0

ip address 204.2.1.1 255.255.255.240

2600

!

ip route 204.2.1.0 255.255.255.240 204.2.1.1

or

ip route 204.2.1.0 255.255.255.240 SerialX (where X is the outgoing interface of your 2600 router).

Does this make sense ?

Regards,

GP

[brians]

Thank you GP for the quick reply. It appears from your post that I will need to assign my serial ports on my 2600 the same network address as the 1721s. Is that correct?

Do I make the FastEthernet Ports on the 1721s the default gateway for the 204.2.1.x subnets?