Multiple Routers/Default: ISP & Pipeline 50 @ ISP

[emil...@my-dejanews.com]

We have several servers set up at a local ISP. Their default router is the
ISP's router. To access the servers remotely, we dial into an ISDN modem
which is connected to one of these machines. In order to free up the
machine, we would like to use an Ascend Pipeline 50 router.

Thus w/the Pipeline 50, we will be able to gain access to the servers.
However, what if we want communication that is initiated through ISDN to be
limited to ISDN? That is to say, I know that when I communicate to the
server it will be via the ISDN line, but when the server responds, how can I
make sure it will only go through the Pipeline 50 and now through the ISP
router that is set at default?

I'm very new at this, haven't set up a router before... so any advice or
direction is greatly appreciated.

Thanks!

em0QSADOiMoS

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[Laurence V. Marks]

In <6o0ekr$o29$1...@nnrp1.dejanews.com>, emil...@my-dejanews.com writes:
>We have several servers set up at a local ISP. Their default router is the
>ISP's router. To access the servers remotely, we dial into an ISDN modem
>which is connected to one of these machines. In order to free up the
>machine, we would like to use an Ascend Pipeline 50 router.
>
>Thus w/the Pipeline 50, we will be able to gain access to the servers.
>However, what if we want communication that is initiated through ISDN to be
>limited to ISDN? That is to say, I know that when I communicate to the
>server it will be via the ISDN line, but when the server responds, how can I
>make sure it will only go through the Pipeline 50 and now through the ISP
>router that is set at default?

Every TCP/IP setup has a file called a 'hosts' file, a configuration file read
by the 'route' program. Your server's file probably has one line in it,
something like
default <address of ISP's router>

You need to add another line to it which says
<Your home site's address> <netmask for your home site> <P50 IP Addr>

I may have these parameters in the wrong order. Most OSs (like OS/2 which I am
running here) have some real easy dialog boxes to fill out, so you don't have
to directly edit the hosts file.

Laurence V. Marks
IBM Corp. - Research Triangle Park, NC

[Kevin A. Smith]

emil...@my-dejanews.com wrote in message
<6o0ekr$o29$1...@nnrp1.dejanews.com>...

>We have several servers set up at a local ISP. Their default router is the
>ISP's router. To access the servers remotely, we dial into an ISDN modem
>which is connected to one of these machines. In order to free up the
>machine, we would like to use an Ascend Pipeline 50 router.

At both ends I assume?

>Thus w/the Pipeline 50, we will be able to gain access to the servers.

So the P50 will be in the same segment as the servers, and the ISP routers.

>However, what if we want communication that is initiated through ISDN to be
>limited to ISDN? That is to say, I know that when I communicate to the
>server it will be via the ISDN line, but when the server responds, how can
I
>make sure it will only go through the Pipeline 50 and now through the ISP
>router that is set at default?

Setup a static route on the servers that point to the P50 for your remote
network.
Alternatively, the ISP router could be setup with static routes to the P50,
if the
servers cannot be setup that way.

[Lee Ward]

As usual, Larry offers very good advice and info. There is another way
in this case that *may* be a bit easier. The Pipe 50 supports the RIP
dynamic routing update protocol. Enable it and set the "metric" to a low
value, like 1. If your servers aren't listening to RIP broadcasts, make
sure the routers are.

Basically, it's an automated method of doing what Larry describes. The
servers, if listening to RIP, will note the presence of the new router
and see that it's more efficient to send to them directly. If they don't
listen to RIP and the routers do, the routers will notice the new route
and send an ICMP redirect to the server telling it that there is a
better, more appropriate link.

The advantages are that when the ISDN link is not up the pipeline will
inform others and the ISP router(s) will be used if appropriate. Then,
new servers/routers won't have to be told about the pipeline, they'll
discover it. The disadvantage is that you may have to futz with the
router(s)/server(s) to allow RIP and, potentially, ICMP redirects.
You'll want to do it carefully -- as in you probably don't want the ISP
router(s) to propagate the route in this case. As well, if the local
network is not secure, an unauthorized host could broadcast bad routes
via RIP, hosing the router(s) tables. Routers can typically be told to
listen only to specific sources though. i.e. It can be made at least as
secure as Larry's solution.

Laurence V. Marks wrote:
>
> In <6o0ekr$o29$1...@nnrp1.dejanews.com>, emil...@my-dejanews.com writes:

> >We have several servers set up at a local ISP. Their default router is the
> >ISP's router. To access the servers remotely, we dial into an ISDN modem
> >which is connected to one of these machines. In order to free up the
> >machine, we would like to use an Ascend Pipeline 50 router.
> >

> >Thus w/the Pipeline 50, we will be able to gain access to the servers.

> >However, what if we want communication that is initiated through ISDN to be
> >limited to ISDN? That is to say, I know that when I communicate to the
> >server it will be via the ISDN line, but when the server responds, how can I
> >make sure it will only go through the Pipeline 50 and now through the ISP
> >router that is set at default?
>