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RE: (ASCEND) second (Pipeline) router on a LAN
Thanks for your feedback.
We use NAT for upstream connection to our ISP, and use a segmented Class-C
network for our two offices.
We currently connect just fine to/from each office, and each office router
connects independently to the ISP. We now want to add a second router at
our main office to connect to the ISP (currently both the main and remote
office routers are serving double-duty to route one B-channel to the other
office and one B-channel to the ISP, and the load is too much). We seek /
plan to add a second router on LAN-1 to route just to the Internet.
I understand the IP subnetting for our two offices, and that part works
well right now. fyi -- we use 192.168.0.96 /27 for LAN-1 and 192.168.0.32
/27 for LAN-2. 192.168.0.126 is the gateway on LAN-1 and 192.168.0.62 is
the gateway on LAN-2.
The confusion for me is in the assignment of default gateways: it would
seem that I have to define ONE gateway on each machine. Clearly, a manual
routing table can be established on the NT Wks machines, but manual routing
tables are not "persistent" on the Win95 machines.
Also, I am not sure if I should invoke NAT on the "far" router (on LAN-2),
or just on the router connected out to the Internet.
Furthermore, I am unsure how to use static routing on the Pipeline 50. I
would appreciate step-by-step instructions on how to add a static route (we
have static routes to the other router on the ISDN - WAN connections).
ONE FINAL NOTE: On LAN-1, which will contain two routers (one to LAN-2 and
one to the ISP), which router should be setup as the gateway on the client
machines? I suppose it should be the router connected to LAN-2, and then
have that router define a default gateway (for traffic other than to the
subnet on LAN-2) to the other P-50 router ?
Thanks again for all the guidance !!
John Gill
Gill & Company, CPAs
www.taxlaws.com
----------
From: William T Wilson[SMTP:fluffy@dunadan.com]
Sent: Wednesday, March 18, 1998 12:38 AM
To: taxlaws.com@visi.net
Cc: ascend-users@bungi.com
Subject: Re: (ASCEND) second (Pipeline) router on a LAN
On Tue, 17 Mar 1998, Billy Matthews wrote:
> I have a small LAN with an Ascend ISDN Pipeline 50 router connected to
> an ISP, and am adding a second Pipeline router to connect to another
> office.
It all depends, in part, as to whether you are using NAT or not. This is
one of those rare cases where having NAT actually increases what you can
do with yourself.
Here's how I understand it:
<internet> -ISDN- P50 -ether- LAN -ether- P50 -ISDN- P50 -ether- LAN2
How you do this will be determined by how you have your IP's laid out.
Do you have NAT from your upstream provider, or regular IP addresses? If
you have regular IP's, you will have to get one for the P50 on the first
LAN, then (unless your upstream wants to give you another stack of IP's
for the other office) set up NAT on the P50 on the LAN-2, so that you have
that network using only 1 global IP.
If you have NAT, then you presumably are already using a subnet such as
10.0.0.0/8 or 192.168.0.0/16. You must split this net in half and give
half of your IP's to the "far" network. For example,
<internet> -P50- LAN(192.168.0.0/17) -P50- -P50- LAN2(192.168.128.0/17)
Now you have to assign the systems on the first LAN IP's in 192.168.0.0 to
192.168.127.255 and give them netmasks of 255.255.128.0. The systems on
the second LAN will now have IP's between 192.168.128.0 and
192.168.255.255. Now you must simply assign a static route on the P50's
connecting the two LAN's to route between these two halves of your NAT
assigned IP's. The farthest P50 in the chain will then set its default
route to the P50 on the other end of its ISDN link, and that P50 will
(like all the other hosts on that network) set its default route being the
P50 connected to the internet.
This is assuming that the second LAN only connects to the Internet by way
of the first LAN. You MIGHT have a situation such as the follows:
|------- INTERNET -------------|
P50 P50
\ /
LAN1 - P50 -ISDN- P50 - LAN2
In this case, if you are using NAT, you can set up your IP's as before.
Give one LAN 192.168.0.0/17 and the other LAN 192.168.128.0/17, and let
the P50's route between them, and the default routes go to the P50's
connected to the Internet.
Note that these solutions may require that that you renumber one or both
of these networks. There's not much that can be done about that,
If your LAN's are both NOT using NAT, then you will of course use whatever
IP's they have already, rather than the ones used in a typical NAT
install. The P50's can route between them statically, and traffic between
the LAN's will go over the one link, while traffic to/from the Internet in
each case will go over the normal Internet links. This is kind of a nice
setup because you get redundancy - any one of the links can go down
without destroying the ability to connect to any other site.
> connects outbound to the ISP. Static routing on each client is probably
> a bit difficult, since we run both Win 95 and NT Wks clients. I am not
Shouldn't make any difference. The systems on the ethernet should never
have to care what they use to connect to the rest of the world. That is
what routers do.
> sure how to setup routing on the Pipeline units, and RIP is really not
> attractive, since it seems to connect to the other office every 30
> seconds.
You don't need RIP for this. You can setup a call filter to block the RIP
broadcasts from bringing up the connection, but there's no need for
dynamic routing here, your setup is not complicated enough for it.
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