Accessing Differents Subnets

Hello. My question isn't Linux specific, but I think you can help me. I
have a Linux box with one NIC. eth0 is configured with the IP
10.8.201.2 netmask 255.255.255.0. This box is connected to a router
whose IP is 10.8.201.1 and netmask is 255.255.255.0.

There is a box with the IP 10.8.201.34 and netmask 255.255.255.224
connected to another router. This router's IP is 10.8.201.33 and its
netmask is 255.255.255.224.

How can I access the box 10.8.201.34/27 from 10.8.201.2/24 ?? Is it
possible?



Thanks,
Gustavo

(E-Mail Removed) wrote:

> Hello. My question isn't Linux specific, but I think you can help me. I
> have a Linux box with one NIC. eth0 is configured with the IP
> 10.8.201.2 netmask 255.255.255.0. This box is connected to a router
> whose IP is 10.8.201.1 and netmask is 255.255.255.0.
>
> There is a box with the IP 10.8.201.34 and netmask 255.255.255.224
> connected to another router. This router's IP is 10.8.201.33 and its
> netmask is 255.255.255.224.
>
> How can I access the box 10.8.201.34/27 from 10.8.201.2/24 ?? Is it
> possible?
>
>
>
> Thanks,
> Gustavo
>
I am visual, so let me map this out in ASCII:


Network 1


+---------------+ +---------------+
|Host A | |Router A |
|10.8.201.2/24 |-------|10.8.201.1/24 |
+---------------+ +-------+-------+
| Network 2
+---------------+ +-------+-------+
|Host B | |Router B |
|10.8.201.34/27 +-------|10.8.201.33/27 |
+---------------+ +---------------+

Network 3

You setup the going between subnets on your routers. What type of
routers are you using?

--Scott

In article <(E-Mail Removed)>,
/dev/scott0 <(E-Mail Removed)> wrote:
>(E-Mail Removed) wrote:
>
>> How can I access the box 10.8.201.34/27 from 10.8.201.2/24 ?? Is it
>> possible?
>>
>I am visual, so let me map this out in ASCII:
>
> Network 1
>
> +---------------+ +---------------+
> |Host A | |Router A |
> |10.8.201.2/24 |-------|10.8.201.1/24 |
> +---------------+ +-------+-------+
> | Network 2
> +---------------+ +-------+-------+
> |Host B | |Router B |
> |10.8.201.34/27 +-------|10.8.201.33/27 |
> +---------------+ +---------------+
>
> Network 3

Routers within a single organization should not have overlapping subnets.
Host A thinks that Host B is on Network 1 and doesn't know about
Network 3. If Host A depends on broadcast traffic it can get confused.
For non-broadcast applications, this could be worked around by having
Router A do proxy ARP for addresses 10.8.201.32-63 and forwarding that
traffic to Router B.

The best solution is to define Network 1 as 10.8.201.0/27 on Router A
so there are no overlapping subnets and nobody has to do proxy ARP or
NAT. NAT would make Network 3 unavailable from Network 1 unless the
limited solution of port forwarding is set up on Router B.

On 2004-09-30, (E-Mail Removed) <(E-Mail Removed)> wrote:
> How can I access the box 10.8.201.34/27 from 10.8.201.2/24 ?? Is it
> possible?


hu... ping? If the two network are connected it should be possible
to communicate between them.

Davide

--
What you end up with, after running an operating system concept through
these many marketing coffee filters, is something not unlike plain hot
water.
-- Matt Welsh

Howard Johnson wrote:
> In article <(E-Mail Removed)>,
> /dev/scott0 <(E-Mail Removed)> wrote:
>
>>(E-Mail Removed) wrote:
>>
>>
>>>How can I access the box 10.8.201.34/27 from 10.8.201.2/24 ?? Is it
>>>possible?
>>>
> Routers within a single organization should not have overlapping subnets.
> Host A thinks that Host B is on Network 1 and doesn't know about
> Network 3. If Host A depends on broadcast traffic it can get confused.
> For non-broadcast applications, this could be worked around by having
> Router A do proxy ARP for addresses 10.8.201.32-63 and forwarding that
> traffic to Router B.
>
> The best solution is to define Network 1 as 10.8.201.0/27 on Router A
> so there are no overlapping subnets and nobody has to do proxy ARP or
> NAT. NAT would make Network 3 unavailable from Network 1 unless the
> limited solution of port forwarding is set up on Router B.


Mea Culpa. I must have been really tired when I drew that. And to think
I have been working on this kind of stuff in school for the past 4 weeks
:-(.

--Scott

(E-Mail Removed) wrote:

> Hello. My question isn't Linux specific, but I think you can help me. I
> have a Linux box with one NIC. eth0 is configured with the IP
> 10.8.201.2 netmask 255.255.255.0. This box is connected to a router
> whose IP is 10.8.201.1 and netmask is 255.255.255.0.
>
> There is a box with the IP 10.8.201.34 and netmask 255.255.255.224
> connected to another router. This router's IP is 10.8.201.33 and its
> netmask is 255.255.255.224.
>
> How can I access the box 10.8.201.34/27 from 10.8.201.2/24 ?? Is it
> possible?

Given that your computer will think the other computer is on the same
subnet, you'll have some configuraton issues. You might be able to create
a host route, for that one computer, via the other router. You'd then have
to configure the other router, to pass traffic to the appropriate computer.
In short, using the same subnet range for both, causes lots of problems.

--

(This space intentionally left blank)

Davide Bianchi wrote:

> On 2004-09-30, (E-Mail Removed) <(E-Mail Removed)> wrote:
>> How can I access the box 10.8.201.34/27 from 10.8.201.2/24 ?? Is it
>> possible?
>
>
> hu... ping? If the two network are connected it should be possible
> to communicate between them.

Check again. He's using overlapping subnet addresses. Any computer on the
first network will think many of the computers on the 2nd network are on
the same network.


--

(This space intentionally left blank)

Both routers are Cisco. I don't have access on the routers,
unfortunatelly. I'll talk with the guys who run the routers and I'll
try to convince them to change the subnet on Network 1.

It was not me who have set up the network. It is quite a mess, as you
guys can note. Thanks for your help.

Best Regards,
Gustavo