The answer is pretty simple. You cannot have multiple default gateways.
That is why your connection disrupts if you bring up the private interface.
The default gateway address is needed to access any network or subnet
which your machine does not know (routing table). So if you have several
interfaces with their IP and subnets, it can talk to those by default.
You can route to different subnets on different interfaces via gw
information in the routing table. BUT(!), only one address can be the
_default _gateway. The default gw IP is used to access public networks,
or in other words, all IPs/subnets/networks your machine doesn't have in
the routing table.
Leave the default gw IP from your public interfaces. Remove the default
gw information from your private interface.
Let us know how it goes.
Cheers,
Rocco
On 23/02/2011 11:19 AM, Richard Zulu wrote:
Well,
The internal interface has a private I.P address, with a default
gateway of something like 172.16.0.1 and a subnet of /16
The external interfaces have Public I.Ps, with their default gateway
having public I.P.
@Collins, with the internal interface up, the internal interface has
it's default route pointing to it's default gateway, 172.16.0.1
And the external interfaces also points to their own default gateway.
On Wed, Feb 23, 2011 at 2:52 AM, sanga collins
<[email protected] <mailto:[email protected]>> wrote:
what is your default route when the internal interface is up?
On Tue, Feb 22, 2011 at 5:19 AM, Richard Zulu <[email protected]
<mailto:[email protected]>> wrote:
Hi,
Quick question: I have a linux box with three interfaces, two
of them face my external network (one is a sub-interface) ,
with the same gateway address but obviously different I.Ps.
Both are in the same public network / subnet
One of the interfaces faces my internal network, private IP
addresses.
Problem: With all the interfaces up, I cannot reach any of the
networks, both internal and external.
However, with the internal network interface down, I can get
to the external network.
I need my internal interface up so that I can get to my
internal network and at the same time get to the external
networks.
How can I pull it off?
--
Richard Zulu
gtug lead, Kampala (Uganda)
http://kampala.gtugs.org
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Sanga M. Collins
Network Engineering
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gtug lead, Kampala (Uganda)
http://kampala.gtugs.org
_______________________________________________
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_______________________________________________
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