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From: Manuel Mollar <mm.LARTC@nisu.org>
To: lartc@vger.kernel.org
Subject: [LARTC] routing philosophy
Date: Mon, 31 Dec 2001 10:36:48 +0000	[thread overview]
Message-ID: <marc-lartc-100979516331695@msgid-missing> (raw)

Hi,

Some notes on routing philosophy with linux.
Suposse you have an IP on eth0, say A.B.C.D, and a default gateway A.B.C.E using:

ip ad ad A.B.C.D/24 dev eth0
ip rou ad default via A.B.C.E

All is OK and working.
Suposse now you define a routing table Test and do:

ip rou ad default via A.B.C.E table Test
ip rule add from A.B.C.D table Test
ip rou flu cac

All is still OK, then you put an INVALID default gateway A.B.C.Y (this IP is not a gateway, in fact it is no associated
to any computer):

ip rou del default
ip rou ad default via A.B.C.Y

Then, you telnet some_IP, IT WORKS as pakets are routed USING table Test. If you do:

ip rou get some_IP

it says:
some_IP via A.B.C.Y dev eth0 src A.B.C.D

Is this a correct response????
If you issue:

ip rou get some_IP from A.B.C.D

it says the coreect answer:
some_IP from A.B.C.D via A.B.C.E dev eth0

In fact if you do:
ip rou del default

then
telnet some_IP

it says:
Trying some_IP...
telnet: connect to address some_IP: Network is unreachable

but this is not true ... as default gw of main table is never used.
So it seems you have to stat some (even invalid) default gateway to achieve routing.
Any comment??



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             reply	other threads:[~2001-12-31 10:36 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-12-31 10:36 Manuel Mollar [this message]
2001-12-31 11:59 ` [LARTC] routing philosophy Jorge

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