Re: Considerations about multilink conection under the same IP subnet [SOLVED?]

From: ArcosCom Linux User
Date: Tue May 27 2008 - 12:24:31 EST


Appears that the solution is:
1) Ignore ARP in the public interfaces (to allow the same IP under
diferents interfaces with diferents MACs).
2) Use the "hops" without "via".
3) Correct the rules that takes the routing decision using the IP, not
the subnet (as before).

Regards

El Mar, 27 de Mayo de 2008, 16:04, ArcosCom Linux User escribió:
> Hi, I'm having a problem and need some help to solve it.
>
> I have 2 uplink ADSL routers that allow me to connect my lan to internet.
> Call them ADSL0 and ADSL1. They have the same IP, call it IP_GW.
>
> I have to configure 2 IP in my linux router under the same IP subnet as
> IP_GW, call them PUB_IP0 and PUB_IP1.
>
> The conection is (more or less):
>
> LAN -- (eth0) LINUX ROUTER (eth1) -- ADSL0 --- INTERNET
> (eth2) -- ADSL1 ----|
>
> The problem is that ADSL0 and ADSL1 have the same IP and I have to say to
> my linux router that balance between them.
>
> I read LARTC and stand fine how to balance the conection when the ADSL0
> and ADSL1 (and PUB_IP0 and PUB_IP1) are in diferent IP subnets (two route
> tables, using marks to allow the feedback in the same interface and so
> on), but I need some help to apply the same concepts in this case.
>
> The questions I have are:
> a) How can I configure the linux box to allow ADSL0 and ADSL1 don't
> fight with ARP? (This question is because I think that 1 IP with 2 MACs
> under diferent interfaces can have a serious conflict). I think that I
> must change some /proc/sys/net/.../ files, but a don't know what files
> I have to change.
> b) What filters rules I have to put to disallow any type of confusion
> in the routing table? I have the "nexthops" using the same $IP_GW with
> with the "dev" explicitily writen in the default table as this:
>
> === REGLAS DE ENRUTAMIENTO ===
> 0: from all lookup local
> 50: from all lookup main
> 100: from all fwmark 0x8000/0xf000 lookup uno
> 101: from all fwmark 0x4000/0xf000 lookup dos
> 150: from PUB_SUBNET lookup uno
> 151: from PUB_SUBNET lookup dos
> 200: from all lookup defecto
> 32766: from all lookup main
> 32767: from all lookup default
> === TABLAS DE RUTAS ===
> === MAIN ===
> PUB_SUBNET dev eth1 proto kernel scope link src PUB_IP0
> PUB_SUBNET dev eth2 proto kernel scope link src PUB_IP1
> 192.168.3.0/24 dev zlan0 proto kernel scope link src 192.168.3.247
> 192.168.2.0/24 dev zlan0 proto kernel scope link src 192.168.2.247
> 192.168.1.0/24 dev zlan0 proto kernel scope link src 192.168.1.247
> 10.1.1.0/24 dev zlan0 proto kernel scope link src 10.1.1.6
> 169.254.0.0/16 dev zlan0 scope link
> === eth1 TABLA 150 ===
> default via IP_GW dev eth1 proto static src PUB_IP0
> prohibit default proto static metric 1
> === eth2 TABLA 151 ===
> default via IP_GW dev eth1 proto static src PUB_IP1
> prohibit default proto static metric 1
> === TABLA 200 (defecto) ===
> default via IP_GW dev eth1 nexthop via IP_GW dev eth2
>
> Any help/suggestion about this problem?
>
> Thanks
>
> P.D.: Sorry for my English.
>
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