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Re: a question... [9:2316] posted 12/18/2002
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If  interfaces on the unix machine belong to same segment, it is allowed to
give two ip address in the same subnet to the two different interfaces.
This connections can be used as load balancing. The restriction is that
gated or routed should not run on that unix machine.
If interfaces on the unix machine belongs to different LAN segments, this
type of configuration is not allowed.

The answer to your below question is that possibly any unix machine will
select the lowest numbered interface as gateway.
No load balancing will take in place.

Thanks ,


                      Sent by:                 Subject: Re: a question...

okie, lets take the OSPF out for a while......

if I have a "unix" machine with 2 NICs as my gateway for a network....

and both those NICs are in the same network...

and on each node/PC i configure the 2 IP addresses of each NIC as the

what is wrong with that.....fine, you may say "one NIC may be preferred for
traffic coming into this LAN"...but logically if the kernel code is fine,
should support NIC load balancing...right?

----- Original Message -----
From: fraanro
To: alok
Sent: Wednesday, December 18, 2002 10:14 PM
Subject: Re: a question... [9:2316]

> In theory, by definition, an IP router must have its interfaces in
> different IP subnets, because its mission is to route IP packets
> between different networks.
> I am not sure which may be the implication for a router to have two
> interfaces with one IP address each, but both belonging to the same
> subnet. From the routing table perspective it would have two entries of
> directly connected networks for the same subnet, wouldn't it?
> I do not see clear (unless used in different VRFs) how a router can see
> two interfaces on the same subnet.
> In the past I have configured in a Juniper two interfaces with IP
> addresses in the same subnet (even with the same IP) and it allows you
> to do it, but what I do not know is if both work, and how do they work
> (again, considering none of them is associated with a different vrf).
> Javier.
> ----- Mensaje Original -----
> Remitente: "alok"
> Fecha: Miircoles, Diciembre 18, 2002 3:02 pm
> Asunto: a question... [9:2316]
> > Hi All,
> >
> > is there anything wrong with having 2 ethernet interfaces in the same
> > network (OSPF running across the same to the other routers in the
> > networketc) with different IP addresses...?
> >
> > i know cisco doesnt let me assign the same IP network to 2 interfaces.
> >
> > unix does juniper..
> >
> > but what seems to be the problem in doing the same?
> >
> > -rgds
> > Alok
> >

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