Date: Thu, 26 Jul 2001 16:29:53 -0500 From: "Steven Ames" <steve@virtual-voodoo.com> To: "Jonathan M. Slivko" <jslivko@blinx.net>, "Chris Dillon" <cdillon@wolves.k12.mo.us>, <freebsd-hackers@FreeBSD.ORG> Subject: Re: Why two cards on the same segment... Message-ID: <015201c1161a$1fd46ae0$28d90c42@eservoffice.com> References: <Pine.BSF.4.32.0107261528390.2406-100000@mail.wolves.k12.mo.us> <001701c11614$94114000$6401a8c0@equinox> <00fa01c11615$73cccb10$28d90c42@eservoffice.com> <003401c11616$d2a8e460$6401a8c0@equinox> <011d01c11617$10b96950$28d90c42@eservoffice.com> <005f01c11618$145b04a0$6401a8c0@equinox>
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You lost me. How what is being done? You can use ifconfig to assign
as many blocks/netmasks as you feel the urge to. It'll do it.
How does it determine what source address to use? I'd be guessing on
this one but here's my guess:
1. If your communicating with a directly connected subnet then the OS
will use the IP address that's bound to the ethernet card that is
within that subnet;
2. If your communicating to a network that is not directly connected
then the OS will use (here's where I get guesswork though I plan
to test this when I leave work) either the main IP address (i.e. the
one that wasn't created as an 'alias') or the ip address bound to
the ethernet card that is in the same subnet as the next hop.
-Steve
> Then whats the alternative, it just works out of thin air? Now i'm really
> curious to find out how this is being done, although I have seen it done
on
> my own systems in the past, just not by me, so i'm intrigued to find out
how
> this is being accomplished. -- Jonathan
>
> --
> Jonathan M. Slivko <jslivko@blinx.net>
> Blinx Networks
> http://www.blinx.net/
>
>
> ----- Original Message -----
> From: "Steven Ames" <steve@virtual-voodoo.com>
> To: "Jonathan M. Slivko" <jslivko@blinx.net>; "Chris Dillon"
> <cdillon@wolves.k12.mo.us>; <freebsd-hackers@FreeBSD.ORG>
> Sent: Thursday, July 26, 2001 5:07 PM
> Subject: Re: Why two cards on the same segment...
>
>
> > Not really. The private IP space probably never leaves that LAN segment
so
> > the source IP would get set properly and the default route is
irrelevent.
> > Whenever
> > he communicated with a block that is not diretly attached then the code
> has
> > to
> > choose a source address and then send the packet to the next hop
(usually
> > the
> > default route unless you have a dynamic protocol daemon
(routed/gated/etc)
> > running. As long as your just communicating to directly attached subnets
> > everything
> > will work peachy regardless of public/private/quantity/netmask.
> >
> > -Steve
> >
> > > Yes, but what that snippet showed from ifconfig showed 2 networks, 2
> from
> > > public IP space and 1 from private IP space, and since it's working
the
> > > networking code must know/care about something that it's being fed. --
> > > Jonathan
> > >
> > > --
> > > Jonathan M. Slivko <jslivko@blinx.net>
> > > Blinx Networks
> > > http://www.blinx.net/
> > >
> > > ----- Original Message -----
> > > From: "Steven Ames" <steve@virtual-voodoo.com>
> > > To: "Jonathan M. Slivko" <jslivko@blinx.net>; "Chris Dillon"
> > > <cdillon@wolves.k12.mo.us>; <freebsd-hackers@FreeBSD.ORG>
> > > Sent: Thursday, July 26, 2001 4:56 PM
> > > Subject: Re: Why two cards on the same segment...
> > >
> > >
> > > > > Yes, but, I think the issue with the 2 IP classes working is
because
> > one
> > > > is
> > > > > not routable, and therefore it's not a real
> > > > > IP address, and the router knows this, hence it's not reacting to
> it
> > by
> > > > > stopping to work. As long as you use virtual
> > > > > ip's (192.168.*.*) then there should be no reason why it wouldn't
> > work.
> > > > > However, if your talking about a routable
> > > > > IP address, then you might have a problem, as there is a
difference
> > > > between
> > > > > a virtual IP address and a real (routable)
> > > > > IP address. Just my 0.02 cents. -- Jonathan
> > > >
> > > > I don't think the networking code knows/cares if something is
private
> or
> > > > public IP space. I might be off here but I think the real problem
with
> > > > two seperate networks on one card (or even on two cards) would be
> > > > the default route (can't have two right?) and which IP address gets
> > > > used as the 'source IP' on packets leaving the system.
> > > >
> > > > -Steve
> > > >
> > > >
> > > >
> > >
> >
> >
> >
>
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