Brian,
I have used equal-cost multipath, and it works as advertised. once you
turn on the kernel option and build/install the new kernel, you can add
(in your case) two default routes. Linux will multiplex between them on
an IP-by-IP basis - in other words, each new destination IP address will
go out a different pipe. If you run all your traffic to one host, it will
all take one path. Still better than nothing!
As for making that work with IPFW or IPCHAINS and masquerading, I dunno.
That's an interesting question. I assume you will have different IP
addresses for the two cable modem interfaces. What you might want to do
is masq half your workstations behind one address and half behind the
other, that way you split it up somewhat. Not perfect, but again better
than nothing. You could split it service-by-service, but personally I'd
split the addresses instead.
Good luck, and let us know what happens. It's an interesting exercise!
Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
-- Isaac Asimov
On Mon, 30 Aug 1999, Brian Anderson wrote:
> On Mon, 30 Aug 1999, Andrew Chen wrote:
>
> > http://metalab.unc.edu/LDP/HOWTO/NET-3-HOWTO-6.html
> >
> > Section 6.2 in the trusty NET-3-HOWTO gives a pretty quick and
> > straightforward overview.
>
>
>
> Well, that deals with the eq1 serial line balancing, which would require
> support at the other end. since these are cable modems, and it's an
> ethernet based connection, that wouldn't work (if i'm following
> correctly)
>
> the part that keeps biting me is:
>
> "6.16 Routing in Linux-2.2
> The latest versions of Linux-2.1 offer a lot of flexibility in routing
> policy. Unfortunately, you have to wait for the next version of this
> howto, or go read the kernel sources. "
>
> I'm not quite cluefull enough to figure out from the sources what to do.
>
> the kernel options i'm looking at are:
>
> IP: equal cost multipath
> x Normally, the routing tables specify a single action to be taken in
> x a deterministic manner for a given packet. If you say Y here
> x however, it becomes possible to attach several actions to a packet
> x pattern, in effect specifying several alternative paths to travel
> x for those packets. The router considers all these paths to be of
> x equal "cost" and chooses one of them in a non-deterministic fashion
> x if a matching packet arrives.
>
>
> and
>
> x The header of every IP packet carries a TOS (Type of Service) value
> x with which the packet requests a certain treatment, e.g. low latency
> x (for interactive traffic), high throughput, or high reliability. If
> x you say Y here, you will be able to specify different routes for
> x packets with different TOS values.
>
>
>
> ideally, i'd like to alternate between 2 potential default routes...
> something where
>
> socket A -> eth0
> socket B -> eth1
> socket C -> eth0
>
> etc... so that a session gets opened on one device, and goes through
> completion, but then the next session would go on the second device. a
> round robin routing of sorts. with the added variable that the ISP side
> won't support any such configuration.
>
> am i looking at something totally unreasonable here?
>
> the ideal thing would be to have my firewall script load it's filters,
> masquerade traffic from eth2 on both eth0 and eth1, and then have some
> other rules determine where to send the packets. even if it had to be
> broken down that http would be on eth0, ftp on eth1... it would be
> something :)
>
>
> thanks,
> brian
>
>
> > Andrew
> >
> > On Mon, 30 Aug 1999, Brian Anderson wrote:
> >
> > >
> > > Can someone point me to a good document on using the Equal Cost Multipath
> > > kernel option? It sounds like what I'm looking for, but I haven't seen
> > > anything on how to actually set it up.
> > >
> > > Here's the situation: I have a Linux system, running 2.2.11, being used as
> > > a gateway/router machine for a 10 system network, internet connectio via
> > > cable modem, lan using 192.168.2.0/24. We are getting a second cable
> > > modem, and I'd like to try to set up some load sharing. Add a 3rd NIC to
> > > the Linux box, and set it up to alternate between connections.
> > >
> > > The LAN would be unchanged, the packets would get sent out to eth2 on the
> > > Linux system, and forwarded over eth0 or eth1...
> > >
> > > Any help would be really appreciated. The 2nd modem gos in on Wednesday,
> > > and I'd like to have this ready to go by then.
> > >
> > >
> > >
> > > brian
> > >
> > > -
> > > To unsubscribe from this list: send the line "unsubscribe linux-net" in
> > > the body of a message to [EMAIL PROTECTED]
> > >
> >
>
> --
>
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> going to sleep
> would be really nice right now
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>
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-- Isaac Asimov
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