On Fri Apr 05 2002 at 08:08, Morelli Enrico wrote:
> I have a PC running under RH7.2 with 2 ethernet cards. Is it possible to
> use both eths like if they were one to double network speed?
(You are not [theoretically] doubling network speed, but bandwidth.
There is a subtle but important difference).
> Thanks
Yes, you can do that, and a lot more besides. But how you do it
largely depends on what you want to achieve.
You can use something as elemental as the routing table, for example
something like this:
/sbin/ip route add default \
nexthop via 192.168.1.10 dev eth0 \
nexthop via 192.168.2.10 dev eth1
(assuming that the hosts at 192.168.{1,2}.10 are either the same box
at the other end, or two boxes with the same default gateway).
You can get more fancy with it and add weights and even specify a
specific src address for all local traffic going via this route
(source routing like this is recommended in many cases where you
are using nexthop routes).
(And you might even go more fancy again, like fwmark'ing packets
(eg, dst port 80 or 25) with ipchains/iptables and then use policy
routing to route different *types* of traffic (eg, web or mail)
via completely different default routes. And so on...).
/sbin/ip is a very powerful networking tool, it gives you almost
complete access to all of the advanced routing features of the 2.2.x
and 2.4.x kernels. (It makes /sbin/ifconfig and /sbin/route look
like the obselete historical dinosaurs that they are :)
Another method would be to use the teql device, which works by
"binding" two (or more, I've seen it done with 4/box) ethernet
interfaces to a teql0 device... you then route outgoing packets via
this device which then does the work of sending packets
alternatively via each of the devices that are bound to it. This
works particularly well on ppp dialup connections (although ppp
multilink is now a better alternative for doing that).
If you put twin/multiple crossover cables between two boxes, you can
do it in even more bizzare ways, like using identical IP addresses
on each of the local interfaces and munging the routing table with
"nexthop" directives so that it works as you expect.
Find the docs that come with the iproute2 package, and then do a
search for the advanced routing howto.
Cheers
Tony
