Messages in this thread | | | Date | Wed, 24 Nov 2004 11:23:44 -0500 (EST) | From | linux-os <> | Subject | Re: Isolating two network processes on same machine |
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On Wed, 24 Nov 2004, Ole Laursen wrote:
> Hi, > > We need to test a peer-to-peer network application that is supposed to > be scalable. To that end, we have a FreeBSD box with dummynet and a > small cluster of Linux test machines. The box act as the gateway for > the test machines and delay incoming packets for a while before > throwing them back to the cluster to simulate latency on the Internet. > > By letting the test machines think they run on separate subnets, we > have been able to fool them into forwarding their packets to the > FreeBSD gateway even though everyone is connected to the same switch. > This is working fine. > > The problem is that we need to run several instances of our network > application on the same test machine since we have too few machines. > But when we create two IP addresses on the same machine with > > ifconfig eth0:0 10.0.0.2 netmask 255.255.255.0 broadcast 10.0.0.255 > ifconfig eth0:1 10.0.1.2 netmask 255.255.255.0 broadcast 10.0.1.255 > > and start two instances on the same machine with the two IP addresses, > then they communicate directly with each other instead of going > through the FreeBSD gateway. Can anyone see a way to solve this > problem? >
I was going to say, set the netmask small enough so that both machines are on different networks and set default routes to your gateway.... But there is a bug somewhere that doesn't allow a netmask of anything but 0 in the last byte.
So, just add a host route....
route add -host 10.0.1.2 gw server
> > (I've CC'ed the other guys in my group.) > > -- > Ole Laursen > http://www.cs.aau.dk/~olau/ > -
FYI, probably nobody will admit to it being a bug, but it's another example of policy spreading throughout the kernel. If I set the netmask to 0.0.0.0 or 255.255.255.255, and anything in-between, it should let me....
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