On Sat, Aug 18, 2018 at 09:10:25PM +0200, Andrew Lunn wrote: > On Sat, Aug 18, 2018 at 01:39:50PM -0400, Robert P. J. Day wrote: > > > > (i'm sure this has been explained many times before, so a link > > covering this will almost certainly do just fine.) > > > > i want to loop one physical ethernet port into another, and just > > ping the daylights from one to the other for stress testing. my fedora > > laptop doesn't actually have two unused ethernet ports, so i just want > > to emulate this by slapping a couple startech USB/net adapters into > > two empty USB ports, setting this up, then doing it all over again > > monday morning on the actual target system, which does have multiple > > ethernet ports. > > > > so if someone can point me to the recipe, that would be great and > > you can stop reading. > > > > as far as my tentative solution goes, i assume i need to put at > > least one of the physical ports in a network namespace via "ip netns", > > then ping from the netns to the root namespace. or, going one step > > further, perhaps putting both interfaces into two new namespaces, and > > setting up forwarding. > > Namespaces is a good solution. Something like this should work: > > ip netns add namespace1 > ip netns add namespace2 > > ip link set eth1 netns namespace1 > ip link set eth2 netns namespace2 > > ip netns exec namespace1 \ > ip addr add 10.42.42.42/24 dev eth1 > > ip netns exec namespace1 \ > ip link set eth1 up > > ip netns exec namespace2 \ > ip addr add 10.42.42.24/24 dev eth2 > > ip netns exec namespace2 \ > ip link set eth2 up > > ip netns exec namespace1 \ > ping 10.42.42.24 > > You might also want to consider iperf3 for stress testing, depending > on the sort of stress you need.
FWIW I have a setup somewhere involving ip rule + ip route which achieves the same without involving namespaces. It's a bit hackish but sometimes convenient. I can dig if someone is interested. Regards, Willy
