Hi, I am trying to shape traffic to two VMs hosted in Xen. There seems to be very little information regarding this. I found this web page http://www.ioncannon.net/system-administration/57/limiting-bandwidth-usa ge-on-xen-linux-setup/ and followed the instructions. But, the real bandwidth experienced from clients always seems to exceed the set rate. Part of the problem may be because of the way Xen bridging is setup. There are many interfaces that the packets go through. So, I switched to the Xen routed networking, in which dom0 simply sees two virtual interfaces for the VM, which are kind of PPP connections to the eth0 interfaces in VM. eth0 +---- vif1.0 -- eth0 in VM1 | | +---- vif2.0 -- eth1 in VM2 Say, I want to limit the bandwidth to VM1 to 100mbit and VM2 to 500mbit (eth0 is a 1gbit interface), I used to following commands. iptables -t mangle -F POSTROUTING tc qdisc add dev eth0 root handle 1: htb r2q 1000 iptables -t mangle -A POSTROUTING -s $vm1_ip -j CLASSIFY --set-class 1:1 iptables -t mangle -A POSTROUTING -d $vm1_ip -j CLASSIFY --set-class 1:1 tc class add dev eth0 parent 1: classid 1:1 htb rate 512mbit iptables -t mangle -A POSTROUTING -s $vm2_ip -j CLASSIFY --set-class 1:2 iptables -t mangle -A POSTROUTING -d $vm2_ip -j CLASSIFY --set-class 1:2 tc class add dev eth0 parent 1: classid 1:2 htb rate 512mbit I setup a web server in VM1 and download a 1GB file from another machine that is on the same network (actually on the same enclosure). I always see wire speeds on the client side. I have tried many configurations including adding a sfq, pfifo, tbf class under the leaf classes, but either the rate becomes too low (because packets are dropped at the leaves) or too high. Part of the problem lies in the fact the vif1.0 has already received the traffice, so it has to be overlimited at eth0, instead of dropping. So, I tried a simple tbf within the VM. That doesn't work either with very low speeds. Xen VMs don't have very precise clocks, so that might be one reason why the reliable tbf is also not performing well. I also set the burst sizes manually and the speed again becomes exceptionally low. Please let me know if you have any ideas on why this is happening. I can paste the stats as well, if required. TIA, Pradeep _______________________________________________ LARTC mailing list LARTC@xxxxxxxxxxxxxxx http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
