Networking tuning in KVM

What I have seen in most KVM environment is that all the network traffic from a guest will take a single network path. There won't be any traffic segregation, which causes congestion in most KVM setups. As a first step for network tuning, I would advise trying different networks or dedicated networks for management, backups, or live migration. But when you have more than one network interface for your traffic, please try to avoid multiple network interfaces for the same network or segment. If this is at all in play, apply some network tuning that is common for such setups; for example, use arp_filter to prevent ARP Flux, an undesirable condition that can occur in both hosts and guests and is caused by the machine responding to ARP requests from more than one network interface:

echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter or edit /etc/sysctl.conf to make this setting persistent.

For more information on arp flux please refer to http://Linux-ip.net/html/ether...