...
virsh net-define virbr1.xml virsh net-start virbr1virsh net-autostart virbr1
[root@hp8300 vmx]# virsh help | grep net-
net-autostart autostart a network
net-create create a network from an XML file
net-define define an inactive persistent virtual network or modify an existing persistent one from an XML file
net-destroy destroy (stop) a network
net-dhcp-leases print lease info for a given network
net-dumpxml network information in XML
net-edit edit XML configuration for a network
net-event Network Events
net-info network information
net-list list networks
net-name convert a network UUID to network name
net-start start a (previously defined) inactive network
net-undefine undefine a persistent network
net-update update parts of an existing network's configuration
net-uuid convert a network name to network UUID