A method for a system comprising at least three network nodes (101, 102, 102) connected to each other by means of physical links (PH-1, PH-2, PH-3) forming a physical ring network, the method comprising: configuring a first virtual network connecting the same at least three network nodes of the physical ring network in the form of a chain (V1-1, V1-2) having two endpoints so that configuration of the first virtual network is static in nature but the configuration may be updated if a need arise, by storing to a network node that is an end point of the first virtual network an uplink next hop address or a downlink next hop address, and to each other network node between the end points a next hop address for uplink and a next hop address for downlink towards the network node the chain ends; and configuring a second virtual network connecting the same at least three network nodes of the physical ring that the first virtual network is connecting in the form of a chain (V2-1, V2-2) having two endpoints at least one of which is not common with the endpoints of the first virtual network so that configuration of the second virtual network is static in nature but the configuration may be updated if a need arise, by storing to a network node that is an end point of the second virtual network an uplink next hop address or a downlink next hop address, and to each other network node between the end points a next hop address for uplink and a next hop address for downlink towards the network node the chain ends; characterized by using the first virtual network and the second virtual network for transmitting correspondingly and substantially simultaneously a packet and a copy of the packet; the method further comprising: receiving, in a network node, a packet over one of the first virtual network and the second virtual network; checking (305, 306), whether the packet is targeted to the network node itself or to an apparatus served by the network node; and if not, forwarding the packet according to the configuration of the corresponding virtual network. configuring a first virtual network connecting the same at least three network nodes of the physical ring network in the form of a chain (V1-1, V1-2) having two endpoints so that configuration of the first virtual network is static in nature but the configuration may be updated if a need arise, by storing to a network node that is an end point of the first virtual network an uplink next hop address or a downlink next hop address, and to each other network node between the end points a next hop address for uplink and a next hop address for downlink towards the network node the chain ends; and configuring a second virtual network connecting the same at least three network nodes of the physical ring that the first virtual network is connecting in the form of a chain (V2-1, V2-2) having two endpoints at least one of which is not common with the endpoints of the first virtual network so that configuration of the second virtual network is static in nature but the configuration may be updated if a need arise, by storing to a network node that is an end point of the second virtual network an uplink next hop address or a downlink next hop address, and to each other network node between the end points a next hop address for uplink and a next hop address for downlink towards the network node the chain ends; characterized by using the first virtual network and the second virtual network for transmitting correspondingly and substantially simultaneously a packet and a copy of the packet; the method further comprising: receiving, in a network node, a packet over one of the first virtual network and the second virtual network; checking (305, 306), whether the packet is targeted to the network node itself or to an apparatus served by the network node; and if not, forwarding the packet according to the configuration of the corresponding virtual network. receiving, in a network node, a packet over one of the first virtual network and the second virtual network; checking (305, 306), whether the packet is targeted to the network node itself or to an apparatus served by the network node; and if not, forwarding the packet according to the configuration of the corresponding virtual network.