A method of transmitting packets in a computer network having a hierarchy of domains (102, 104, 106) individually having one or more network nodes interconnected with one or more end points, the hierarchy comprising a core domain at the highest level and at least two further lower levels containing at least two domains (104, 106) at each lower level, the method comprising: at a network node in a first domain of the at least two further lower levels of the hierarchy, receiving, from an originating end point of the first domain, a plurality of packets with corresponding end point identifiers individually having a value corresponding to an end point in a second domain of the at least two further lower levels of the hierarchy different than the first domain, wherein each level in the hierarchy is associated with a section of the end point identifiers, wherein an end point identifier has a plurality of sections arranged in a stack, and wherein a first section of each identifier has a value corresponding to the core domain; for each given packet, determining at least a portion of a network route from the network node to the end points in the second domain by performing a comparison of the value in the first section of the received end point identifier of a given packet with entries in a forwarding table in the network node, the forwarding table including entries specifying one or more network routes from the originating end point in the first domain to a destination end point in the same first domain, and an entry specifying a higher-level domain corresponding to all end points in the second domain; removing the first section of the received end point identifier of the given packet; and forwarding the packets to the higher-level domain based on the determined at least a portion of the network route. at a network node in a first domain of the at least two further lower levels of the hierarchy, receiving, from an originating end point of the first domain, a plurality of packets with corresponding end point identifiers individually having a value corresponding to an end point in a second domain of the at least two further lower levels of the hierarchy different than the first domain, wherein each level in the hierarchy is associated with a section of the end point identifiers, wherein an end point identifier has a plurality of sections arranged in a stack, and wherein a first section of each identifier has a value corresponding to the core domain; for each given packet, determining at least a portion of a network route from the network node to the end points in the second domain by performing a comparison of the value in the first section of the received end point identifier of a given packet with entries in a forwarding table in the network node, the forwarding table including entries specifying one or more network routes from the originating end point in the first domain to a destination end point in the same first domain, and an entry specifying a higher-level domain corresponding to all end points in the second domain; removing the first section of the received end point identifier of the given packet; and forwarding the packets to the higher-level domain based on the determined at least a portion of the network route.