Abstract: Embodiments of the present invention provide a network label allocation method, a device, and a system, which enable a local PE to distinguish packets from different remote PEs. The method includes: generating, by a local provider edge PE, a VPN label route for each remote PE, where VPN labels in VPN label routes of different remote PEs are different, and the remote PE and the local PE at least belong to a same VPN; and sending the VPN label route to the remote PE, so that the remote PE separately matches an IP address of the remote PE with a target device IP address in the VPN label route, and matches an import route target RT of each VRF of the remote PE with a route target RT in the VPN label route, a packet related to a successfully matched VRF.

Abstract: A method and network device for distributing Multi-Protocol Label Switching (MPLS) labels are provided by the present invention. The method for distributing the MPLS labels includes: a first device receives a Border Gateway Protocol (BGP) protocol message transmitted from a second device, wherein the BGP protocol message carries a service identifier of the second device; the first device establishes, according to the service identifier of the first device and the service identifier of the second device, a corresponding relationship between the first device and the second device; the first device distributes a MPLS label for the corresponding relationship. The present invention realizes that the MPLS labels are distributed for some type of the specific logical relationship between the two nodes in the BGP protocol, so that the network devices running the BGP protocol can efficiently obtain the MPLS label corresponding to the specific logical relationship.

Abstract: A shell-and-tube heat exchanger includes a shell, heat transfer tubes, tube plates, covers, inlet and outlet for fluid flowing into and out of the shell, and inlet and outlet for fluid flowing into and out of the tubes, wherein the heat transfer tubes are corrugated heat transfer tubes, the tubing wall of the corrugated heat transfer tube is configured along the longitudinal direction of the corrugated heat transfer tube in a shape formed by tangentially connecting the crests of large arcs and the valleys of small arcs, the outside diameter D of the corrugated heat transfer tube is set at 1.3 to 1.5 times the inside diameter d, the corrugated heat transfer tubes are arranged spirally around the axis of the shell in multi-layers, and spiral plates are inserted between two layers of the corrugated heat transfer tubes.