As a bearer network technology for the Next Generation Network (NGN), the Ethernet technology is characterized by low cost, easy operation, and convenient upgrade. The Ethernet technology develops from single networks to a hierarchical and connection-oriented trend, and the current hierarchical Ethernet technology shapes up gradually. In the development process, a Provider Backbone Bridge Traffic Engineering (PBB TE) technology, namely, a Provider Backbone Transport (PBT) technology, is generated.
The PBB TE technology implements the connection-oriented feature of the Ethernet, and is a derivative technology of the Ethernet standard. It disables the spanning tree and disables the flood mechanism and the broadcast mechanism of traditional Ethernet, and provides various services by setting up tunnels on the backbone network. The PBB TE technology is developed on the basis of the Media Access Control (MAC)-in-MAC technology. The MAC-in-MAC technology uses the MAC address of an operator to encapsulate a user's MAC address, thus reducing and isolating user MAC addresses in the data transmission process. The MAC-in-MAC technology enables a network to be hierarchical, for example, divides a network into three layers, namely, a user network layer, a provider network layer, and a backbone network layer connected to each provider network. FIG. 1 schematically shows MAC-in-MAC network connections in the prior art. The network connections include a user network layer, a provider network layer, and a backbone network layer. Specifically, the user network layer is composed of a Customer Bridged Network (CBN) X and a CBN Y; the backbone network layer is a Provider Backbone Bridged Network (PBBN) layer; and the provider network layer is composed of Provider Bridged Network (PBN) X and PBN Y, where the PBN X connects the CBN X and the PBBN, and the PBN Y connects the CBN Y and the PBBN.
The PBB TE technology sets up a tunnel on the PBBN network to forward the two-layer MAC data frames. The tunnel is identified by a Backbone Destination Address (B-DA) and a Backbone Virtual Local Area Network ID (B-VID) in a B-tag. In the PBB TE tunnel, only the B-tag needs to be identified, and the user information is transparent. The PBB TE technology provides connection-oriented services for data frames, and sets up a working tunnel and a standby tunnel through an outer tag (B-tag)+B-DA (“+” means “plus”). The number of the standby tunnels to be set up depends on the actual network configuration. Each B-VID identifies the working tunnel and the standby tunnel between a Backbone Source Address (B-SA) and a Backbone Destination Address (B-DA). FIG. 2 schematically shows PBB TE tunnel connections in the prior art. The data frames are forwarded between the B-SA and the B-DA1 through the working tunnel identified by B-VID1, and the data frames are forwarded between the B-SA and the B-DA2 through the working tunnel identified by B-VID1, and a standby tunnel is configured for the working tunnel and is identified by B-VID2. The standby tunnel provides end-to-end protection for the working tunnel between the B-SA and the B-DA2. The data frames are forwarded between the B-SA and the B-DA3 through the working channel identified by B-VID1. On a PBBN network, the working tunnel between the B-SA and the B-DA1 is identified by B-DA1+B-VID1; the working tunnel between the B-SA and the B-DA2 is identified by B-DA2+B-VID1, and the standby tunnel is identified by B-DA2+B-VID2; and the tunnel between the B-SA and the B-DA3 is identified by B-DA3+B-VID1. In the PBB TE tunnel, the B-VID is reusable for different B-DAs, but it is necessary to ensure the combination of B-DA and B-VID, that is, the B-DA+B-VID to be unique throughout the PBBN. The PBB TE technology provides a good foundation for network expansion.
Normally, the data traffic (namely, data frames) sent from the B-SA runs along the working tunnel to the B-DA. When the working tunnel fails, the preconfigured standby tunnel becomes active and takes over the data traffic sent from the B-SA. The data traffic is sent to the B-DA through the standby tunnel to implement protection switching. The protection switching provides carrier grade end-to-end protection between the B-SA and the B-DA. FIG. 3 schematically shows PBB TE end-to-end protection in a prior art. When the working tunnel identified by B-VID1 between the B-SA and the B-DA2 fails, the B-SA switches the data frames over to the preconfigured standby tunnel identified by B-VID2. On the PBBN, the standby tunnel is identified by B-DA2+B-VID2, and the data frames are sent to the B-DA2 through the standby tunnel, thus implementing protection switching and PBB TE end-to-end protection.