Each of the autonomous networks 310, 330, and 350 utilizes an Interior Gateway Protocol (IGP) to route data within the autonomous network. For example, an Open Shortest Path First (OSPF) protocol may be used by each autonomous network 310, 330, and 350 as the IGP, but the present invention is not limited thereto. Within each autonomous network 310, 330, and 350 IGP routing information is distributed to all the nodes in the respective autonomous network 310, 330, or 350. The IGP routing information of a given autonomous network 310, 330, or 350 is stored in a routing table in each node of the respective autonomous network 310, 330, or 350. Using this IGP routing information, any node in an autonomous network 310, 330, or 350 can select an optimal path to any other node within that autonomous network 310, 330, or 350.
Each autonomous network 310, 330, and 350 can also use Multiprotocol Label Switching (MPLS) label distribution protocol to assign labels to its IGP routes. When using MPLS, the header information of an incoming data packet is analyzed by an autonomous network ingress provider edge (PE) which imposes a label header into the data packet. A label is assigned to the data packet based on a destination address field of the header information, and the data packet is routed across the autonomous network 310, 330, or 350 based on the label. Label distribution protocol information is distributed between the nodes in an autonomous network 310, 330, or 350. Commonly used label distribution protocols include the Label Distribution Protocol (LDP) and the RSVP protocol. A label distribution protocol distributes to every node in an autonomous network 310, 330, or 350 label binding information to each route in its IGP routing table. The label binding information of a label to an IGP route is of local significance to a node. Label binding information is stored in MPLS forwarding tables at the nodes and specifies how to switch a data packet from an incoming interface to an outgoing interface of the node based on the label header of the incoming data packet. At subsequent nodes (i.e., hops) within an autonomous network 310, 330, or 350, the label of a data packet is swapped and the data packet is forwarded using the MPLS forwarding tables stored at the nodes in the autonomous network 310, 330, or 350.
In the global IP network 300 according to the present invention, IGP routing data is also distributed between the autonomous networks 310, 330, and 350. The IGP routing information is distributed from each autonomous network 310, 330, and 350 into neighboring autonomous networks 310, 330 and 350 via the ASBRs 312, 314, 316, 332, 334, 336, 338, 340, 352, 354, and 356. The IGP routing information that is distributed between the autonomous networks 310, 330, and 350 includes location information for the PEs 318, 320, 340, 358, and 360 of the autonomous networks 310, 330, and 350. The location information of the PEs 318, 320, 340, 358, and 360 can include a loopback interface address of each PE 318, 320, 340, 358, and 360. This IGP information is distributed to all nodes including the PEs 318, 320, 340, 358, and 360 of each autonomous network 310, 330, and 350, so that each PE 318, 320, 340, 358, and 360 is aware of the PEs 318, 320, 340, 358, and 360 in other autonomous networks 310, 330, and 350. Accordingly, a PE 318, 320, 340, 358, or 360 can calculate an optimal path to any other PE 318, 320, 340, 358, or 360 in the global IP network 300. The label binding information is also distributed between the autonomous networks 310, 330, and 350 via the ASBRs 312, 314, 316, 332, 334, 336, 338, 340, 352, 354, and 356. This allows MLPS to be utilized when routing packets between autonomous networks 310, 330, and 350.
When IGP and label binding information of an autonomous network 310, 330, or 350 is distributed into a neighboring autonomous network 310, 330, or 350, the neighboring autonomous network 310, 330, or 350 can re-distribute that IGP and label binding information into yet another autonomous network 310, 330, or 350, that neighbors the neighboring autonomous network 310, 330, or 350. For example, when the IGP and label binding information of the AP autonomous network 310 is distributed from ASBR 312 and ASBR 314 into the USA autonomous network 330 via ASBR 332 and ASBR 334, respectively, the IGP and label binding information of the AP autonomous network 310 can be redistributed from ASBR 336 and ASBR 338 into the EMEA autonomous network 350 via ASBR 352 and ASBR 354, respectively. Thus, when routing a data packet to a PE 318 or 320 of the AP autonomous network 310, a PE 358 or 360 of the EMEA autonomous network 350 can consider a route through the USA autonomous network 330. The IGP and label binding information of the AP autonomous network 310 is also distributed from ASBR 316 into the EMEA autonomous network 350 through ASBR 356, so the PE 358 or 360 of the EMEA autonomous can select the optimum route among all possible routes to the PE 318 or 320 of the AP autonomous network 310.
It is also possible that an autonomous network 310, 330, or 350 be configured not to re-distribute IGP and label binding information of a neighboring autonomous network 310, 330, or 350 to another neighboring network. For example, the AP autonomous network 310 can be configured not to re-distribute the IGP and label binding information of the EMEA autonomous network 350 to the USA autonomous network 310. In this case, when routing a data packet to a PE 358 or 360 of the EMEA autonomous network 350, a PE 340 of the USA autonomous network 330 does not consider paths through the AP autonomous network 310. This may be desirable when the infrastructure of one autonomous network 310, 330, or 350, is not capable of handling traffic demands of network traffic transmitted from another autonomous network 310, 330, or 350.
As illustrated, in
At step 510, an ingress node of a first autonomous network receives a data packet. In
At step 520, the ingress node determines the location of the egress node of a second autonomous network using eBGP information exchanged between route reflectors 418 and 440 of the first and second autonomous networks 410 and 430. PE 412 uses the eBGP information exchanged between the first and second autonomous networks 410 and 430 to determine that PE 432 is the egress node which connects to CE 452. That is, based on the destination IP address in the header of the data packet, PE 412 uses the eBGP information to determine that the next hop to the destination IP address is the loopback interface address of PE 432.
At step 530, the ingress node selects a route from the ingress node to the egress node using IGP information of the second autonomous network distributed into the first autonomous network. For example, in
At step 540, the ingress node of the first autonomous network transmits the data packet along the selected route. PE 412 transmits the data packet to a first of sequential hops along the selected optimal route between PE 412 and PE 432. If the global IP network 400 utilizes MLPS, PE 412 analyzes the header of the data packet and uses distributed label binding information of the first and second autonomous networks 410 and 430 to assign a label to the data packet corresponding to the selected optimum route. The data packet is routed along the selected route based on the assigned label until the data packet reaches PE 432. When PE 432 receives the data packet, PE 432 transmits the data packet to CE 452.
The above described method can be implemented as a computer program executed by a device which functions as a router in an autonomous network. For example, the method may be implemented on a computer using well known computer processors, memory units, storage devices, computer software, and other components. A high level block diagram of such a computer is illustrated in
In addition to providing optimal routing across multiple autonomous networks, the present invention also can preserve transparency of Quality of Service (QoS) classifications in Managed Internet Service (MIS) service data packets transmitted across multiple networks. MIS service data packets in traditional intra-provider multiple autonomous networks are transmitted as unlabeled packets over the links interconnecting the autonomous networks. Transmitting these data packets as unlabeled packets exposes the customer Quality of Service (QoS) markings. Without altering customer markings to provide all customers' traffic the same QoS treatment, some customers' data packets may receive preferential QoS treatment at the expense of other customers' traffic. Because label binding information is distributed between autonomous networks, MIS service data packets are transmitted as labeled packets over the links between autonomous networks without altering the customer QoS markings. Thus, end-to-end QoS transparency can be preserved between provider edges of separate autonomous networks.
Furthermore, since the data packets can be routed over multiple autonomous networks based on labels instead of analyzing the IPv6 header information at hops in each network, autonomous system border routers (ASBRs) interconnecting the autonomous networks need not be IPv6-aware.
Also, because a provider edge of an autonomous network is aware of provider edges of other autonomous networks in the present invention, a provider edge can recognize a provider edge in another autonomous network as an exit point from a global network instead of only being able to recognize an ASBR in the same autonomous network as an exit point. Accordingly, the present invention can provide emerging technologies, such as Ethernet over MPLS (EOMPLS) and Virtual Private Line Service (VLPS) with the same support for inter-region and intra-region services.
The foregoing Detailed Description is to be understood as being in every respect illustrative and exemplary, but not restrictive, and the scope of the invention disclosed herein is not to be determined from the Detailed Description, but rather from the claims as interpreted according to the full breadth permitted by the patent laws. It is to be understood that the embodiments shown and described herein are only illustrative of the principles of the present invention and that various modifications may be implemented by those skilled in the art without departing from the scope and spirit of the invention. Those skilled in the art could implement various other feature combinations without departing from the scope and spirit of the invention.