Methods and apparatus for broadcast domain interworking

#The present application claims the benefit of the co-pending application Ser. No. 10/288,261, filed Nov. 5, 2002 having filed herewith, the entire disclosure of which is incorporated by reference as if set forth in its entirety herein.

#The invention relates generally to the interworking of customer edge devices in a heterogeneous network and, in particular, to the use of a centralized provider device for interworking customer edge devices.

#One application for multi-protocol label switching (MPLS) is the implementation of Layer 2 virtual private networks (VPN) using MPLS tunneling. Referring to FIG. 1, a typical wide area network (WAN) includes customer edge (CE) devices 100, 104, 108, and 112, and provider edge (PE) devices 116, 120 and 124. In general, an edge device is a device, e.g., a router, that sits on the edge of a network cloud such as the Internet or a private network. The customer edge devices connect a customer to a provider network using a data link technology, such as frame relay, while the provider edge devices reside on the edge of the provider network and aggregate connections from the customer sites. In many traditional configurations, the CE “devices” 100, 104, 108, and 112 are actually groups of homogeneous CE devices—i.e., multiple CE devices that are connected to their PE device using the same data link or data link type—that share the same edge of their connected PE device.

#The advantages of the invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings in which:

#FIG. 1 depicts a WAN having CE devices connected locally to their respective PE devices and remotely to other PE devices through a network cloud;

#FIG. 2 depicts a WAN having a centralized P device connecting CE devices on heterogeneous network branches in accord with the present invention;

#In the drawings, like reference characters generally refer to corresponding parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed on the principles and concepts of the invention.

#In brief overview, the present invention permits a P device in a heterogeneous network to learn the address information for its locally-connected CE devices by monitoring the control messages sent by the CE devices. In one embodiment, the P device shares this learned address information with its other locally-connected CE devices. Using this information, the P device transparently routes communications between CE devices that are connected to the P device using bridging and point-to-point links.

#FIG. 2 presents an embodiment of the present invention that utilizes a single P device 200 to bridge heterogeneously-connected local CE devices 204 and 208. The CE “devices” 204 and 208 may themselves be groups of homogeneous CE devices—i.e., multiple CE devices that are connected to the P device 200 using the same data link or data link type—that share the same edge of the P device 200. Local-area network (LAN) CE device 204 is connected to the P device 200 through gigabit Ethernet data link 212, which may or may not support VLAN tagging. WAN CE device 208 is connected to the P device 200 through frame relay data link 216 or, alternately, through another point-to-point data link like an ATM connection.