Connecting multiple customer sites over a wide area network using an overlay network

摘要

A method and apparatus for connecting multiple customer sites over a wide area network (WAN) using an overlay network is described. In one embodiment of the invention, each one of multiple customer edge (CE) routers establishes a Border Gateway Protocol (BGP) session with one or more BGP route reflectors and announces their private IP network prefixes and one or more transport IP addresses to reach that CE router. The BGP route reflector(s) reflect those IP network prefixes and the one or more transport IP addresses to reach that specific CE router to the other CE routers. The CE routers receive those reflected IP network prefixes and the corresponding transport IP address(es) to reach that CE router in which those IP network prefixes belong and register them in their corresponding routing/forwarding data structures. In this way, the CE routers learn how to reach each other.

主权项

1. A method for connecting a plurality of customer sites over a wide area network (WAN) of a service provider, wherein each of the plurality of customer sites includes a customer edge router, the method comprising:
each of the customer edge routers establishing a Border Gateway Protocol (BGP) peer session with one or more route reflectors; each of the customer edge routers announcing the following to the one or more route reflectors:
one or more local routes that are local to the customer site in which that customer edge router belongs;one or more tunnel IP addresses of one or more interfaces of that customer edge router, wherein the one or more interfaces of that customer edge router respectively connect that customer edge router to a set of one or more provider edge routers in the WAN; anda preferred tunnel type and tunnel specific information to reach that customer edge router, wherein the tunnel specific information includes one or more of an encryption key and a password, and wherein the preferred tunnel type and tunnel specific information facilitate automatically setting up secure communication between that customer edge router and other customer edge routers; the one or more route reflectors reflecting the one or more local routes, one or more tunnel IP addresses, and the preferred tunnel type and tunnel specific information received from each of the customer edge routers to the other ones of the customer edge routers; each of the customer edge routers installing the following that is received from the one or more route reflectors from a particular customer edge router: the one or more local routes, the corresponding one or more tunnel IP addresses of one or more interfaces of that particular customer edge router for which those one or more local routes belong, and the preferred tunnel type and tunnel specific information to reach that particular customer edge router; a first customer edge router performing the following in response to receiving a first packet from a first customer device that corresponds to a first local route in a first one of the plurality of customer sites, wherein the first packet is destined for a second customer device that corresponds to a second local route in a second one of the plurality of customer sites:
determining that a second customer edge router provides reachability for the second local route,encapsulating the first packet within a second packet resulting in a first encapsulated packet for traversing the WAN of the service provider to reach the second customer edge router, wherein the second packet has a destination IP address that is one of the one or more tunnel IP addresses of one or more interfaces of the second customer edge router, and wherein the second packet has a source IP address that is one of the one or more tunnel IP addresses of one or more interfaces of the first customer edge router, andtransmitting the first encapsulated packet over the WAN of the service provider towards the second customer edge router for decapsulation and delivery to the second customer device; and the second customer edge router performing the following in response to receiving the first encapsulated packet:
decapsulating the first encapsulated packet to reveal the first packet,determining, from the first packet, that the second customer device is a destination of the first packet, andtransmitting the first packet towards the second customer device.