Support for multiple virtual networks over an underlay network topology
Techniques are described for supporting multiple virtual networks over an underlay network. The techniques may provide support for network slicing and enhanced virtual private networks (VPNs) over an underlay network. In general, the techniques include allocating a subset of resources (e.g., nodes and/or links) of the underlay network to a particular virtual network, and advertising the subset of resources to provider edge (PE) routers that are participating in the virtual network. A network controller device may advertise the subset of resources for the virtual network to the respective PE routers using BGP-LS (Border Gateway Protocol-Link State). Based on the advertisements, each of the PE routers generates a restricted view of the full underlay network topology for the virtual network and, thus, only uses the subset of resources in the restricted view to generate routing and forwarding tables for the virtual network.
1. A controller device comprising:
a network interface; and
a control unit comprising at least one processor configured to:
allocate a subset of resources within an underlay network to each of one or more virtual networks established over the underlay network, wherein the subset of resources allocated to a respective virtual network includes one or more physical nodes and one or more physical links within the underlay network to be used by the respective virtual network, and
send advertisements of the subset of resources to a plurality of provider edge (PE) routers that are participating in the respective virtual network using one or more of a route target (RT) that identifies the respective virtual network, RT constraints, or route reflectors, wherein the advertisements of the subset of resources comprise a restricted view of the underlay network to indicate which resources within the underlay network are available to the plurality of PE routers to perform routing services for the respective virtual network.
2. The controller device of claim 1 , wherein, to send the advertisements, the at least one processor is configured to send Border Gateway Protocol-Link State (BGP-LS) advertisements of the subset of resources to the plurality of PE routers.
3. The controller device of claim 1 , wherein the at least one processor is configured to allocate the subset of resources to the respective virtual network based on source information, destination information, and classification information for traffic of the respective virtual network.
4. The controller device of claim 1 , wherein the at least one processor is configured to allocate the subset of resources to the respective virtual network with a PE router level of granularity.
5. The controller device of claim 1 , wherein the subset of resources allocated to the respective virtual network is one of dedicated to the respective virtual network or shared between the respective virtual network and at least one other virtual network.
6. The controller device of claim 1 , wherein the one or more virtual networks comprise one or more virtual private networks.
7. The controller device of claim 1 , wherein the one or more virtual networks comprise multiple network slices on top of the underlay network, wherein each of the multiple network slices is configured with different performance and scaling properties.
8. The controller device of claim 1 , wherein the underlay network comprises an Internet Protocol (IP) fabric of physical nodes and physical links.
9. The controller device of claim 1 , wherein the underlay network comprises a wide area network (WAN) that includes one or more autonomous systems.
10. A router comprising:
a plurality of network interfaces; and
a control unit comprising at least one processor configured to:
receive an advertisement of a subset of resources within an underlay network allocated to a virtual network in which the router is participating, wherein the subset of resources allocated to the virtual network includes one or more physical nodes and one or more physical links within the underlay network to be used by the virtual network,
generate a restricted view of the underlay network based on the advertisement, wherein to generate the restricted view of the underlay network, the at least one processor is configured to annotate a link state database of the router based on the subset of resources to indicate which resources within the underlay network are available to the router to perform routing services for the virtual network, and
perform routing services for the virtual network based on the restricted view of the underlay network.
11. The router of claim 10 , wherein, to perform routing services, the at least one processor is configured to generate a routing table and a forwarding table for the virtual network using only the subset of resources available in the restricted view of the underlay network.
12. The router of claim 10 , wherein, to receive the advertisement indicating the subset of resources, the at least one processor is configured to determine that the advertisement includes a route target (RT) that identifies the virtual network in which the router is participating.
13. The router of claim 10 , wherein, to receive the advertisement indicating the subset of resources, the at least one processor is configured to receive the advertisement from a route reflector that uses RT constraints.
14. A method comprising:
allocating, by a controller device, a subset of resources within an underlay network to each of one or more virtual networks established over the underlay network, wherein the subset of resources allocated to a respective virtual network includes one or more physical nodes and one or more physical links within the underlay network to be used by the respective virtual network; and
sending, by the controller device, advertisements of the subset of resources to a plurality of provider edge (PE) routers that are participating in the respective virtual network using one or more of a route target (RT) that identifies the respective virtual network, RT constraints, or route reflectors, wherein the advertisements of the subset of resources comprise a restricted view of the underlay network to indicate which resources within the underlay network are available to the plurality of PE routers to perform routing services for the respective virtual network.
15. The method of claim 14 , wherein sending the advertisements of the subset of resources comprises sending, by the controller device, Border Gateway Protocol-Link State (BGP-LS) advertisements of the subset of resources to the plurality of PE routers.
16. The method of claim 14 , further comprising:
receiving, by a respective PE router participating in the respective virtual network, an advertisement of the subset of resources within the underlay network allocated to the respective virtual network;
generating, by the respective PE router, the restricted view of the underlay network based on the advertisement to indicate the subset of resources within the underlay network that are available to the respective PE router to perform the routing services for the respective virtual network; and
performing, by the respective PE router, routing services for the respective virtual network based on the restricted view of the underlay network.
17. The method of claim 16 , wherein generating the restricted view of the underlay network comprises annotating, by the respective PE router, a link state database of the respective PE router based on the subset of resources in order to indicate which resources within the underlay network are available to the respective PE router to perform the routing services for the respective virtual network.
18. The method of claim 16 , wherein performing routing services comprises generating, by the respective PE router, a routing table and a forwarding table for the respective virtual network using only the subset of resources available in the restricted view of the underlay network.