Virtual L2TP/VPN tunnel network and spanning tree-based method for discovery of L2TP/VPN tunnels and other layer-2 services

• US 6,765,881 B1
• Filed: 12/06/2000
• Issued: 07/20/2004
• Est. Priority Date: 12/06/2000
• Status: Expired due to Term

• Current Assignee: GC Pivotal LLC (GTT Communications, Inc.)
• Original Assignee: Covad Communications Group Incorporated
• Inventors: Rajakarunanayake, Yasantha N.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US09/732,173
• Time in Patent Office: 1,322 Days
• Field of Search: 370/254, 370/255, 370/256, 370/338, 370/392, 370/389, 370/474, 709/224
• US Class Current: 370/256
• CPC Class Codes: H04L 12/4641 Virtual LANs, VLANs, e.g. virtual private networks [VPN] LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272
• CPC Class Codes: H04L 63/0272 Virtual private networks
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload

Abstract

A virtual L2TP/VPN tunnel network as well as a system and method for automatic discovery of VPN tunnels, such as L2TP tunnels, and other layer-2 services using a method such as one based on the spanning tree protocol are disclosed. The method for automatic discovery of layer-2 services across a network of layer-2 devices generally comprises transmitting an advertisement message on each tunnel of each layer-2 device, the advertisement message containing information for generating a spanning tree based on spanning tree algorithm, receiving advertisement message on the tunnels of each layer-2 device, and processing the received advertisement messages to generate a spanning tree topology of the network of layer-2 devices whereby each layer-2 device in the network automatically discovers layer-2 services of other layer-2 devices on the network. The transmitting is preferably repeated at predetermined configurable intervals.

Claims

1. A method for automatic discovery of layer-2 services across a network of layer-2 devices, comprising:

transmitting an advertisement message on each tunnel in communication with each layer-2 device, the advertisement message containing information for generating a spanning tree based on spanning tree algorithm;

receiving advertisement message via the tunnels in communication of each layer-2 device; and

processing the received advertisement messages to generate a spanning tree topology of the network of layer-2 devices whereby each layer-2 device in the network automatically discovers layer-2 services of other layer-2 devices on the network.

2. The method for automatic discovery of layer-2 services of claim 1, wherein the spanning tree comprises:

a root device selected form the network of layer-2 devices, each tunnel in communication with the root device being a designated tunnel on which advertisement messages are transmitted;

a root tunnel for each non-root device,

a designated device selected from a pair of devices associated with each tunnel, the associated tunnel being the designated tunnel of the designated device, and

blocked tunnels for all other tunnels of the devices in the network of layer-2 devices, wherein blocked tunnels are blocked from transmitting advertisement messages.

3. The method for automatic discovery of layer-2 services of claim 2, wherein the transmitting of the advertisement message by each tunnel of each layer-2 device is only on root tunnels and designated tunnels of the layer-2 devices.

4. The method for automatic discovery of layer-2 services of claim 1, wherein the spanning tree provides a unique path from each pair of layer-2 devices.

5. The method for automatic discovery of layer-2 services of claim 1, wherein the transmitting is repeated at predetermined intervals.

6. The method for automatic discovery of layer-2 services of claim 1, wherein the advertisement message transmitted is the best tunnel advertisement message selected from the advertisement message received and from the advertisement message transmitted on the tunnel.

7. The method for automatic discovery of layer-2 services of claim 1, wherein the layer-2 service is a tunnel for establishing a virtual private network.

8. The method for automatic discovery of layer-2 services of claim 7, wherein the layer-2 devices are L2TP access concentrators and wherein the virtual private network between a remote end client and a tunnel server is via L2TP access concentrators in the network according to the spanning tree topology.

9. A system for automatic discovery of layer-2 services across a network of layer-2 devices, comprising a plurality of layer-2 devices in communication with each other to form the network, wherein each layer-2 device is configured to transmit an advertisement message on each tunnel associated with the device, the advertisement message containing information for generating a spanning tree based on spanning tree algorithm, to receive advertisement messages on the tunnels in communication with each layer-2 device, and to process the received advertisement messages to generate a spanning tree topology of the network of layer-2 devices whereby each layer-2 device in the network automatically discovers layer-2 services of other layer-2 devices on the network.

10. The system for automatic discovery of layer-2 services of claim 9, wherein the spanning tree comprises:

a root device selected form the network of layer-2 devices, each tunnel in communication with the root device being a designated tunnel on which advertisement messages are transmitted;

a root tunnel for each non-root device,

a designated device selected from a pair of devices associated with each tunnel, the associated tunnel being the designated tunnel of the designated device; and

blocked tunnels for all other tunnels of the devices in the network of layer-2 devices, wherein blocked tunnels are blocked from transmitting advertisement messages.

11. The system for automatic discovery of layer-2 services of claim 10, wherein the advertisement message transmitted on each tunnel of each layer-2 device is only on root tunnels and designated tunnels of the layer-2 devices.

12. The system for automatic discovery of layer-2 services of claim 9, wherein the spanning tree provides a unique path from each pair of layer-2 devices.

13. The system for automatic discovery of layer-2 services of claim 9, wherein each layer-2 device is configured to repeat the transmission of advertisement messages predetermined intervals.

14. The system for automatic discovery of layer-2 services of claim 9, wherein the advertisement message transmitted is the best tunnel advertisement message selected from the advertisement message received and from the advertisement message transmitted on the tunnel.

15. The system for automatic discovery of layer-2 services of claim 9, wherein the layer-2 service is a tunnel for establishing a virtual private network.

16. The system for automatic discovery of layer-2 services of claim 15, wherein the layer-2 devices are network access servers and wherein the virtual private network between a remote end client and a tunnel server is via network access servers in the network according to the spanning tree topology.

17. A virtual private tunneling network for enabling communication across a virtual private network between a remote end user device and a destination L2TP network server, comprising:

a tunnel switch network comprising a plurality of tunnel switches each in communication with at least one other tunnel switch via a tunnel over an IP network, each of said tunnel switches is preconfigured with a list of tunnels with which it is associated and a list of domains corresponding to each tunnel;

wherein one of said tunnel switches is in direct communication with a network adapted to establish a PPP session between the remote end user device and said one tunnel switch and wherein another one of said tunnel switches is in communication with the destination L2TP network server via a corresponding tunnel,

whereby communication packets between the remote end user device and the L2TP network server are encapsulated and transmitted via a plurality of tunnels corresponding to a plurality of said tunnel switches via the IP network.