System and method for providing a loop free topology in a network environment

• US 8,830,875 B1
• Filed: 06/15/2011
• Issued: 09/09/2014
• Est. Priority Date: 06/15/2011
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Bulusu, Shekher
• Primary Examiner(s): Chriss, Andrew
• Assistant Examiner(s): Lequang, John
• Application Number:
  US13/160,957
• Time in Patent Office: 1,182 Days
• Field of Search: None
• US Class Current: 370/256
• CPC Class Codes: H04L 45/48 Routing tree calculation

Abstract

An example method is provided and includes receiving a bridge protocol data unit (BPDU) on a particular link of a network. A port associated with the particular link is blocked in response to receiving the BPDU. The method also includes communicating a claim message to a spanning tree protocol (STP) root of the network; receiving, from a network element, a reply in which a grant bit is set; and changing the port associated with the particular link to a forwarding state.

Claims

1. A method, comprising:

receiving, at a gateway element, a bridge protocol data unit (BPDU) on a particular link of a network, wherein a port associated with the particular link is blocked in response to receiving the BPDU, and wherein the BDPU is received from a first network element;

communicating, by the gateway element to a second network element, a claim message comprising a claim to a spanning tree protocol (STP) root of the network, wherein the claim message comprises a spanning tree root Type Length Value (TLV) provisioned within intermediate system to intermediate system (IS-IS) protocol;

receiving, from the second network element, a reply in which a grant bit is set, wherein the reply comprises the spanning tree root TLV; and

changing the port associated with the particular link to a forwarding state subsequent to receiving the reply;

wherein the network includes a Data Center Ethernet (DCE) network and a Classical Ethernet (CE) network, which together form a layer-2 (L2) broadcast domain; and

wherein the gateway element is disposed between the DCE network and the CE network.

2. The method of claim 1, further comprising:

executing an intermediate system to intermediate system (IS-IS) protocol for a first set of network links in the network; and

executing a spanning tree protocol (STP) for a second set of network links in the network.

3. The method of claim 1, wherein the spanning tree root TLV is flooded to neighboring network elements through a plurality of link-state packets (LSPs).

4. The method of claim 1, wherein the second network element comprises a part of the Data Center Ethernet (DCE) network and the first network element comprises a part of the Classical Ethernet (CE) network.

5. The method of claim 1, wherein a selected port is configured to receive a superior BPDU, and in response to the superior BPDU, the selected port remains in a blocked state.

6. The method of claim 1, wherein the particular link is a CE link, and wherein the claim message includes a TLV associated with a virtual local area network (VLAN).

18. The method of claim 1, wherein the second network element comprises a second gateway element, the method further comprising:

receiving at the second network element a BDPU on a CE link of the second network element; and

blocking the CE link of the second network element subsequent to the receiving.

7. One or more non-transitory tangible media that includes code for execution, and when executed by a processor operable to perform operations comprising:

receiving, at a gateway element, a bridge protocol data unit (BPDU) on a particular link of a network, wherein a port associated with the particular link is blocked in response to receiving the BPDU, and wherein the BDPU is received from a first network element;

communicating, by the gateway element to a second network element, a claim message comprising a claim to a spanning tree protocol (STP) root of the network, wherein the claim message comprises a spanning tree root Type Length Value (TLV) provisioned within intermediate system to intermediate system (IS-IS) protocol;

receiving, from the second network element, a reply in which a grant bit is set, wherein the reply comprises the spanning tree root TLV; and

changing the port associated with the particular link to a forwarding state subsequent to receiving the reply;

wherein the network includes a Data Center Ethernet (DCE) network and a Classical Ethernet (CE) network, which together form a layer-2 (L2) broadcast domain; and

wherein the gateway element is disposed between the DCE network and the CE network.

8. The media of claim 7, the operations further comprising:

executing an intermediate system to intermediate system (IS-IS) protocol for a first set of network links in the network; and

executing a spanning tree protocol (STP) for a second set of network links in the network.

9. The media of claim 7, wherein the spanning tree root TLV is flooded to neighboring network elements through a plurality of link-state packets (LSPs).

10. The media of claim 7, wherein the second network element comprises a part of the Data Center Ethernet (DCE) network and the first network element comprises a part of the Classical Ethernet (CE) network.

11. The media of claim 7, wherein a selected port is configured to receive a superior BPDU, and in response to the superior BPDU, the selected port remains in a blocked state.

12. The media of claim 7, wherein the particular link is a CE link, and wherein the claim message includes a TLV associated with a virtual local area network (VLAN).

19. The media of claim 7, wherein the second network element comprises a second gateway element, the operations further comprising:

receiving at the second network element a BDPU on a CE link of the second network element; and

blocking the CE link of the second network element subsequent to the receiving.

13. An apparatus, comprising:

a memory element configured to store electronic code,

a processor operable to execute instructions associated with the electronic code, and

a layer-2 (L2) gateway interconnect protocol (L2GIP) module configured to interface with the processor and the memory element such that the apparatus is configured for;

receiving, at a gateway element, a bridge protocol data unit (BPDU) on a particular link of a network, wherein a port associated with the particular link is blocked in response to receiving the BPDU, and wherein the BDPU is received from a first network element;

communicating, by the gateway element to a second network element, a claim message comprising a claim to a spanning tree protocol (STP) root of the network, wherein the claim message comprises a spanning tree root Type Length Value (TLV) provisioned within intermediate system to intermediate system (IS-IS) protocol;

receiving, from the second network element, a reply in which a grant bit is set, wherein the reply comprises the spanning tree root TLV; and

changing the port associated with the particular link to a forwarding state subsequent to receiving the reply;

wherein the network includes a Data Center Ethernet (DCE) network and a Classical Ethernet (CE) network, which together form a layer-2 (L2) broadcast domain; and

wherein the gateway element is disposed between the DCE network and the CE network.

14. The apparatus of claim 13, wherein the apparatus is further configured for:

executing an intermediate system to intermediate system (IS-IS) protocol for a first set of network links in the network; and

executing a spanning tree protocol (STP) for a second set of network links in the network.

15. The apparatus of claim 13, wherein the spanning tree root TLV is flooded to neighboring network elements through a plurality of link-state packets (LSPs).

16. The apparatus of claim 13, wherein the second network element comprises a part of the Data Center Ethernet (DCE) network and the first network element comprises a part of the Classical Ethernet (CE) network.

17. The apparatus of claim 13, wherein a selected port is configured to receive a superior BPDU, and in response to the superior BPDU, the selected port remains in a blocked state.

20. The apparatus of claim 13, wherein the second network element comprises a second gateway element, the apparatus further being configured for:

receiving at the second network element a BDPU on a CE link of the second network element; and

blocking the CE link of the second network element subsequent to the receiving.