Method for avoiding a loop in a network

Patent metadata

Field	Value
Publication number	US-9306838-B2
Application number	US-201514728860-A
Country	US
Kind code	B2
Filing date	Jun 2, 2015
Priority date	Jul 7, 2011
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

According to an example, a method for avoiding a loop in a network, which is performed by each ED in each VPN site, comprises: interacting with other EDs in a same VPN site to elect a DED; assigning an authorized forwarding instance to each ED in the same VPN site when the ED is elected as the DED; obtaining the authorized forwarding instance from the DED when the ED is not elected as the DED; allowing traffic of the authorized forwarding instance transmitted from or to a public network, and blocking traffic of unauthorized forwarding instance transmitted from or to the public network.

First claim

What is claimed is:

1. A method for avoiding a loop in a network having more than two Virtual Private Network (VPN) sites, wherein each VPN site comprises at least two Edge Devices (EDs), the method being performed by an ED and comprising:
interacting with other EDs in a same VPN site to elect a Designated Edge Device (DED);
periodically sending a message carrying one or both of a MAC address and a priority of the ED;
when the VPN site of the ED splits into at least two VPN sites,
blocking traffic of a forwarding instance with a changed spanning Tree Protocol (STP) topology that is transmitted from or to the public network for a preset time period T 2 ;
blocking traffic of all forwarding instances transmitted from or to the public network for a preset time period T 1 if the message from the DED is not received in a preset time period T 0 ;
reelecting a new DED according to the MAC address and/or priority of the ED and the messages sent by other EDs;
assigning an authorized forwarding instance for each ED in the same VPN site when the ED is reelected as the DED;
obtaining the authorized forwarding instance from the reelected DED; and
updating the authorized forwarding instance when the authorized forwarding instance changes;

wherein a sum of T 1 and T 0 is less than T 2 .

2. The method of claim 1 , wherein interacting with other EDs in a same VPN site to elect a DED further comprises:
sending a message carrying one or both of a MAC address and priority of the ED to other EDs in the same VPN site after the ED starts up; and
electing the DED according to the one or both of the MAC address and the priority of the ED and messages sent by other EDs.

3. The method of claim 1 , further comprising, in the ED:
assigning an authorized forwarding instance to each ED in the same VPN site when the ED is elected as the DED;
obtaining the authorized forwarding instance from the DED when the ED is not elected as the DED; and
allowing traffic of the authorized forwarding instance transmitted from or to a public network, and blocking traffic of unauthorized forwarding instance transmitted from or to the public network.

4. The method of claim 3 , wherein assigning an authorized forwarding instance to each ED in the same VPN site further comprises:
for each forwarding instance configured in each ED of the same VPN site, if the forwarding instance is configured only in one ED, assigning the forwarding instance as the authorized forwarding instance to the one ED; and
if the forwarding instance is configured in at least two EDs, determining one of the at least two EDs according to an identity of the forwarding instance and the number of the EDs configured with the forwarding instance, and assigning the forwarding instance as the authorized forwarding instance to the determined ED.

5. The method of claim 4 , wherein determining one of the at least two EDs according to an identity of the forwarding instance and the number of the EDs configured with the forwarding instance comprises:
numbering the EDs configured with the forwarding instance from an initial value;
dividing the identity of the forwarding instance by the number of EDs configured with the forwarding instance, and obtaining a residual value; and
selecting an ED from the EDs configured with the LEV, the number of the selected ED corresponding to the residual value.

6. The method of claim 3 , further comprising:
blocking traffic transmitted from or to the public network of all forwarding instances for a preset time period T 3 when the message is not received from the DED for a preset time period T 4 ;
reelecting a new DED according to the MAC addresses and/or priorities of the EDs carried by the messages received from other EDs in the preset time period T 3 ;
assigning an authorized forwarding instance for each ED in the same VPN site when the ED is reelected as the DED;
obtaining the authorized forwarding instance from the reelected DED; and
updating the authorized forwarding instance when the authorized forwarding instance changes.

7. The method of claim 6 , wherein allowing traffic of the authorized forwarding instance transmitted from or to a public network, and blocking traffic of unauthorized forwarding instance transmitted from or to the public network comprises:
determining a forwarding instance used to conduct packet forwarding in a data plane according to the authorized forwarding instance assigned to the ED; and
allowing traffic of the forwarding instance used to conduct packet forwarding in the data plane transmitted from or to the public network and blocking traffic of other forwarding instances transmitted from or to the public network.

8. The method of claim 3 , further comprising:
when the VPN site of the ED and another VPN site fuse into one new VPN site,
recognizing EDs in the new VPN site;
blocking traffic transmitted from or to the public network of a conflict forwarding instance for a preset time period T 3 ;
reelecting a new DED according to the MAC address and/or priority of the ED and the messages sent by other EDs;
assigning an authorized forwarding instance for each ED in the same VPN site when the ED is reelected as the DED;
obtaining the authorized forwarding instance from the reelected DED; and
updating the authorized forwarding instance when the authorized forwarding instance changes;
wherein the conflict forwarding instance is a forwarding instance assigned to at least two EDs as the authorized forwarding instance in the new VPN site.

9. An edge device (ED) applied in a Virtual Private Network (VPN) site, comprising:
an electing module to interact with other EDs in a same VPN site to elect a Designated Edge Device (DED);
a first processing module to:
periodically send a message carrying one or both of a MAC address and a priority of the ED;
block traffic transmitted from or to the public network of all forwarding instances for a preset time period T 1 when the message is not received from the DED for a preset time period T 0 ; and
reelect a new DED according to one or both of the MAC addresses and the priorities of the EDs carried by the messages received from other EDs in the preset time period T 1 ; and

a second processing module to:
assign an authorized forwarding instance for each ED in the same VPN site when the ED is reelected as the DED;
obtain the authorized forwarding instance from the reelected DED when the ED is not reelected as the DED; and
update the authorized forwarding instance when the authorized forwarding instance changes.

10. The edge device of claim 9 , wherein
the electing module is to send a message carrying one or both of a MAC address and a priority of the ED to other EDs after the ED starts up, and elect the DED according to one or both of the MAC address and the priority of the ED and the messages sent by other EDs.

11. The edge device of claim 9 , further comprising:
an assigning module to assign an authorized forwarding instance to each ED in the same VPN site when the ED is elected as the DED;
an obtaining module to obtain the authorized forwarding instance from the DED when the ED is not elected as the DED; and
a controlling module to allow traffic of the authorized forwarding instance transmitted from or to a public network, and block traffic of an unauthorized forwarding instance transmitted from or to the public network.

12. The edge device of claim 11 , wherein:
the assigning module is to, for each forwarding instance configured in each ED of the same VPN site, if the forwarding instance is configured only in one ED, assign the forwarding instance as the authorized forwarding instance to the one E

Assignees

• Hangzhou H3C Tech Co Ltd

Inventors

• Zhou Wan

Classifications

• H04L47/70

  Admission control; Resource allocation · CPC title

• H04L47/10

  Flow control; Congestion control · CPC title

• H04L45/04

  Interdomain routing, e.g. hierarchical routing · CPC title

• H04L45/18 Primary

  Loop-free operations · CPC title

• H04L12/4641

  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 title