Wireless mesh network including resilient backhaul links and WLAN traffic local switching

• US 9,408,249 B2
• Filed: 12/03/2013
• Issued: 08/02/2016
• Est. Priority Date: 12/03/2013
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Pang, Tak Ming, Meier, Robert C., Na, Yanxin, Edward, Emburey Samrex
• Primary Examiner(s): Mered, Habte
• Application Number:
  US14/095,406
• Publication Number:
  US 20150156815A1
• Time in Patent Office: 973 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04L 45/122 by minimising distances, e.g. by selecting a route with minimum of number of hops
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/48 Routing tree calculation
• CPC Class Codes: H04W 40/24 Connectivity information management, e.g. connectivity discovery or connectivity update
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A wireless mesh network includes mesh APs and a root AP forming a root of a tree of the mesh APs in which the mesh APs are linked back to the root AP over wireless backhaul links. The root AP has a wired connection to a wired network. An AP detects a loss of connectivity to a controller through which traffic associated with the AP is normally routed to and from the wired network. In response, if the AP is the root AP, the root AP operates as a proxy controller through which the traffic may be routed. The AP maintains connectivity with parent and child APs over the wireless backhaul links.

Claims

1. A method comprising:

at an access point (AP) in a wireless mesh network including a plurality of mesh APs and a root AP forming a root of a tree of the mesh APs in which the mesh APs are linked back to the root AP through parent-child relationships over wireless backhaul links, the root AP having a wired connection to a wired network;

advertising to each child AP of the AP an actual path-cost leading back to the root AP; and

after the advertising, detecting a loss of connectivity from the AP to a controller of the mesh network through which traffic to and from the wireless mesh network is normally routed from and to the wired network, and in response to detecting the loss of connectivity;

if the AP is the root AP, operating the root AP as a proxy controller through which traffic to and from the wireless mesh network is routed from and to the wired network;

notifying each child AP of the loss of connectivity;

maintaining connectivity with parent and child APs over the wireless backhaul links that exist when the loss of connectivity is detected, so as to maintain the tree; and

advertising to each child AP an artificially reduced path-cost that is less than an actual path cost so as to inhibit each child AP from roaming to a different parent AP during the loss of connectivity.

2. The method of claim 1, further comprising, at the AP:

before detecting the loss of connectivity to the controller, executing a state machine having states and associated protocol timers defined according to a mesh network control protocol; and

in response to detecting a loss of connectivity to the controller;

continuing to execute the state machine in a current state and to operate the protocol timers; and

attempting to rediscover a controller.

3. The method of claim 1, further comprising, at the AP, if connectivity with the controller is detected, advertising to each child AP the actual path-cost.

4. The method of claim 1, further comprising, at the AP, in response to detecting the loss of connectivity to the controller:

maintaining connectivity with wireless clients served by the AP and through which traffic to and from the wireless client is routed from and to the mesh network.

5. The method of claim 4, further comprising at the AP, in response to detecting loss connectivity:

if the AP is the root AP, determining whether the root AP is connected to a router in the wired network; and

if it is determined that the root AP is not connected with a local router, instructing the mesh APs to break-down the backhaul links.

6. The method of claim 1, further comprising, at the AP:

storing mappings between one or more wireless local area networks (WLANs) served by the AP and one or more virtual local area networks (VLANs) configured on the wired network to which the WLANs are assigned;

receiving WLAN/VLAN mappings from the parent AP that originated at the root AP and that reflect the VLANs configured on the wired network; and

if the received WLAN/VLAN mappings differ from the stored WLAN/VLAN mappings, updating the stored WLAN/VLAN mappings with the received WLAN/VLAN mappings.

7. The method of claim 6, further comprising, at the AP:

receiving WLAN/VLAN mappings from one or more child APs;

sending the stored WLAN/VLAN mappings and the WLAN/VLAN mappings received from the one or more child APs to the parent AP; and

if the AP is the root AP;

storing the WLAN/VLAN mappings for each mesh AP in the tree; and

if the WLAN/VLAN mappings for a given mesh AP received by the root AP differ from the corresponding WLAN/VLAN mappings stored in the root AP, updating the WLAN/VLAN mappings stored in the root AP with the received WLAN/VLAN bindings.

8. An apparatus comprising:

one or more radios in an access point (AP) configured to communicate over backhaul links of a wireless mesh network including a plurality of mesh APs and a root AP forming a root of a tree of the mesh APs in which the mesh APs are linked back to the root AP through parent-child relationships over wireless backhaul links, the root AP having a wired connection to a wired network; and

a processor coupled to the one or more radios, the processor configured to;

advertise to each child AP of the AP an actual path-cost leading back to the root AP; and

after advertising the actual path-cost, detect a loss of connectivity to a controller of the mesh network through which traffic to and from the wireless mesh network is normally routed from and to the wired network, and in response to detecting the loss of connectivity;

if the AP is the root AP, operate as a proxy controller through which traffic to and from the wireless mesh network is routed from and to the wired network;

notify each child AP of the loss of connectivity;

maintain connectivity with parent and child APs over the wireless backhaul links that exist when the loss of connectivity is detected, so as to maintain the tree; and

advertise to each child AP an artificially reduced path-cost that is less than an actual path cost so as to inhibit each child AP from roaming to a different parent AP during the loss of connectivity.

9. The apparatus of claim 8, wherein the processor is further configured to:

before the loss of connectivity to the controller, execute a state machine having states and associated protocol timers defined according to a mesh network control protocol; and

in response to detecting the loss of connectivity to the controller;

continue to execute the state machine in a current state and to operate the protocol timers; and

attempt to rediscover a controller.

10. The apparatus of claim 8, wherein the processor is further configured to, if connectivity with the controller is detected, advertise to each child AP the actual path-cost.

11. The apparatus of claim 8, wherein the processor is further configured to, in response to detecting the loss of connectivity to the controller:

maintain connectivity with wireless clients served by the AP to which the processor is coupled and through which traffic to and from the wireless client is routed from and to the mesh network.

12. The apparatus of claim 11, wherein the processor is further configured to, in response to detecting loss of connectivity:

if the AP is the root AP, determine whether the root AP is connected to a router in the wired network; and

if it is determined that the root AP is not connected with a local router, instruct the mesh APs to break-down the backhaul links.

13. The apparatus of claim 8, wherein the processor is further configured to:

store mappings between one or more wireless local area networks (WLANs) served by the AP and one or more virtual local area networks (VLANs) configured on the wired network to which the WLANs are assigned;

receive WLAN/VLAN mappings from the parent AP that originated at the root AP and that reflect the VLANs configured on the wired network; and

if the received WLAN/VLAN mappings differ from the stored WLAN/VLAN mappings, update the stored WLAN/VLAN mappings with the received WLAN/VLAN mappings.

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

receive WLAN/VLAN mappings from one or more child APs;

send the stored WLAN/VLAN mappings and the WLAN/VLAN mappings received from the one or more child APs to the parent AP; and

if the AP is the root AP;

store the WLAN/VLAN mappings for each mesh AP in the tree; and

if the WLAN/VLAN mappings for a given mesh AP received by the root AP differ from the corresponding WLAN/VLAN mappings stored in the root AP, update the WLAN/VLAN mappings stored in the root AP with the received WLAN/VLAN bindings.

15. A non-transitory processor readable medium storing instructions that, when executed by a processor, cause the processor to:

at an access point (AP) in a wireless mesh network including a plurality of mesh APs and a root AP forming a root of a tree of the mesh APs in which the mesh APs are linked back to the root AP through parent-child relationships over wireless backhaul links, the root AP having a wired connection to a wired network;

advertise to each child AP of the AP an actual path-cost leading back to the root AP; and

after advertising the actual path-cost, detect a loss of connectivity from the AP to a controller of the mesh network through which traffic to and from the wireless mesh network is normally routed from and to the wired network, and in response to detecting the loss of connectivity;

if the AP is the root AP, operate the root AP as a proxy controller through which traffic to and from the wireless mesh network is routed from and to the wired network;

notify each child AP of the loss of connectivity;

maintain connectivity with parent and child APs over the wireless backhaul links that exist when the loss of connectivity is detected, so as to maintain the tree; and

advertise to each child AP an artificially reduced path-cost that is less than an actual path cost so as to inhibit each child AP from roaming to a different parent AP during the loss of connectivity.

16. The processor readable medium of claim 15, further comprising instructions to cause the processor to:

before detecting the loss of connectivity to the controller, execute a state machine having states and associated protocol timers defined according to a mesh network control protocol; and

in response to detecting a loss of connectivity to the controller;

continue to execute the state machine in a current state and to operate the protocol timers; and

attempt to rediscover a controller.

17. The processor readable medium of claim 15, further comprising instructions to cause the processor to, if connectivity with the controller is detected, advertise to each child AP the actual path-cost.

18. The processor readable medium of claim 15, further comprising instructions to cause the processor to, in response to detecting the loss of connectivity to the controller:

maintain connectivity with wireless clients served by the AP and through which traffic to and from the wireless client is routed from and to the mesh network.

19. The processor readable medium of claim 18, further comprising instructions to cause the processor to, in response to detecting loss connectivity:

if the AP is the root AP, determine whether the root AP is connected to a local router in the wired network; and

if it is determined that the root AP is not connected with a local router, instruct the mesh APs to break-down the backhaul links.

20. The processor readable medium of claim 15, further comprising instructions to cause the processor to:

store mappings between one or more wireless local area networks (WLANs) served by the AP and one or more virtual local area networks (VLANs) configured on the wired network to which the WLANs are assigned;

receive WLAN/VLAN mappings from the parent AP that originated at the root AP and that reflect the VLANs configured on the wired network; and

if the received WLAN/VLAN mappings differ from the stored WLAN/VLAN mappings, update the stored WLAN/VLAN mappings with the received WLAN/VLAN mappings.

21. The processor readable medium of claim 20, further comprising instructions to cause the processor to:

receive WLAN/VLAN mappings from one or more child APs;

send the stored WLAN/VLAN mappings and the WLAN/VLAN mappings received from the one or more child APs to the parent AP; and

if the AP is the root AP;

store the WLAN/VLAN mappings for each mesh AP in the tree; and

if the WLAN/VLAN mappings for a given mesh AP received by the root AP differ from the corresponding WLAN/VLAN mappings stored in the root AP, update the WLAN/VLAN mappings stored in the root AP with the received WLAN/VLAN bindings.