Spanning tree protocol for wireless networks

• US 7,653,011 B2
• Filed: 02/10/2006
• Issued: 01/26/2010
• Est. Priority Date: 05/31/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Finn, Norman W., Rahman, Shahriar I.
• Primary Examiner(s): Moe; Aung S
• Assistant Examiner(s): ELLIOTT IV, BENJAMIN H
• Application Number:
  US11/351,433
• Publication Number:
  US 20060280131A1
• Time in Patent Office: 1,446 Days
• Field of Search: 370/229, 370/238, 370/254, 370/256, 370/395.31
• US Class Current: 370/256
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/123 Evaluation of link metrics techniques for monitoring network metrics H04L43/08
• CPC Class Codes: H04L 45/48 Routing tree calculation
• CPC Class Codes: H04W 40/12 based on transmission quality or channel quality
• CPC Class Codes: H04W 40/24 Connectivity information management, e.g. connectivity discovery or connectivity update
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method of implementing a spanning tree protocol for a wireless network conforming to a wireless network standard, the spanning tree protocol substantially conforming to the IEEE 802.1 standard, including a first wireless bridging node wirelessly transmitting BPDU information to other wireless bridging nodes of the network or wirelessly receiving BPDU information from other wireless bridging nodes, the BPDU information encapsulated in one or more control/management frames, e.g., beacon or probe response frames of the wireless network standard, the BPDU information relating to a spanning tree topology containing the first and other wireless bridging nodes.

Claims

1. A method in a first wireless mesh node, the method comprising:

establishing and/or maintaining, in collaboration with other wireless mesh nodes, a wireless spanning tree topology in a wireless mesh network that includes the first wireless mesh node and the other wireless mesh nodes, the wireless mesh network conforming to a wireless network standard, the wireless spanning tree topology according to a wireless spanning tree protocol substantially conforming to a standard IEEE 802.1 spanning tree protocol, the wireless network including the first wireless mesh node and at least two other wireless mesh nodes, the wireless network standard providing a mechanism for a wireless network entity to wirelessly communicate with other wireless network entities using control/management frames for the exchange of wireless network information, the wireless spanning tree protocol acting to determine the spanning tree topology amongst the wireless mesh nodes, including a root wireless node, the establishing and/or maintaining comprising;

wirelessly transmitting path cost information in the form of one or more path cost information elements to other wireless mesh nodes of the wireless mesh network, the one or more path cost information elements being encapsulated in one or more control/management frames, the path cost information relating to a spanning tree topology containing the first and one or more other wireless mesh nodes,

wirelessly receiving one or more beacon or probe response frames from one or more other wireless mesh nodes of the network, the received beacon or probe response frames encapsulating path cost information,

wherein the root wireless node is not required to have a wired network interface,

wherein each path cost information element includes a path cost designed for wireless communication that has more than one possible value between two mesh nodes that are connectable, and may include a bridging protocol data unit (“

BPDU”

) that substantially conforms to a standard IEEE 802.1 spanning tree protocol BPDU, but with a path cost different than a standard IEEE 802.1 spanning tree protocol BPDU path cost in that the path cost is designed for wireless communication and has more than one possible value for a path between two mesh nodes that are connectable, and

wherein the wireless network standard provides a mechanism for wireless network entities to wirelessly transmit beacon or probe response frames to other wireless network entities to advertise the radio characteristics of the wireless network entity, and wherein the control/management frames that encapsulate the one or more path cost information elements are beacon or probe response frames, and

either

A) wherein the wirelessly transmitting and receiving of the beacon or probe response frames encapsulating the one or more path cost information elements is in a separate, low-rate channel,

or

B) wherein the received beacon or probe response frames encapsulate an “

I'"'"'m alive”

message, and the method further includes waiting until a pre-defined number of beacon frames from the other wireless mesh node are missed; and

tearing down the radio-link from the other wireless mesh node only after the pre-defined number of beacon frames are missed,

or

C) wherein the wireless network includes an uplink to another network, the other network linked to an authenticating server, and the method further comprises the first wireless mesh node establishing security credentials with the authenticating server, the root bridge storing security credentials of all members of the spanning tree topology.

2. A method as recited in claim 1, wherein the wireless standard is the IEEE 802.11 wireless LAN standard.

3. A method as recited in claim 1, wherein a beacon or probe response frame from the first wireless -mesh node includes an indication of whether or not at least one path cost information element is included.

4. A method as recited in claim 1, wherein the encapsulated path cost information comprises one or more path cost information elements, the method further comprising:

using the encapsulated BPDU information received in the beacon frames from the other wireless mesh nodes to discover the spanning tree topology in the first wireless mesh node'"'"'s vicinity, and further to find the best path to the root mesh mode of the discovered spanning tree topology in the vicinity, such that a decision as to whether or not to establish a control radio link that includes the first wireless mesh node in the spanning tree topology is possible when the spanning tree topology is first established.

5. A method as recited in claim 1, wherein the encapsulated path cost information comprises one or more path cost information elements, the method further comprising:

using the encapsulated one or more path cost information elements received in the beacon frames from the other wireless mesh nodes to discover the next other wireless mesh node in the best path to the root mesh node of the spanning tree topology prior to establishing a forwarding radio link with the next other wireless mesh node.

6. A method as recited in claim 1, wherein the encapsulated path cost information comprises one or more path cost information elements and wherein the receiving is as a result of

sending a probe request frame that contains a request to other wireless mesh nodes to send a probe response frame encapsulating one or more path cost information elements, the method further comprising:

using the encapsulated one or more path cost information elements received in the beacon frames from the other wireless mesh nodes to discover the spanning tree topology in the first wireless mesh node'"'"'s vicinity, and farther to find the best path to the root mesh node of the discovered spanning tree topology in the vicinity.

7. A method as recited in claim 1, wherein the encapsulated path cost information comprises one or more path cost information elements and wherein the receiving is as a result of

sending a probe request frame that contains a request to other wireless mesh nodes to send a probe response frame encapsulating one or more path cost information the method further comprising:

using the encapsulated one or more path cost information received in the probe response frames from the other wireless mesh nodes to discover the next other wireless mesh node in the best path to the root bridge of the spanning tree topology prior to establishing a forwarding radio link with the next other wireless mesh node.

8. A method as recited in claim 1, wherein the receiving is of of a probe request frame, the method-further comprising:

sending one or more probe response frames encapsulating one or more path cost information elements in response to the received probe request frame.

9. A method as recited in claim 1, wherein the encapsulated path cost information includes one or more radio parameters for path cost calculation for the path cost between a receiving wireless mesh node and other wireless mesh nodes.

10. A method as recited in claim 9, wherein the path cost for determining the spanning tree topology is a weighted sum of at least two of the included radio parameters.

11. A method as recited in claim 10, wherein the one or more included radio parameters include one or more of the received signal strength, the available transmission power, a measure of mobility of the first wireless mesh node, and the hop count.

12. A method as recited in claim 11, wherein the first wireless mesh node includes a received signal quality calculator to provide a measure of received signal quality, and wherein the one or more included radio parameters includes the measure of the received signal quality.

13. A method as recited in claim 9, wherein the encapsulated path cost information comprises one or more path cost information elements including path costs, the method further comprising:

storing path costs of encapsulated one or more path cost information elements received from other wireless mesh nodes.

14. A method as recited in claim 13, further comprising:

maintaining a forward-delay timer for a Forward Delay as defined for a standard IEEE 802.1 spanning tree protocol; and

when the forward-delay timer expires, establishing a point-to-point radio-link with the wireless mesh node that providing the least-cost path to the root bridge according to the spanning tree topology.

15. A method as recited in claim 1, wherein the encapsulated path cost information comprises one or more path cost information elements including path costs, the method further comprising:

storing path costs of encapsulated one or more path cost information elements received from other wireless mesh nodes.

16. A method as recited in claim 15, farther comprising:

storing radio path costs for alternate and/or backup links to links in the spanning tree topology.

17. A method as recited in claim 1, wherein the encapsulated path cost information comprises one or more path cost information elements, the method further comprising:

storing information on dormant alternate and/or backup links with other wireless mesh nodes;

ascertaining whether or not there is a need to use an alternate and/or backup link; and

upon ascertaining the need for a dormant alternate and/or backup link, activating one or more of the dormant alternate and/or backup links according to the stored information.

18. A method as recited in claim 1 wherein the encapsulated path cost information comprises one or more path cost information elements including path costs:

wherein the encapsulated one or more path cost information elements in the received beacon or probe responses include a priority for the transmitting wireless mesh node, the priority measure taking into account whether or not there is an uplink at the wireless mesh node, and

wherein the establishing and/or maintaining includes selecting the root bridge, and

wherein selecting the root bridge depends on factors including the priority measure wireless mesh nodes.

19. A method as recited in claim 18, wherein the wireless root node is coupled as an uplink to a wired network, and wherein the priority measure further takes into account the link speed of the uplink.

20. A method as recited in claim 18, wherein, in the case there are multiple wireless mesh nodes that have uplinks, each multiple wireless mesh node having an uplink forms a root of a separate spanning tree topology such that multiple spanning tree topologies exist.

21. A method as recited in claim 1, wherein the encapsulated path cost information comprises one or more path cost information elements, the method further comprising:

using the encapsulated one or more path cost information elements received in the beacon frames from the other wireless mesh nodes to discover the spanning tree topology in the first wireless mesh node'"'"'s vicinity, and farther to find the best path to the root bridge of the discovered spanning tree topology in the vicinity,

wherein the encapsulated path cost information provides for the first wireless mesh node to perform mobility operations including one or more of;

negotiating security and QoS parameters with another wireless mesh node;

establishing a logical spanning tree protocol link with another wireless mesh node;

tearing down a logical spanning tree protocol link with a wireless mesh node; and

sending the wireless mesh node and station addresses of all the children of the first wireless mesh node in the spanning tree topology

wherein the spanning tree topology is established before an uplink wireless link is established.

22. A method as recited in claim 1, wherein the encapsulated path cost information comprises one or more path cost information elements, and

wherein the wirelessly transmitting and receiving of the beacon or probe response frames encapsulating the one or more path cost information elements is in a separate, low-rate channel.

23. A method as recited in claim 22, wherein the first mesh node includes two radio transceivers such that the first wireless mesh node can transmit and receive the beacon or probe response frames encapsulating the one or more path cost information elements in the separate, low-rate channel simultaneously to forwarding data.

24. A method as recited in claim 22, wherein the first wireless mesh node includes only a single radio, the method further comprising:

going off-channel to the low-rate control channel to listen for or to transmit beacons encapsulating one or more path cost information elements whenever necessary.

25. A method as recited in claim 1, wherein the encapsulated path cost information comprises one or more path cost information elements including an “

I'"'"'m alive”

message, the method further comprising;

waiting until a pre-defined number of beacons from the other wireless mesh node are missed; and

tearing down the radio-link from the other wireless mesh node only after the pre-defined number of beacon frames are missed.

26. A method as recited in claim 1, wherein the wireless network includes an uplink to another network, the other network linked to an authenticating server, the method further comprising:

the first wireless mesh node establishing security credentials with the authenticating server, and

wherein the root bridge stores security credentials of all members of the spanning tree topology.

27. A first wireless mesh node comprising:

a radio transceiver;

a wireless MAC protocol processor coupled to the radio transceiver, such that the radio transceiver and MAC protocol processor combination is able to wirelessly send and receive frames substantially conforming to a wireless network standard; and

a wireless spanning tree protocol processor coupled to the transceiver and configured to establish an active spanning tree topology in a multi-hop wireless network that includes the first wireless mesh node, the wireless network conforming to the wireless network standard, the wireless network including a plurality of wireless mesh nodes including at least two other wireless network mesh nodes, the wireless network standard providing a mechanism for a wireless network entity to wirelessly communicate with other wireless network entities using control/management frames for the exchange of wireless network information, the active spanning tree topology specifying communication pathways between wireless mesh nodes in the wireless network, the wireless spanning tree protocol processor further configured to maintain information on the spanning tree topology, the active spanning tree topology having a root node, the maintained information including the root node, the establishing being according to a wireless spanning tree protocol that substantially conforms to the standard IEEE 802.1 spanning tree protocol but with a path cost different than a standard IEEE 802.1 spanning tree protocol path cost in that the wireless spanning tree protocol path cost measure is designed for wireless communication and can have more than one possible value between two wireless mesh nodes that are connectable,

wherein the root wireless node is not required to have a wired network interface,

wherein the establishing of the active spanning tree protocol includes receiving spanning tree protocol capabilities from other wireless bridging nodes in control/management frames that encapsulate path cost information as one or more path cost information elements, and announcing the spanning tree protocol capabilities of the first wireless mesh node by transmitting control/management frames that encapsulate path cost information as one or more path cost information elements,

wherein each path cost information element includes the path cost measure designed for wireless communication that has more than one possible value between two mesh nodes that are connectable,

wherein each path cost information element may include one or more bridging protocol data unit (“

BPDUs”

) that substantially conform to standard IEEE 802.1 spanning tree protocol BPDUs, but with a path cost different than a standard IEEE 802.1 spanning tree protocol BPDU path cost in that the path cost is designed for wireless communication and has more than one possible value between two mesh nodes that are connectable,

wherein the wireless network standard provides a mechanism for wireless network entities to wirelessly transmit beacon or probe response frames to other wireless network entities to advertise the radio characteristics of the wireless network entity, and wherein the control/management frames that encapsulate the one or more path cost information elements are beacon or probe response frame, and

either

A) wherein the encapsulated at least one path cost information element provides for a receiving wireless mesh node to discover active spanning tree topologies in the receiving wireless mesh node'"'"'s vicinity, and further provides for the receiving wireless mesh node to find the best path to the wireless root node of the discovered active spanning tree topology in the vicinity, and wherein the encapsulated at least one path cost information element provides for mobility operations,

or

B) wherein the first wireless mesh node is configured to interpret one or more beacon or probe response frames received via the transceiver from one or more other wireless mesh nodes of the network, the received beacon or probe response frames encapsulating path cost information, and further configured in combination with the transceiver such that the wirelessly transmitting of the control/management frames and receiving of the beacon or probe response frames encapsulating the one or more path cost information elements is in a separate, low-rate channel,

or

C) wherein the first wireless mesh node is configured to interpret one or more beacon or probe response frames received via the transceiver from one or more other wireless mesh nodes of the network, the received beacon or probe response frames encapsulating path cost information including an “

I'"'"'m alive”

message, and further configured to cause the first wireless mesh node to wait until a pre-defined number of beacons from the other wireless mesh node are missed; and

to tear down a radio-link from another other wireless mesh node only after the pre-defined number of beacon frames from said another other wireless mesh node are missed.

28. A first wireless mesh node as recited in claim 27, wherein the wireless standard is the IEEE 802.11 wireless LAN standard.

29. A first wireless mesh node as recited in claim 27, wherein a beacon or probe response frame from the first wireless node includes an indication of whether or not at least one cost information element is included.

30. A first wireless mesh node as recited in claim 27, wherein the encapsulated at least one path cost information element provides for a receiving wireless mesh node to discover active spanning tree topologies in the receiving wireless mesh node'"'"'s vicinity, and further provides for the receiving wireless mesh node to find the best path to the wireless root node of the discovered active spanning tree topology in the vicinity.

31. A first wireless mesh node as recited in claim 30, wherein the encapsulated at least one path cost information element provides for the receiving wireless mesh node to discover the next other wireless mesh node in the best path to the wireless root node prior to establishing a forwarding radio link with the next other wireless mesh node.

32. A first wireless mesh node as recited in claim 30, wherein the encapsulated at least one path cost information element provides for mobility operations.

33. A first wireless mesh node as recited in claim 27, wherein the processing system is configured such that the first wireless mesh node can send a probe request frame that contains a request from other wireless mesh nodes to send a probe response frame encapsulating one or more path cost information elements, such that the first wireless mesh node can discover spanning tree topologies in the first wireless mesh node'"'"'s vicinity.

34. A first wireless mesh node as recited in claim 27, wherein the processing system is configured to cause the first wireless mesh node to send a probe response encapsulating one or more path cost information elements in response to a received probe request frame from another wireless mesh node that contains a request to send a probe response frame encapsulating one or more path cost information.

35. A first wireless mesh node as recited in claim 27, wherein the encapsulated at least one path cost information element includes one or more radio parameters for path cost calculation for the path cost between a receiving wireless mesh node and other wireless mesh nodes.

36. A first wireless node as recited in claim 35, wherein the path cost for determining the spanning tree topology is a weighted sum of at least two of the included radio parameters.

37. A first wireless mesh node as recited in claim 36, wherein the one or more included radio parameters include one or more of the received signal strength, the received signal quality, the available transmission power, a measure of mobility of the first wireless mesh node, and the hop count.

38. A first wireless mesh node as recited in claim 35, wherein the processing system includes a memory and is configured to cause the first wireless mesh node to store path costs advertised by other wireless mesh nodes.

39. A first wireless mesh node as recited in claim 35, wherein the spanning tree protocol processor maintains a forward-delay timer, such that when the forward-delay timer expires, the first wireless mesh node establishes a point-to-point radio-link with the wireless mesh node that provides the least-cost path to the root bridge according to the spanning tree topology.

40. A first wireless mesh node as recited in claim 27, wherein the processing system includes a memory and is configured to cause the first wireless mesh node to store radio path costs advertised by other wireless mesh nodes.

41. A first wireless mesh node as recited in claim 40, wherein the processing system further is configured to cause the first wireless mesh node to store radio path costs for alternate and/or backup links.

42. A first wireless mesh node as recited in claim 27, wherein the processing system includes a memory and is configured to cause the first wireless mesh node to store information on dormant alternate and/or backup links with wireless mesh nodes, such that, upon the first wireless mesh node determining, using the spanning tree protocol processor, the need for an alternate and/or backup link, a dormant alternate and/or backup link may be activated according to information stored in the first wireless mesh node.

43. An apparatus in a first wireless mesh node, the apparatus comprising:

means for establishing and/or maintaining, in collaboration with other wireless mesh nodes, a spanning tree topology in a wireless mesh network that includes the first wireless mesh node and the other wireless mesh nodes, the wireless mesh network conforming to a wireless network standard, the spanning tree protocol substantially conforming to a standard IEEE 802.1 spanning tree protocol, the wireless network including a first wireless mesh node and at least two other wireless mesh nodes, the means for operating in the first wireless mesh node, the wireless standard providing a mechanism for a wireless network entity to wirelessly communicate with other wireless network entities using control/management frames for the exchange of wireless network information, the means for establishing and/or maintaining comprising;

means for maintaining information in the first wireless mesh node on a spanning tree topology containing the first and one or more other wireless mesh nodes and determined according to a spanning tree protocol that substantially conforms to a standard IEEE 802.1 spanning tree protocol using a wireless network path cost measure, the maintained information including maintaining the identity of a root node of the spanning tree topology;

means for wirelessly transmitting configured to transmit path cost information as at least one path cost information element to other wireless mesh nodes of the network encapsulated in one or more control/management frames, the at least one path cost information element relating to the spanning tree topology; and

means for wirelessly receiving configured to receive one or more beacon or probe response frames from one or more other wireless mesh nodes of the network, the received beacon or probe response frames encapsulating path cost information,

wherein the root wireless node is not required to have a wired network interface,

wherein each path cost information element includes a path cost designed for wireless communication that has more than one possible value between two mesh points that are connectable, and may include a bridging protocol data unit (“

BPDU”

) that substantially conforms to a standard IEEE 802.1 spanning tree protocol BPDU, but with a path cost different than a standard IEEE 802.1 spanning tree protocol BPDU path cost in that the path cost is designed for wireless communication that has more than one possible value between two mesh points that are connectable, and

wherein the wireless network standard provides a mechanism for wireless network entities to wirelessly transmit beacon or probe response frames to other wireless network entities to advertise the radio characteristics of the wireless network entity, and wherein the control/management frames that encapsulate the one or more path cost information elements are beacon or probe response frames, and

either

A) wherein the means for wirelessly transmitting and the means for wirelessly receiving are configured to wirelessly transmit and wirelessly receive the beacon or probe response frames encapsulating the one or more path cost information elements in a separate, low-rate channel,

or

B) wherein the received beacon or probe response frames encapsulate an “

I'"'"'m alive”

message, and the apparatus further includes means for waiting until a pre-defined number of beacon frames from the other wireless mesh node are missed; and

means for tearing down the radio-link from the other wireless mesh node only after the pre-defined number of beacon frames are missed,

or

C) wherein the wireless network includes an uplink to another network, the other network linked to an authenticating server, and the apparatus further comprises means for establishing security credentials with the authenticating server, the root bridge storing security credentials of all members of the spanning tree topology.

44. An apparatus as recited in claim 43, wherein a beacon or probe response frame from the first wireless mesh node includes an indication of whether or not at least one path cost information element is included.

45. An apparatus as recited in claim 43, wherein the encapsulated path cost information comprises one or more path cost information elements, the apparatus further comprising:

means for using the encapsulated at least one path cost information element received in the beacon frames from the other wireless mesh nodes to discover the next other wireless mesh node in the best path to the root bridge of the spanning tree topology prior to establishing a forwarding radio link with the next other wireless mesh node.

46. An apparatus as recited in claim 43, wherein the encapsulated path cost information comprises one or more path cost information elements, and wherein at least one path cost information element includes one or more radio parameters for path cost calculation for the path cost between a receiving wireless mesh node and other wireless mesh nodes.

47. An apparatus as recited in claim 43, wherein the encapsulated path cost information comprises one or more path cost information elements,

the encapsulated at least one path cost information element including a priority for the transmitting wireless mesh node, the priority measure taking into account whether or not there is an uplink at the wireless mesh node, and

wherein the one or more functions includes selecting the root bridge, and wherein selecting the root bridge depends on factors including the priority measure for the wireless mesh nodes.

48. A computer readable storage medium configured with computer readable code that when executed by at least one processor of a processing system that is included in a first wireless mesh node causes the first wireless mesh node to carry out a method, the computer readable storage medium configured with:

code to cause the first wireless mesh node to establish and/or maintain, in collaboration with other wireless mesh nodes, a spanning tree topology for a wireless mesh network that includes the first wireless mesh node and the other wireless mesh nodes, such that the spanning tree topology determined according to a wireless spanning tree protocol substantially conforms to a standard IEEE 802.1 spanning tree protocol, the wireless network conforming to a wireless network standard, the wireless standard providing a mechanism for a wireless network entity to wirelessly communicate with other wireless network entities using control/management frames for the exchange of wireless network information, the wireless spanning tree protocol acting to determine the spanning tree topology amongst the wireless mesh nodes, including a root wireless node;

code to cause the first wireless mesh node to wirelessly transmit path cost information as at least one path cost information element to other wireless mesh nodes of the wireless mesh network, the one or more path cost information elements being encapsulated in one or more control/management frames, the at least one path cost information element relating to a spanning tree topology containing the first and one or more other wireless mesh nodes; and

code to cause the first wireless mesh node to wirelessly receive one or more beacon or probe response frames from one or more other wireless mesh nodes of the network, the received beacon or probe response frames encapsulating at least one path cost information element,

wherein the root wireless node is not required to have a wired network interface, and

wherein each path cost information element includes a path cost designed for wireless communication that has more than one possible value between two mesh nodes that are connectable and wherein each path cost information element may include a bridging protocol data unit (“

BPDU”

) that substantially conforms to a standard IEEE 802.1 spanning tree protocol BPDU, but with a path cost different than a standard IEEE 802.1 spanning tree protocol BPDU path cost in that the path cost is designed for wireless communication and has more than one possible value between two mesh nodes that are connectable, and

wherein the wireless network standard provides a mechanism for wireless network entities to wirelessly transmit beacon or probe response frames to other wireless network entities to advertise the radio characteristics of the wireless network entity, and wherein the control/management frames that encapsulate the one or more path cost information elements are beacon or probe response frames, and

either

A) wherein the wirelessly transmitting and the wirelessly receiving of the beacon or probe response frames encapsulating the one or more path cost information elements in a separate, low-rate channel,

or

B) wherein the received beacon or probe response frames encapsulate an “

I'"'"'m alive”

message, and wherein the computer readable storage medium is further configured with code to cause the first wireless mesh node to wait until a pre-defined number of beacon frames from the other wireless mesh node are missed; and

to tear down the radio-link from the other wireless mesh node only after the pre-defined number of beacon frames are missed,

or

C) wherein the wireless network includes an uplink to another network, the other network linked to an authenticating server, and the computer readable storage medium is further configured with code to cause the first wireless mesh node to establish security credentials with the authenticating server, the root bridge storing security credentials of all members of the spanning tree topology.

49. A computer readable storage medium as recited in claim 48, wherein a control/management frame from the first wireless mesh node includes an indication of whether or not at least one path cost information element is included.

50. A computer readable storage medium as recited in claim 48, wherein the wireless network standard provides a mechanism for wireless network entities to wirelessly transmit beacon or probe response frames to other wireless network entities to advertise the radio characteristics of the wireless network entity, and wherein the control/management frames that encapsulate the at least one path cost information element are beacon or probe response frames.

51. A computer readable storage medium as recited in claim 50, wherein the code stored in the storage further comprises:

code to cause the first wireless mesh node to use the encapsulated at least one path cost information element received in the beacon frames from the other wireless mesh nodes to discover the next other wireless mesh node in the best path to the root bridge of the spanning tree topology prior to establishing a forwarding radio link with the next other wireless mesh node.

52. A computer readable storage medium as recited in claim 50, wherein the encapsulated at least one path cost information element includes one or more radio parameters for path cost calculation for the path cost between a receiving wireless mesh node and other wireless mesh nodes.

53. A computer readable storage medium as recited in claim 50,

wherein the encapsulated at least one path cost information element in the wirelessly receive one or more beacon or probe response frames from one or more other wireless mesh nodes of the network includes a priority for the transmitting wireless mesh node, the priority measure taking into account whether or not there is an uplink at the wireless mesh node,

wherein the one or more functions includes selecting the root bridge, and wherein selecting the root bridge depends on factors including the priority measure for the wireless mesh nodes.

54. A method in a first wireless network entity, the method comprising:

running a first instance of a wireless spanning tree protocol that substantially conforms to the standard IEEE 802.1 spanning tree protocol, such that the first wireless network entity acts as a first mesh point of a mesh of wireless mesh points in a wireless network that substantially conforms to a wireless network standard, the wireless network standard providing a mechanism for a wireless network entity to wirelessly transmit beacon or probe response frames to other wireless network entities to advertise the radio characteristics of the wireless network entity,

wherein running an instance of a substantially conforming wireless spanning tree protocol in a particular wireless network entity determines a spanning tree topology instance amongst the wireless mesh nodes, including a root wireless node for the tree topology instance, including;

maintaining information on the spanning tree topology instance for a set of wireless network entities that includes the particular wireless network entity, the spanning tree topology instance being for wirelessly communicating among the set of wireless network entities, the maintained information including the identity of a root wireless network entity for the spanning tree topology instance;

wirelessly sending a beacon frame and, in the case a probe request frame was received that includes a path cost information request, a probe response frame, the beacon and/or probe response frame including an indication that path cost information including at least one path cost information element is encapsulated, wherein each path cost information element includes a path cost designed for wireless communication that has more than one possible value between two mesh nodes that are connectable, and wherein each path cost information element may include a bridging protocol data unit (“

BPDU”

) information that substantially conforms to a standard IEEE 802.1 spanning tree protocol BPDU information, but with a path cost different than a standard IEEE 802.1 spanning tree protocol BPDU path cost in that the path cost is calculated according to wireless information and has more than one possible value between two mesh nodes that are connectable; and

as a result of receiving a beacon frame or probe response frame, ascertaining if the received beacon or probe response frame encapsulate path cost information, and if there is encapsulated path cost information, updating the maintained information on the first spanning tree topology, and accordingly modifying any at least one path cost information element for sending in an encapsulated beacon frame or probe response,

wherein each root wireless node for a respective tree topology instance is not required to have a wired network interface,

wherein the wireless network standard provides a mechanism for wireless network entities to wirelessly transmit beacon or probe response frames to other wireless network entities to advertise the radio characteristics of the wireless network entity, and wherein the control/management frames that encapsulate the one or more path cost information elements are beacon or probe response frames, and

either

A) wherein in running an instance, the wirelessly transmitting and receiving of the beacon or probe response frames encapsulating the one or more path cost information elements is in a separate, low-rate channel,

or

B) wherein in running an instance, the received beacon or probe response frames encapsulate an “

I'"'"'m alive”

message, and the running an instance further includes waiting until a pre-defined number of beacon frames from the other wireless mesh node are missed; and

tearing down the radio-link from the other wireless mesh node only after the pre-defined number of beacon frames are missed,

or

C) wherein the wireless network includes an uplink to another network, the other network linked to an authenticating server, and the running an instance further comprises the first wireless mesh node establishing security credentials with the authenticating server, the root bridge storing security credentials of all members of the spanning tree topology.