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Multiple Radio MP

Multiple Radio MP. Date: 2008-11-10. Authors:. Baseline STA Assumption. IEEE 802.11 defines one MAC/PHY for a STA with a MAC address. Each STA has its own MAC address. A product can include multiple STAs in it. dot11StationConfigTable includes multiple dot11StationConfigEntry,

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Multiple Radio MP

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  1. Multiple Radio MP Date: 2008-11-10 Authors: L. Chu et al.

  2. Baseline STA Assumption • IEEE 802.11 defines one MAC/PHY for a STA with a MAC address. • Each STA has its own MAC address. • A product can include multiple STAs in it. • dot11StationConfigTable includes multiple dot11StationConfigEntry, • each dot11StationConfigEntry has its unique MAC address, EDCA parameter set… • When a product includes multiple STAs, the interaction among multiple STAs are not defined by the standard. Note: in this presentation, STA, radio, interface have one-to-one relationship in a multiple-radio MP. L. Chu et al.

  3. MP3,2 MP3,1 MP6,1 MP3 MP2,1 MP6 MPy MP7,2 MP2 MP5,1 MP7,1 MP5 MP7 MP1,1 MP4,2 MP8,1 MP4,1 MP1 MP8 MP4 Current Multiple Radio MP Support • Mesh security optimizes the key acquiring procedure in a multiple radio mesh network. • Each STA has its own MAC address to identify it. • An MP with multiple STAs selects one MAC address as its identifier. • multiple radios in an MP are active simultaneously. Radio/STA/Interface MPy,2 MPy,1 STA ID STA ID The radio in the end point of the red and green links work in different channels. L. Chu et al.

  4. Current Multiple Radio MP Support (Cont’d) • The current 802.11s architecture does not harmonize security optimization with routing/forwarding. • Mesh security optimization is on top of each STA in an MP, • Both routing and forwarding belong to the MAC of each STA in an MP. • There is no text about how to create, accept, process PREQ/PREP/PERR in a multiple radio MP. • The forwarding information does not show which STA (interface) will be used. • The frame forwarding procedure does not indicate how to forward a frame in a multiple radio MP. L. Chu et al.

  5. MP3,2 MP3,1 MP6,1 MP3 MP2,1 MP6 MP7,2 MP2 MP5,1 MP7,1 MP5 MP7 MP1,1 MP4,2 MP8,1 MP4,1 MP1 MP8 MP4 Security Optimization with Routing • The security optimization can not be implemented without multiple-radio routing/forwarding support. supplicant MP1 mesh authenticator mesh key distributor MP5 AS MP3 Peer Link Establishment MA advertises services enabling supplicant to join. 802.11 Management EAP Authentication EAP Authentication EAP Authentication EAP over RADIUS EAPoL via Mesh Data EAP via Mesh Action MA enables supplicant to perform EAP authentication. MA obtains a derived key to enable handshake with supplicant. Key Delivery 4-way Handshake via Mesh Action EAPoL via Mesh Data MA derives PTK to secure link with supplicant. Key Holder setup handshake via Mesh Action MP5 tries to find a path to MP1, MP32 broadcast PREQ only in red channel. MP1 will never receive this PREQ. MP5 can not send this frame since it can not find a path to MP1. MP3 and MP4 do not support inter-radio path selection. But they support security optimization. L. Chu et al.

  6. MAC_SAP Routing, Forwarding, Key Management, Link Management… MLME_SAP MLME_SAP MAC MAC MLME MLME SME SME PHY_SAP PHY_SAP The source MP sends out frames PLME_SAP PHY PLME_SAP PLME PHY PLME The destination MP receives frames MP Architecture With Multiple Radio Support • MP routing, forwarding, key management, link management are on top of all STAs with mesh functionality. An intermediate MP forwards frames L. Chu et al.

  7. A simple multi-radio HWMP protocol should be defined. The shortest path selection algorithm is still used. The factor if the hops of a path work in different channels has no influence to the path selection. Only the link metric is considered when selecting a path. Otherwise, HWMP can not be used. Each multiple-radio MP indicates an interface address (e.g. lowest MAC address of all interfaces) as its MP ID (MP main address). Each interface in an MP has its own sequence number. Another option is that there is only one sequence number in a multiple radio MP. Each interface in an MP can be used as the source address or destination address. MAC layer provides this flexibility. Up layer or MLME decides which address will be used. Multiple Radio HWMP Introduction L. Chu et al.

  8. The following information maintained by an intermediate MP allows it to perform its path selection and forwarding functions: Destination MAC address, Next hop MAC address, Interface address for next hop, Precursor MAC address, Interface address for precursor hop, Airtime metric, Lifetime. When creating/updating forwarding or reverse path information, the interface (from which the PREQ/PREP is transmitted/received) information will also be updated besides the destination address, the next hop address, sequence number, lifetime. Forwarding Information Definition in Multiple Radio MP L. Chu et al.

  9. An MP with multiple radios compares all the MAC addresses with address 3 to see if it is the destination of the received frames. An MP with multiple radios selects the interface based on the routing information to queue frame for transmission. Additional Data Frame Forwarding in Multiple Radio MP L. Chu et al.

  10. A multiple radio MP broadcasts PREQ it creates or accepts using all its radios. When creating a PREQ for the frames from the MLME, the originator uses its main address to fill the originator address field. The destination address of PREQ is copied from the received management frame/MLME primitive. When creating a PREQ for the data frames, the originator uses the source MAC address of the data frame/primitive to fill the originator address field. The destination address of PREQ is copied from data frame’s destination address. When deciding if the PREQ is accepted, all the MAC addresses of the receiving MP are compared with the destination address of the PREQ. When initiating a PREP on behalf of another MP, an intermediate MP updates its forwarding information by placing the last hop MP (from which it received the PREQ) into the precursor list for the forward path entry for the destination and the interface (by which it receives the PREQ) into the precursor interface. In addition, this intermediate MP also updates its forwarding information for the MP originating the PREQ by placing the next hop and the interface toward the destination in the precursor list for the reverse path entry. Additional PREQ Processing in Multiple Radio MP L. Chu et al.

  11. When deciding if it is the destination of a PREQ, an MP with multiple radios compares all its MAC addresses with the destination address of the PREQ. If each interface has its own sequence number, the sequence number related to the destination MAC address is increased according to target sequence number updating rules before transmitting a PREP. Otherwise the sequence number related to the destination MP is increased according to target sequence number updating rules before transmitting a PREP. The destination address will be copied from the received PREQ when the destination MP create a PREP. If the MP propagates the PREP, the precursor list for the Destination Address is updated by adding the next hop MP to which the PREP is propagated. The precursor interface for the destination address is updated by adding the interface by which the PREP is propagated. In addition, at the MP the precursor list for the originator address is updated by adding the next hop MP towards the Destination Address. The interface for the originator address is updated by adding the interface that the PREP is received. Additional PREP Processing in Multiple Radio MP L. Chu et al.

  12. A multiple radio MP selects broadcast radios based on the precursor interface of the forwarding information if PERR broadcast is used. Broadcast PERR in all interfaces may not be necessary. A multiple radio MP broadcasts RANNs it creates or accepts using all its radios. When an originator with multiple radios creates a RANN, the originator uses its main MAC address to fill the originator address field. A multiple radio MP registers all its MAC addresses with a root. additional PERR/RANN Processing in Multiple Radio MP L. Chu et al.

  13. Harmonizing security optimization with HWMP routing protocol. Harmonizing security optimization and the updated HWMP with 802.11 architecture. Minor change to HWMP: Using the current airtime metric definition. The path metric is just the sum of link metrics without considering the channel difference used by each link. Conclusion L. Chu et al.

  14. Backup Slides L. Chu et al.

  15. Mesh Security Optimization • The initial authentication should only be launched once when an MP join the mesh network, no matter how many radios it has. • Authentication credential is issued one MP device. • One PMK-MKD and one MKDK for an MP, shared by all the radios. • Different radio in the same MP should use different PTK. • Distribute keys for radios of the device through one time initial authentication procedure. • There should be one MPTK-KD between an MA and MKD. • The communication between MKD and MP is not tied to a peer link with MAC addresses. L. Chu et al.

  16. Mesh Security Optimization (Cont’d) • Clarify two identifiers • MP-ID: the identifier of the MP. It could be one of the MAC addresses of the MP if it has more than one PHY, and it could not be changed once it determined. • MPA: the MAC address of the communicating radio module of the MP. • Three roles when MP doing authentication and key hierarchy, and different ID names to identify the roles which actually is ‘MP-ID’. • Amend the current security solution defined in D2.0 • Bind PMK-MKD ,MKDK and PMK-MA to SP-ID instead of SPA • MeshTopLevelKeyData = KDF-768(XXKey, “Mesh Key Derivation”,MeshID, MKD-NAS-ID, MKDD-ID, SPA SP-ID) • Only one MPTK-KD between an MA and MKD • The key is to protect the communication between the two node entities, not the link level • PTKs should bind with peer link MAC addresses • Rename the ‘MA-ID’ into ‘MAA’ (Mesh Authenticator Address), because the MAA has the same definition of ‘MA-ID’ in 802.11s D2.0 L. Chu et al.

  17. IP Routing and Forwarding • There is one routing/forwarding which are on top of all interfaces. Routing TCP/UDP IP Forwarding LLC/MAC LLC/MAC PHY PHY L. Chu et al.

  18. Bridging • There is one routing/forwarding for all interfaces. Higher Layer Entities (Spanning Tree Protocol Entity, Bridge Management etc.) LLC LLC MAC Relay Entity MAC MAC PHY PHY L. Chu et al.

  19. MP3,2 MP3,1 MP3 Path Selection without Multiple Radio Support • MP4 does not support inter-Radio forwarding. MP3 and MP7 support inter-radio forwarding. • The path between MP4,1 and MP7,2 is shown in blue arrows. • This is a live path loop and non-optimized path! Link metric MP6 STA ID 3 1 STA ID MP6,1 m 2 MPy,1 MP2,1 1 MPx,1 MP2 MPx MPy MP7,2 MP5,1 MP7,1 1 MP5 1 MP7 1 MP1,1 The radio in the end point of the red and green links work in different channels. MP5,1 1 MP4,2 MP4,1 1 MP1 MP5 MP4 L. Chu et al.

  20. MP3,2 MP3,1 MP3 Path Selection without Multiple Radio Support • MP3, MP4 and MP7 do not support inter-Radio forwarding. • The path between MP1 and MP5 can not be found. • It is strange that two MPs are in one mesh network, but can not communicate with each other. Link metric MP6 STA ID 3 1 STA ID MP6,1 m 2 MPy,1 MP2,1 1 MPx,1 MP2 MPx MPy MP7,2 MP5,1 MP7,1 1 MP5 1 MP7 1 MP1,1 MP5,1 1 MP4,2 MP4,1 1 MP1 MP5 MP4 L. Chu et al.

  21. References [1] Changdong Fan etc. 11-08/317r6, “Authentication and key management of MP with multiple radios”. L. Chu et al.

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