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Architectural Considerations for 802.11 ESS Mesh

This article discusses the architectural considerations and requirements for implementing 802.11 ESS Mesh networks, including extended range, enhanced reliability, and potential throughput improvements. It also outlines the proposed next steps for this technology.

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Architectural Considerations for 802.11 ESS Mesh

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  1. Architectural Considerations and Requirements for 802.11 ESS Mesh March 16, 2004 Steven Conner Intel Corporation (w.steven.conner@intel.com)

  2. Outline • Review of 802.11 ESS Mesh Scope • Architectural Considerations and Requirements • Proposed Next Steps

  3. Overview: 802.11 Mesh • Mesh is not limited to highly mobile networks with no infrastructure • Also has application in many fixed-infrastructure environments • Extended range and coverage, without requiring additional wires (convenient deployment, cost) • Enhanced redundancy, reliability • Potential throughput improvement • Example networks where 802.11 Mesh is useful: • Home networks, hotspot networks, etc.

  4. Summary of 802.11s PAR Scope Approved by WG in January • Scope: Develop an Infrastructure-Mode 802.11 ESS Mesh with 802.11 MAC/PHY (WDS links) • Scale: Target ~32 active mesh APs • Security: Include support for trusted set of mesh APs controlled by single logical administrative domain • Mesh Topology/Paths: Include support for both broadcast/multicast and radio-channel-aware unicast path selection/data delivery • Multiple-radios: Include support for optional multiple-radios per router • Ensure support for interfacing with higher layers • Enable interoperability, extensibility

  5. 802.11 ESS Mesh Mesh AP Links 802.11 MAC/PHY (4-addr data frames) 802.11 ESS Distribution System (DS) Client-to-AP Links 802.11 MAC/PHY (3-addr data frames) 802.11 BSS How does IEEE 802.11 ESS Mesh fit in to the big picture?

  6. High-Level Requirements for 802.11s ESS Mesh • Interoperability: 802.11 is required to appear to higher layers as a current style 802 LAN (5.1.1.4) • LAN broadcast and unicast delivery • Interfacing to other networks, e.g. bridging and gatewaying • Self-configuring multi-hop topologies and paths • 802.11 MAC/PHY radio-awareness for efficient path selection and data delivery • Maintain WLAN security • New 802.11 security requirements: • AP-to-AP authentication, key distribution, topology/statistics exchange, data forwarding • Don’t break 802.11i for legacy client STA security

  7. 802.11 ESS Mesh Path Formation/Forwarding – Establishment of end-to-end data comm. paths in a mesh network, potentially across multiple radio hops • Key Components: • Multi-hop topology discovery • Radio-aware path selection/data delivery • LAN broadcast • Goals: • Interoperability through standard protocol tuned for core usage model requirements • Extensibility for future applications and technology enhancements ESS Mesh Functional Components • 802.11 ESS Mesh Topology Formation – Mesh APs establish peer-to-peer links between neighbors, resulting in a secure “mesh of connectivity” • Key Components: • AP neighbor discovery • AP-to-AP security (authentication, key distribution, etc.)

  8. Interfacing to Higher-Layers Interfacing to 802.11 Services Unicast Fwding Bcast Fwding Unicast Path Selection LAN Bcast Protocol Radio- Aware Mesh Metrics Neighbor/ Topology Discovery ESS Mesh Security MAC Enhancements for Mesh 802.11s Strawman Architecture Higher- Layers 802.1, IP, etc. 802.11 802.11i 802.11k 802.11e/n MAC 802.11a/b/g/n/… PHY

  9. Proposed Next Steps • Set up telecons to continue architecture discussions • Generate draft high-level architecture doc. • Major functional components and definitions, based on IEEE 802.11 architecture requirements and the PAR • How ESS Mesh fits in with 802.11/802 architecture • Identify potential standard and TG draft sections that will need to be amended • In parallel, begin documenting and prioritizing usage models • Will be used to drive specific requirements for functional component solutions

  10. 802.11s (ESS Mesh) WG Draft Timeline • Jan 04: Approval of PAR/5C by 802.11 WG • Mar 04: Approval by 802 executive committee to start TG • May 04: First ESS Mesh TGs Meeting • May-Sept 04: • Adopt high-level architecture • Prioritize usage models • Adopt detailed requirements for functional component solutions

  11. QuestionsorComments?

  12. Backup

  13. Key benefits of building on 802.11 infrastructure mode: • Immediately applicable to many existing usage models • Existing security models assume infrastructure mode • Infrastructure mode design/implementations tend to be more mature than ad-hoc mode • Ad-hoc mode is broken for multi-hop, power saving, multi-channel, coalescing, etc. • Eliminate requirement to bridge between ad-hoc and infrastructure mode

  14. IEEE 802.11 ESS Mesh PAR • Scope: • To develop an IEEE 802.11 Extended Service Set (ESS) Mesh* with an IEEE 802.11 Wireless Distribution System (WDS) using the IEEE 802.11 MAC/PHY layers that supports both broadcast/multicast and unicast delivery over self-configuring multi-hop topologies. • Purpose: • The IEEE 802.11-1999 (2003 edition) standard provides a four-address frame format for exchanging data packets between APs for the purpose of creating a Wireless Distribution System (WDS), but does not define how to configure or use a WDS. The purpose of the project is to provide a protocol for auto-configuring paths between APs over self-configuring multi-hop topologies in a WDS to support both broadcast/multicast and unicast traffic in an ESS Mesh using the four-address frame format or an extension.

  15. IEEE 802.11 ESS Mesh PAR • Additional Explanatory Notes: • Scope of the Project. An IEEE 802.11 Extended Service Set (ESS) Mesh* is a collection of APs interconnected with wireless links that enable automatic topology learning and dynamic path configuration. • The proposed amendment shall be an extension to the IEEE 802.11 MAC. The amendment will define an architecture and protocol for providing an IEEE 802.11 ESS Mesh using the IEEE 802.11 MAC to create an IEEE 802.11 Wireless Distribution System that supports both broadcast/multicast and unicast delivery at the MAC layer using radio-aware metrics over self-configuring multi-hop topologies. An ESS Mesh is functionally equivalent to a wired ESS, with respect to the STAs relationship with the BSS and ESS. • The amendment shall enable interoperable formation and operation of an ESS Mesh, but shall be extensible to allow for alternative path selection metrics and/or protocols based on application requirements. A target configuration is up to 32 devices participating as AP forwarders in the ESS Mesh. However, larger configurations may also be contemplated by the standard. It is intended that the architecture defined by the amendment shall allow an ESS Mesh to interface with higher layers and to connect with other networks using higher layer protocols. • The amendment shall utilize IEEE 802.11i security mechanisms, or an extension thereof, for the purpose of securing an ESS Mesh in which all of the APs are controlled by a single logical administrative entity for security. The amendment shall allow the use of one or more IEEE 802.11 radios on each AP in the ESS Mesh.

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