Is Spanning Tree Protocol Right for ESS Mesh? May 2004 Is Spanning Tree Protocol Right for ESS Mesh? Tyan-Shu Jou, Ted Kuo, and Ming Sheu tsjou@janusysnetworks.com Janusys Networks, Inc. Date: May 11, 2004 Tyan-Shu Jou, et al., Janusys Networks

Forwarding Topologies to Prevent Traffic Looping on an ESS Mesh Month 2002 doc.: IEEE 802.11-02/xxxr0 May 2004 Forwarding Topologies to Prevent Traffic Looping on an ESS Mesh One global spanning tree (802.1d/802.1w) Shortest Path based routing algorithms (Spanning tree algorithms are essentially Distance Vector routing protocol running at Layer 2 that computes the lowest cost paths to the designated Root node) Tyan-Shu Jou, et al., Janusys Networks John Doe, His Company

Advantages of Using Spanning Tree on ESS Mesh Month 2002 doc.: IEEE 802.11-02/xxxr0 May 2004 Advantages of Using Spanning Tree on ESS Mesh Proven & standard algorithm Rapid Spanning Tree (802.1w) can converge within a short time (Although on wireless networks, link up/down detection are timer dependent) Low processing overhead Tyan-Shu Jou, et al., Janusys Networks John Doe, His Company

Disadvantages of using Spanning Tree on ESS Mesh May 2004 Disadvantages of using Spanning Tree on ESS Mesh Not optimal connections between wireless peers Not intended for dynamic topology – the global tree has to be reconstructed for any link change Load sharing is difficult—eg., in case multiple border nodes to wired network exist Difficult to reflect dynamic metrics such as receiving signal strength Tyan-Shu Jou, et al., Janusys Networks

Examples of Shortest-path forwarding Algorithms May 2004 Examples of Shortest-path forwarding Algorithms OSPFv3 extension for wireless ad-hoc network IETF MANET: 4 IP routing protocols for wireless ad-hoc network Many others (NRL Dynamic backbone, Zigbee, …) Tyan-Shu Jou, et al., Janusys Networks

May 2004 Questions for the SG Should we decide which layer (or, what address) the forwarding algorithm should be based? Should we decide one forwarding algorithm? Can we only define the communication message format rather than the algorithm? Can we only define the MAC interface so the same hardware module can be shared? How much interoperability among vendors required? Tyan-Shu Jou, et al., Janusys Networks