1. doc.: IEEE 802.11-04/0598r0 Submission May 2004 Tyan-Shu Jou, et al., Janusys NetworksSlide 1 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

2. doc.: IEEE 802.11-04/0598r0 Submission May 2004 Tyan-Shu Jou, et al., Janusys NetworksSlide 2 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)

3. doc.: IEEE 802.11-04/0598r0 Submission May 2004 Tyan-Shu Jou, et al., Janusys NetworksSlide 3 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

4. doc.: IEEE 802.11-04/0598r0 Submission May 2004 Tyan-Shu Jou, et al., Janusys NetworksSlide 4 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

5. doc.: IEEE 802.11-04/0598r0 Submission May 2004 Tyan-Shu Jou, et al., Janusys NetworksSlide 5 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, …)

6. doc.: IEEE 802.11-04/0598r0 Submission May 2004 Tyan-Shu Jou, et al., Janusys NetworksSlide 6 Questions for the SG 1.Should we decide which layer (or, what address) the forwarding algorithm should be based? 2.Should we decide one forwarding algorithm? 3.Can we only define the communication message format rather than the algorithm? 4.Can we only define the MAC interface so the same hardware module can be shared? 5.How much interoperability among vendors required?