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Setting Up Routing Vectors in a Network of Bridged 1394 buses

Setting Up Routing Vectors in a Network of Bridged 1394 buses. Subrata Banerjee PHILIPS Research Briarcliff, New York. P1394.1 WG Meeting, Milpitas, California April 26-27, 1999. PHILIPS Research. Problem Statement.

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Setting Up Routing Vectors in a Network of Bridged 1394 buses

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  1. Setting Up Routing Vectors in a Network of Bridged 1394 buses Subrata Banerjee PHILIPS Research Briarcliff, New York P1394.1 WG Meeting, Milpitas, CaliforniaApril 26-27, 1999 PHILIPS Research

  2. Problem Statement • While progress has been made in the format and syntax of routing tables, so far no discussion took place on computing and setting up the routing table entries • Current SCAT item • Linked with bus id assignment, prime portal selection, joining/breaking nets, etc. • Goal is to make us start thinking on this topic. PHILIPS

  3. Can the Internet Approach be Applied Here? • Summary: • Determine network topology via neighbor discovery and local topology broadcast • Have a flooding based broadcast mechanism!Why? • Works even during initialization/boot-up phase when no routing information is available • Well-known to be the most reliable routing approach • So, how does it work? PHILIPS

  4. Broadcasting via Flooding • Each node repeats incoming information toall its outgoing linksexcept the link on whichit was received • Lot of redundant messages! Yes.Makes it robust and work in unknown topologies • No. of redundant messages is limited via sequence numbering and hop-counts (details …) 0 Bridge 3 1 Network 2 4 5 Bus PHILIPS

  5. How can flooding work in 1394 Network? • First each bus selects its bus representative portal (BRP) [ f (GUIDs), etc.] • All “flooded” messages are handled by the BRPs • GUID of the BRP = Temporary id. of the bus • Now BRPs can employ flooding to exchange information • Implementation can be optimized for speed/cost • Used only for certain type of broadcast messages PHILIPS

  6. Now what? Finding trees and picturing the forest • Each BRP determines the ids. of its neighboring BRPs • Broadcasts this local topology information via flooding • Upon receiving these messages each BRP determines the “forest from the trees” • Now each BRP has a complete knowledge of the network topology. PHILIPS

  7. OK. What then? Compute Routes ... • Centralized approach • Elect NRP (Net Representative Portal, or Prime Portal)f (BRP Ids.) • NRP computes routes (based on some “least cost” algorithm) • NRP broadcasts the routing information in the net • BRPs, based on this information sets up the routing tables in all portals in its bus PHILIPS

  8. Compute Routes • Distributed approach • Each BRP has the same topology information • Based on that, each BRP independently executes the same route computation algorithm • Each BRP, based on its route computations sets up the routing tables in all portals in its bus PHILIPS

  9. Update Routes • If there is a “significant” change in routing related information (such as available bridge/bus capacity, broken link, etc.) thenthe relevant bridge portal sends a broadcast message to the network. • Upon receiving this message all routing tables are updated after a selective route computation in a centralized or distributed manner. • Periodic updates from BRPs as heartbeats PHILIPS

  10. Joining two nets • BRPs at the meeting point of two 1394 nets exchange topology information • Relatively straightforward details ... PHILIPS

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