1. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 1/13 Simple Routing Method application to P1394.1 Philippe Boucachard Email: boucachard@std.canon.co.jp Laurent Frouin Email: frouin@crf.canon.fr

2. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 2/13 Configuration is a heavy process - bus number allocation algorithm - address assignment Background: - Bit mapped routing - Management of routing table is a heavy task - when breaking a bus, - or joining buses. Large protocol overhead Network idleness when handling routing management No provision for network congestion management (proposal currently being drafted) Remaining issues

3. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 3/13 Seems to be rejected because: - ARP-like facility is needed - Memory consuming solution - Joining buses still is a big issue Based on - Virtual bus number - Distributed bus number (path address) assignment - Persistent assignment - No need to coordinate bus number between portals This was introduced at last December meeting (proposed by David Wooten) Background: - Path Dependent addressing -

4. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 4/13 Rather in-line with path dependent addressing solution - Solving memory consumption problem - Reducing complexity - Easily joining bus Proposal objective - Simple Routing Method - In addition it addresses - congestion avoidance - relates to virtual Id mechanism Even if it still needs an ARP-like mechanism, this is a requirement unavoidable in any flexible network where addresses are not statically assigned...

5. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 5/13 Principle of Simple Routing Method A0A0 A1A1 A0A0 B0B0 B1B1 K0K0 K1K1 L0L0 L1L1 B0B0 A1A1 A1A1 K1K1 L0L0 3FF 16 L1L1 offset_ A 0 offset_ L 1 L0L0 S D Source bridge Destination bridge Intermediate bridge Uses fields previously meant as BusID as source routing header Offset points to a path descriptor in bridge memory.

6. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 6/13 3 bridges per bus9 bridge hopsmax 62 Buses Limitations of the Simple Routing Method 7 bridges per bus5 bridge hopsmax 86 Buses Mixed7 bridge hopsmax 58 Buses one 7-bridge bus six 3-bridge bus Bus number limitation: GASP needs to include a path description field. ARP-like mechanism still needed (to be developed).

7. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 7/13 - Configuration bus numbering routing table initialisation - Packet routing remote asynchronous transfer routing decision - Maintenance joining buses splitting buses Simple Routing Method provides a solution to every main problems attached to asynchronous packet routing

8. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 8/13 Configuration - Routing labelling - Self-numbering of routing label - based on alpha-portal mechanism - routing label mapping is added for portal only - persistent across bus reset Routing label bit wise configuration - 2, 3, 4, 5-bit routing label width has to be selected - it fixes maximum number of portal per bridge (3, 7, 15, 31, … ) Routing cache table(can be less than 1024 bits) - to be initialised through ARP and response packet Physical IDVirtual IDEUI-64Routing label 4 p 0@  0 21@  - 0 p 3@  2 12@  - ……...

9. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 9/13 Packet routing- Source bridge - 1- Eavesdrop primary packet on local bus 2- Check next routing info (all “ 1 ” for local packet) 3- Check source bus ID = “ 3ff 16 ”, then source bridge processing 4- Get offset value from primary packet 5- From routing cache table, get corresponding path description from offset 6- Fill-up routing header (Go-path, Back routing label, Phy->Virtual conversion) 7- Forward packet 110 2 011 2 001 2 3FF 16 1F 16 00 2 2 3 4 5 011 2 - - - - - - - 6 110 2 001 2 11111 2 001111 2 16 x 64 1F 16

10. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 10/13 Packet routing- Intermediate bridge - 1- Eavesdrop primary packet on local bus 2- Check next routing info (all “ 1 ” for local packet) 3- Neither source nor destination case, then intermediate bridge processing 4- Strip “ go-path ” routing info, rotating bus ID fields 5- Fill-up “ back-path ” routing info 6- Forward packet 011 2 000 2 00 2 - - 5 001 2 000 2 1111 2 001 2 00 2 - - 11111 2 2 00 2 1212 001 2 011 2 4 5 4 3

11. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 11/13 Packet routing- Destination bridge - 1- Eavesdrop primary packet on local bus 2- Check next routing info (all “ 1 ” for local packet) 3- Check separator location close to end, then destination bridge processing 4- Get back-path value from primary packet 5- From routing cache table, get offset attached to corresponding path value 6- Fill-up routing header (offset, dest bus ID = 3FF, Virtual->Phy conversion) 7- Forward packet 000 2 001 2 11 2 2 3 5 001 2 - - - - - 6 000 2 011 2 11111 2 101111 2 16 x 64 0A 16 011 2 3FF 16 0A 16 10 2 11 2 4

12. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 12/13 Maintenance- Joining buses - Local processing only: - select the new alpha portal (to be synchronised with alpha portal mechanism behaviour) - start quarantine period for victim bridge (quarantine period duration may depends on routing cache table maintenance, for instance...) - new routing label attribution for victim bridge(s) Main advantages: - local processing only! - any path that is not going through victim bus still is valid - only few things need to be standardised (most is implementation dependent)

13. P1394.1/BR050R00March 25th, 1999 Simple Routing Method 13/13 Conclusions To limit bridge number per bus could be a good way to deal with congestion avoidance. More than 50 buses is probably not so useful, anyway … …it is probably not so critical not being able to reach any node while you can efficiently communicate with who you need to! Node Id virtualisation is extended up to Bus ID that is globally persistent across bus reset (coherent routing scheme) This proposal is in-line with P1394.1 Draft 0.04, Feb’99 and could participate to light but efficient standard, making possible some low cost implementation The number of portals could be easily extended beyond 2, without breaking the routing scheme. Some open issues: ARP-like facility, extension of Simple Routing Method coverage ….