Hi Sagi, On Sun, 2007-06-10 at 11:59, Sagi Schlanger wrote: > Hi, > > I'm looking for some answers on Up-Down routing at OpenSM . > > Is anybody familiar with a utility/procedure to find credit loops > given a topology and routing settings?
I know there was at least talk of ibdiagnet (in ibutils) checking this. Not sure if it is implemented (yet) or if it is routing algorithm independent. Eitan ? > Is there a handy spec describing the OpenSM Up-Down algorithm? The OpenSM up/down routing is based on the following paper: "Effective Strategy to Compute Forwarding Tables for InfiniBand Networks" Jose Carlos Sancho, Universidad Politécnica de Valencia Antonio Robles, Universidad Politécnica de Valencia Jose Duato, Universidad Politécnica de Valencia http://csdl2.computer.org/persagen/DLAbsToc.jsp?resourcePath=/dl/proceedings/&toc=comp/proceedings/icpp/2001/1257/00/1257toc.xml&DOI=10.1109/ICPP.2001.952046 > What is the scheme through which roots are defined on clos and non > clos/fat tree topologies? The admin can supply the roots via -a <guid_list_file> option when invoking OpenSM. Auto-detect root nodes - based on the CA hop length from any switch in the subnet, a statistical histogram is built for each switch (hop num vs number of occurrences). If the histogram reflects a specific column (higher than others) for a certain node, then it is marked as a root node. Since the algorithm is statistical, it may not find any root nodes. The list of the root nodes found by this auto-detect stage is used by the ranking process stage. Note 1: The user can override the node list manually. Note 2: If this stage cannot find any root nodes, and the user did not specify a guid list file, OpenSM defaults back to the Min Hop routing algorithm. > Is this algorithm always credit loop free? It's supposed to be. > How efficient is using this algorithm on non clos/fat tree topologies? What do you mean by efficiency ? Also, are you asking about pure fat tree or non pure fat tree (or both) ? -- Hal > Thanks for your cooperation, > Sagi > > ____________________________________________________________ > Sagi Schlanger | +972-9-9717651 (o) | +972-52-2385154 (m) > Software Engineer, IB Switch > Voltaire – The Grid Backbone > > www.voltaire.com > > > > ______________________________________________________________________ > > _______________________________________________ > general mailing list > [email protected] > http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general > > To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general _______________________________________________ general mailing list [email protected] http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
