From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: den 2 juni 2014 09:20 To: Hans Feldt Cc: opensaf-devel@lists.sourceforge.net Subject: Re: [opensaf:tickets] #654 MDS improvements
Hi Hans, On 5/20/2014 12:36 AM, Hans Feldt wrote: Next steps: - Set DEST_DROPPABLE=False What are we planning to achieve ? if it is only for Loging , we already have `i_msg_loss_indication` flag which is part of svc_install , if enabled any message is lost a callback of type MDS_CALLBACK_MSG_LOSS is delivered to application. [Hans] DEST_DROPPABLE works on the sending node whereas MDS_CALLBACK_MSG_LOSS works on the receiving node. So I guess they can just complement each other? We can never have too much info... IMMA already enabled this. - Explore TIPC Multicast for MDS broadcast This will be addressed in #851 ( http://sourceforge.net/p/opensaf/tickets/851) [Hans] OK let's use this ticket to be explicit about the change. I did a quick HACK and got it to work! The question is how can it be done properly? -AVM ________________________________ [tickets:#654]<http://sourceforge.net/p/opensaf/tickets/654/> MDS improvements Status: accepted Milestone: 4.5.FC Created: Wed Dec 11, 2013 10:26 AM UTC by Hans Feldt Last Updated: Mon May 19, 2014 07:04 PM UTC Owner: Hans Feldt Identified short comings: * MDS does not use the segmentation/reassembly support in the underlying transport protocol. For example TIPC accepts messages upto 66000 bytes * The built in segmentation/reassembly is totally insecure, lost fragments are not retransmitted and the complete message is dropped (without users knowledge) * In TIPC mode DEST_DROPPABLE is not used at all. This means that messages can be silently dropped at a receiving node at congestion. Suggested improvements: 1) Introduce a variable fragmentation limit when sending messages. This needs to be based on information received at service discovery. If the sender is "old" use the classic 1400 byte limit. If the sender is new, first use TIPCs segmentation/reassembly and then the MDS one. 2) Configure DEST_DROPPABLE=False and use returned messages for diagnostics (as a first step). That means only for logging purposes and not for retransmission (which is not possible since messages are not stored in a send queue) I have working prototype patches for both. Will send out them shortly. Using TIPC segmentation/reassembly gives a number of advantages: - reduced risk of link congestion on sending node since TIPC counts messages not bytes - secure transport of large messages, TIPC handles retransmission - possibly improved characteristics due to implicit use of Ethernet jumbo frames Long term we should consider if MDS segmentation/reassembly can be removed. Sending large messages should really be using stream sockets. ________________________________ Sent from sourceforge.net because you indicated interest in https://sourceforge.net/p/opensaf/tickets/654/ To unsubscribe from further messages, please visit https://sourceforge.net/auth/subscriptions/ ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. Written by three acclaimed leaders in the field, this first edition is now available. Download your free book today! http://p.sf.net/sfu/NeoTech _______________________________________________ Opensaf-devel mailing list Opensaf-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/opensaf-devel
