NANC 351

Recovery Enhancements – “Send What I Missed” recovery message

Origination Date :04/12/2002



Business Need:

The NPAC SMS and Service Provider SOA/LSMS exchange messages and a response is required for each message.  The current NPAC architecture requires a response to every message within a 15-minute window, or the requestor will abort the association.

If a Service Provider fails to respond to an NPAC message, the NPAC aborts that specific association and the Service Provider must re-associate in recovery mode, request a “best guess” time range of missed messages from the NPAC, receive and process all missed messages, then start processing in normal mode until they are totally caught up with the backlog of messages.

One problem of the current “best guess” approach is the trial-and-error recovery processing that a Service Provider must perform in certain circumstances (e.g., when there is too much data to send in a response to a single request).  This can create unnecessary workload on both the NPAC and the Service Provider.

A better method is to implement the “Send What I Missed” approach (SWIM).  Service Providers can optionally use this new message to perform the recovery function.  This improves the efficiency of recovery processing for the NPAC and Service Providers because guesswork is eliminated.

Final Resolution:

Interface and Functional Backwards Compatible:  YES

Create a new process that incorporates the ability for a Service Provider to request that the NPAC send missed messages.  In order to accomplish this, the NPAC will need to keep track of messages that were both “not sent ” and “not responded to ” from the NPAC to the SOA/LSMS.

The behavior of the “Send What I Missed” message (SWIM) which will be initiated by a SOA/LSMS, is the same as the current recovery process (i.e., request from the SP, response from the NPAC includes the recoverable data).  The implementation would use the existing recovery message, and incorporate a new attribute (SWIM, to go along with time range and TN range).  When this is received, the NPAC would send back a SWIM Response which contains the missed messages.  With the new SWIM attribute, the NPAC would use the same Blocking Factor tunables as used in 187-Linked Replies in order to send data to the SOA/LSMS in “chunks”.

Implemented in FRS 3.3.0a, IIS 3.3.0a, GDMO 3.3.0 and ASN.1 3.3.0.

Related Release:

Implemented in FRS 3.3.0a, IIS 3.3.0a, GDMO 3.3.0 and ASN.1 3.3.0.

Status: Implemented