Method for detecting invalid packets by rewriting transaction identifers

DETAILED DESCRIPTION The present invention provides a method for reliable stale packet recognition in a network.
The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements.
Various modifications to the preferred embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments.
Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.
The method in accordance with the present invention provides reliable stale packet recognition in a network utilizing LonTalk by blocking duplicate packets which arrive at the receiving router after the expiration of the transaction timer.
When a packet for a new transaction to be sent to the receiving node is assigned the same transaction identifier (TID) as a packet of the previous transaction, the sending router rewrites the packet's TID to avoid the erroneous recognition of this packet as a stale duplicate by the receiving router.
In this manner, the packet for the new transaction will not be mistakenly blocked as a stale duplicate packet by the receiving router.
To more particularly describe the features of the present invention, please refer to FIGS.
2 through 5 in conjunction with the discussion below.
FIG.
2 is a flow chart illustrating a preferred embodiment of a method for reliable stale packet recognition in accordance with the present invention.
Steps 202-206 are performed by the sending router 108, while steps 208-212 are performed by the receiving router 114.
First, the sending router 108 (FIG.
1) determines if a packet 106 could be erroneously seen as a stale duplicate packet by the receiving router 114, via step 202.
If so, then the packet's TID is rewritten, via step 204, such that the error is avoided.
The packet could be erroneously seen as a duplicate packet by the receiving router 114 if the packet 106 is part of a new transaction but is assigned a TID which is identical to a TID assigned to a packet of the previous transaction