prom L2 Address Change Entry

1.3.6.1.4.1.2167.5.1.4.4.4.1

The address change table provides a quick way of getting only the entries that have recently changed. Since entries age out as part of the normal switching process, entries that have aged (i.e. their destination bindings are no longer valid) are not considered to be changed. Any other modification to the entry, including deletion or creation, are considered to be changes. The address change table is considered a circular table. When an entry changes, it is added to the next position within the table. If the 'next' position goes beyond the end of the table, the 'next' position is set to the beginning of the table (1) and the wrap counter (promAddressChangeWraps) is incremented. The promAddressChangeLast value is updated with the index of the last entered entry. An entry may be in the table multiple times if it has changed multiple times. Every time that an entry changes, it is added to the change table. A network management application should follow the following algorithm when polling this table: 1. Set lastChangeWrap = promAddressChangeWraps. 2. Set lastChangeIndex = promAddressChangeLast 3. Get the entire promAddressEntryTable. 4. Submit a getNext for ., updating lastChangeWrap and lastChangeIndex with the returned next values. Update the address entry database with the changed values. 5. Repeat step 4 until no more entries are returned. 6. Wait polling timeout period. 7. Get wrap events counter and last index. If the wrap events counter is equal to lastChangeWrap, then goto step 4. Else if the wrap events counter is more then one greater then lastChangeWrap, goto step 1. Else the wrap events counter is exactly one greater then lastChangeWrap, and if the last index is greater then lastChangeIndex, then goto step 1, else goto step 4. The last step simply insures that we have not missed any of the change entries. Essentially it says that if we have wrapped to beyond where we last polled, then we must get the entire table to synch up again. Otherwise we can just get the entries that have changed.