FCO DEBET-F003 Rev B, HELLO messages w/SNAP header

This Field Change Order (FCO DEBET-F003 Rev B) addresses a range of software and firmware issues in DEBET LAN BRIDGE 150 models (including specific variants like DEBET-AC, DEBET-AD, etc.) at or below Revision Level "D01". The primary problem identified is the incorrect processing of HELLO messages containing a SNAP header, which were being treated as regular HELLO messages.

Beyond this, the FCO corrects numerous other symptoms, such as incorrect responses to all-bridge-multicast addresses, faulty address filtering after reboot, inaccuracies in the "second operating" counter, issues with no-frame-interval logic and LANCE testing, improper packet forwarding in IEEE backup mode, power-up counter errors with "INIT WITH DEFAULTS" commands, and failure to forward oversized packets.

The solution involves replacing the microcode ROMs at locations E131 and E132 with updated versions (23-655E6-00 and 23-654E6-00, respectively) provided in the FCO EQ Kit (EQ-01646-01). The rework procedure, estimated to take one hour, includes detailed steps for power removal, chassis disassembly, ROM replacement with ESD precautions, and applying new revision stickers ("E" and "1") to the unit.

Verification after installation requires checking the unit tag for a Revision level of "E1" or above, and confirming that the software version is V1.4 or higher using the Extended LAN Management Software (ELMS). Testing involves diagnostic self-tests upon power-up and verifying logical link communication between network nodes.