| Event Id | 631 |
| Source | SNA Server (or SNA Application) |
| Description | Invalid message received across the LAN: remote: (IP address):1477 Bad sequence number 183 (expected 184) |
| Event Information | According to Microsoft: Cause: If SNA Server data is being sent and received simultaneously over a single client-server LAN connection (to or from one client), internal "send sequence number" and "receive sequence number" variables may be incremented from different threads at the same instant. If this timing condition occurs on a DEC Alpha computer, one sequence number may fail to be updated, causing SNA Server to incorrectly detect an out-of-sequence message. These sequence number variables occur on consecutive BYTE boundaries within a non-packed structure. The DEC Alpha appears to improperly lock one of the BYTE values during a increment operation on an adjoining, separate BYTE value, preventing it from being updated. Resolution: To resolve this problem, obtain the latest service pack for SNA Server version 4.0. |
| Reference Links | SNA Server Drops Client LAN Connection, Logs Event 631 on DEC Alpha |
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