Implement Sequence Number Rollover Patch in HSVF D6

Pursuant to Advisory Notice A22-005, The MX would like to announce the implementation of a patch to HSVF D6 to permit the rollover of Sequence numbers automatically once the protocol version maximum capacity of 999,999,999 is breached.

This will only impact clients who have not yet made the transition to HSVF D7.

1. Implementation date is February 23rd 2023.
2. HSVF D5 will be decommissioned on February 23rd 2023 and will not receive the patch
3. The Rollover will be preceded by a Bulletin (L Message)
   • "MAX SEQUENCE NUMBER 999,999,999 REACHED, PREPARE ROLLBACK TO 0"
     • Bulletin sent with message 999,999,999
     • Sequence number 0 follows 999,999,999 (which represents 1,000,000,000).

Retransmissions following a Sequence Number Rollover

• The last 999,999,999 messages sent in HSVF are available for retransmissions, following a Rollover.
• Example:
  • HSVF D6 Options Level 2
  • Last Sequence Number following a Rollover = 200,000,000
    • Represents message 1,200,000,000
    • Messages available for retransmission
      • 200,000,001 (pre Rollover) to 200,000,000 (post Rollover)
  • A request for actual messages 999,999,998 to 1,000,000,001
    • Request = Start=999,999,998, End=1
    • Return = 999,999,998; 999,999,999; 0; 1

Timeline