No subject

LSACK the prematurely aged entries before starting to send fresh
LSUPDs with InitialSequenceNumber 0x80000001 (and not ...00).

Casual grep suggests that other places where the sequence number is
incremented, there isn't any warp-around check either.

Lab setup:

- 2x JunOS 9.3
- 1x BIRD OSPF (1.2.2) on Linux
- 1x Quagga OSPF (0.98.x, 0.99.16) on Linux

All connected on a single Ethernet as Area 0. The JunOS systems are
DR/BDR.

For the curious, the inter-op aftermath is this:

- Quagga's ospfd, on receiving the bad LSUPD, correctly logs the
  abnormality and then segfaults instantly [bug #586]
- JunOS just doesn't care and installs the entry with the illegal
  sequence number and sends it to other routers as usual -- thereby
  making a restart of quagga's ospfd very very short-lived and sad
- The situation only resolves itself after one hour (the illegal LSUPD
  reaches MaxAge) or by forcefully purging the entry from the other
  systems' databases

Regards,
- D.