This object indicates the cause that the session becomes Down. Options: 1. sessionUp(0) -indicates that the session was Up. 2. helloHoldTimerExp(1) -indicates that the Hello hold timer expired. 3. ssnHoldTimerExp(2) -indicates that the session hold timer expired. 4. resetMplsLdp(3) -indicates MPLS LDP was reset. 5. undoMplsLdp(4) -indicates that MPLS LDP was disabled. 6. undoMpls(5) -indicates that MPLS was disabled. 7. undoMplsLdpRemotePeer(6) -indicates that the remote peer was deleted. 8. modifyGRConfig(7) -indicates that GR capability was modified. 9. modifyGRTimer(8) -indicates that the GR timer was modified. 10. modifyKeepaliveTimer(9) -indicates that the keepalive timer was modified. 11. modifyMD5Config(10) -indicates that MD5 was configured. 12. ssnRoleSwitch(11) -indicates that the session role was switched. 13. modifyMTUConfig(12) -indicates that the MTU was modified. 14. modifyTransportAddress(13) -indicates that the transport address was modified. 15. modifyLDPLsrID(14) -indicates that the LDP LSR ID was modified. 16. recvNotification(15) -indicates that the notification message was received. 17. transportAddressNotMatch(16) -indicates that the transport address was not matched. 18. protocolGR(17) -indicates that the protocol GR was in processing. 19. ifStatusChanged(18) -indicates that the interface status was changed. 20. tcpDown(19) -indicates that TCP was Down. 21. otherReason(20) -indicates that another cause was involved. 22. sentNotification(21) -indicates that the notification was sent. 23. canntBuildSessionRelation(22) -indicates that the session relation cannot be built. 24. receiveErrorMessageFromPeer(23) -indicates that error message from peer was received. 25. receiveSocketError(24) -indicates that error pakcet from socket was received. 26. sessionDelete(25) -indicates that the session was deleted. 27. modifyCapabilityAnnouncementConfig(26) -indicates that the capability-announcement was modified. 28. modifyLocalLsrID(27) -indicates that the Local LSR ID was modified. 29. modifyP2MP(28) -indicates that the mLDP P2MP was modified. 30. modifyMP2MP(29) -indicates that the mLDP MP2MP was modified.