NAME

  T2ShutdownRetrans1.seq - SHUTDOWN message is transmitted again if T2-shutdown timer expires


PURPOSE

  To check that if T1-shutdown timer expires then the endpoint MUST retransmit
  SHUTDOWN and restart the T1-shutdown timer.


SYNOPSIS

  ./T2ShutdownRetrans1.seq [-tooloption ...] -pkt ./T2ShutdownRetrans1.def
    -tooloption : v6eval tool option
  See Also: ../common/STD_PKT_COMMON.def
            ../common/SCTP_COMMON.def


PRE-TEST CONDITION

  Association is established between endpoint A and B. Arrange the
  data in endpoint A such that no SHUTDOWN-ACK is sent in response
  to SHUTDOWN.


TEST PROCEDURE

  Endpoint A                           Endpoint B                ULP
  (ESTABLISHED)                        (ESTABLISHED)
                                                   <-----    Terminate
                <----------------       SHUTDOWN
                                           |
                                           | T2-Shutdown
                                           | Timer
                                           |
                <----------------       SHUTDOWN
  TEST DESCRIPTION:
  1. Try to terminate an association between endpoint A and endpoint B by
     sending SHUTDOWN message from endpoint B. Don't send the SHUTDOWN-ACK
     or any DATAGRAM from the endpoint A.
  2. Check A: After expiry of T2-Shutdown timer, SHUTDOWN message is sent
     again.


NOTE

  None


REFERENCE

  RFC 4960
  9.2.  Shutdown of an Association
    Once all its outstanding data has been acknowledged, the endpoint
    shall send a SHUTDOWN chunk to its peer including in the Cumulative
    TSN Ack field the last sequential TSN it has received from the peer.
    It shall then start the T2-shutdown timer and enter the SHUTDOWN-SENT
    state.  If the timer expires, the endpoint must resend the SHUTDOWN
    with the updated last sequential TSN received from its peer.
    The rules in Section 6.3 MUST be followed to determine the proper
    timer value for T2-shutdown.  To indicate any gaps in TSN, the
    endpoint may also bundle a SACK with the SHUTDOWN chunk in the same
    SCTP packet.
    An endpoint should limit the number of retransmissions of the
    SHUTDOWN chunk to the protocol parameter 'Association.Max.Retrans'.
    If this threshold is exceeded, the endpoint should destroy the TCB
    and MUST report the peer endpoint unreachable to the upper layer (and
    thus the association enters the CLOSED state).  The reception of any
    packet from its peer (i.e., as the peer sends all of its queued DATA
    chunks) should clear the endpoint's retransmission count and restart
    the T2-shutdown timer, giving its peer ample opportunity to transmit
    all of its queued DATA chunks that have not yet been sent.