T3ExpiresRTOInc.seq - RTO is updated correctly if T3-rxt timer expires for a DATA message
To check that if T3-rxt expires on a destination address then the
value of RTO is updated correctly for that address.
./T3ExpiresRTOInc.seq [-tooloption ...] -pkt ./T3ExpiresRTOInc.def
-tooloption : v6eval tool option
See Also: ../common/STD_PKT_COMMON.def
../common/SCTP_COMMON.def
Association is established between endpoint A and B. Arrange the data
in endpoint A such that SACK is not sent for the data received from
endpoint B.
Endpoint A Endpoint B ULP
(ESTABLISHED) (ESTABLISHED)
<----- Send
<---------------- DATA
(Start T3-rtx timer)
|
| T3-rtx timer expired
|
<---------------- DATA
|
| T3-rtx timer expired
|
<---------------- DATA
.
. Retransmit x
. times
TEST DESCRIPTION:
1. Attempt to send DATA from endpoint B to A. Don't send SACK from A.
Let the timer T3-rxt expire. DATA will be retransmitted. Note the
timer. Don't send SACK for the retransmitted DATA. T3-rxt will be
expired again and again DATA will be retransmitted.
Record the messages using a signal emulator.
2. Check A: Value of the T3-rxt is updated correctly.
1. If configure of ASSOC_MAX_RETRANS is not lager enough, test will exit
even if RTO is not up to RTO_MAX.
2. If the retransmit time is 0.5s less or greater than RTO, do accept it
because we can not exactly calculate it.
RFC 4960
6.3.3. Handle T3-rtx Expiration
Whenever the retransmission timer T3-rtx expires for a destination
address, do the following:
E1) For the destination address for which the timer expires, adjust
its ssthresh with rules defined in Section 7.2.3 and set the
cwnd <- MTU.
E2) For the destination address for which the timer expires, set RTO
<- RTO * 2 ("back off the timer"). The maximum value discussed
in rule C7 above (RTO.max) may be used to provide an upper bound
to this doubling operation.
E3) Determine how many of the earliest (i.e., lowest TSN)
outstanding DATA chunks for the address for which the T3-rtx has
expired will fit into a single packet, subject to the MTU
constraint for the path corresponding to the destination
transport address to which the retransmission is being sent
(this may be different from the address for which the timer
expires; see Section 6.4). Call this value K. Bundle and
retransmit those K DATA chunks in a single packet to the
destination endpoint.
E4) Start the retransmission timer T3-rtx on the destination address
to which the retransmission is sent, if rule R1 above indicates
to do so. The RTO to be used for starting T3-rtx should be the
one for the destination address to which the retransmission is
sent, which, when the receiver is multi-homed, may be different
from the destination address for which the timer expired (see
Section 6.4 below).